Powering the Fuji X-T3


This comprehensive reference guide assembles information relevant to supplying power to the Fujifilm X-T3 camera, in an optimal way. The level of examination ranges from broad system overviews, to detailed analysis suitable for persons who are using the X-T3 professionally. Although this information is presented within the context of the X-T3 camera, much of it (particularly the information regarding NP-W126 type batteries) is also relevant to other Fuji X-series cameras. I hope that this can help you to get the most out of your Fujifilm camera. There is an important disclaimer at the end of this guide. Please read it before acting upon any information given here.



Body only power configuration options
Body and grip power configuration options


Distinguishing between S and non-S
Performance differences
Determining the production date


Genuine vs non-OEM batteries
Discharge characteristics
Identifying counterfeit batteries


Battery discharge sequence
Battery deployment strategies
9 Volt DC input options


State of health
State of charge
Calendar fade
Cycle fade
Detriments to service life
Charge rates
Charging times
Voltage limits for charge and discharge
Temperature limits
Voltage stabilisation
Measuring battery voltage
Battery contacts
Determining the battery’s end of life
Li-ion fire hazard


View Mode setting
Auto Power Off setting
Power management menu
Boost mode
Performance mode differences


BC-W126S / BC-W126
Non-OEM chargers
Over-temperature protection


Connection mode
Connector types
Internal charging
External powering
USB power sources
Fujifilm AC-5VF power adapter


Removable battery power banks
Expected efficiency
Multi-voltage power banks
Power banks recommended by Fujifilm


9 Volt supply options
Applications & examples

K – Alternative Power Supplies

Automotive power
How to use solar power

L – USB Power Meters

M – Disclaimer




Currently (late 2018), the X-T3 camera boasts the most sophisticated and versatile power management system of any X-series camera to date.  Many of its power management improvements were introduced with the X-T2 model. The significant differences between the X-T3’s power system, and the very similar power systems of the X-T2 and X-H1, are the X-T3’s adoption of the USB-C standard for USB connection, and the ability to achieve maximum performance without having to use the optional battery grip.

The electrical specifications of the X-T3, are found on the identification and compliance plates. The one belonging to the camera body, is at the back of the tilt LCD screen, and can be seen when the screen’s top is pulled outward, while the other plate is found on the top surface of the optional vertical grip. Both state that the camera is rated at 9 Volts up to a power of 18 Watts.

In terms of power options, use of the grip adds some, but at the same time, obstructs some others. For instance, while the grip is attached, there is no access to the camera body’s battery chamber. Because of this, there are two slightly different power configuration schemes for the X-T3, depending on whether or not the optional vertical grip is used.

When the optional VG-XT3 grip is used, it is possible to leave the grip attached quasi-permanently, since there is no need to access the body battery for external charging, (although, you still have the external charging option, if desired).

Section – B


The NP-W126S is the specified battery for the X-T3 system (X-T3 body and optional VG-XT3 grip). Because some X-T3 owners might already have NP-W126 (non-S) batteries from an earlier camera, and they would like to use those batteries in the X-T3, the distinction between the two battery types can become an issue. The newer NP-W126S battery is a higher performance version of the NP-W126 battery, and was introduced to meet the needs of the X-T2 camera. These requirements on battery capability are extended further by the X-T3’s even higher performance specification. To the question “Can NP-W126 (non-S) batteries be used in the X-T3?”, the short answer is “Yes, but the camera may not be able to perform at its highest specification potential”. For some types of photography (for instance, Landscape photography, and Product photography) a reduction in “speed” performance, may simply not be an issue.

The NP-W126 and NP-W126S batteries are identical in terms of physical dimensions and power capacity, and may be considered interchangeable for lower paced situations where top performance is not required.

The specific internal difference between the two battery types is the lower internal resistance characteristics of the “S” version.  Low resistance enables high current flow with minimal temperature rise.  The readily identifiable visual indicator of battery type is the orange square on the end of regular NP-W126 batteries, and the orange circle (plus the orange insertion direction arrow) on the NP-W126S batteries.

When the X-T3 is powered up, any battery that is not an NP-W126S (this includes the NP-W126, and non-OEM batteries), is identified. The X-T3 determines the type by measuring for high resistance (about 680kΩ or higher) on the [S] contact of the battery, to indicate an “S” type battery. (If you tape over the [S] contact of a non-S type battery, effectively giving it infinite resistance, the X-T3 will mistakenly recognise that battery as an NP-W126S battery). If three batteries are loaded (1 in the body, 2 in the grip), at power up, the battery symbols for the grip batteries, display briefly with the “three dots” (meaning the battery’s state of charge is being assessed). At this stage, the “S” or “non-S” battery type has already been determined, and Left and Right grip battery indicators show in either white (for “S” type) or yellow (for “non-S” type battery).

Within one second, the display shows all three battery indicators, with their appropriate charge levels, and displayed in either white or yellow. Any yellow display (meaning a “non-S” battery is detected), will be accompanied by a message recommending the use of NP-W126S batteries.

Note that the message uses the advisory “Please use …” rather than the imperative “You must use …”. This, as well as the fact that the camera continues to work, indicates that the message is to be taken as an recommendation, rather than a directive. Note that the battery’s [S] and [T] terminals (in between the positive and negative terminals), are not involved in the determination of the battery’s “S” or “non-S” type, since the camera is able to correctly identify the type, even if these two middle battery contacts are taped over.

The performance differences between the regular and the type-S battery, are to do with sustained high power delivery over time, rather than with stored capacity.  The type-S battery was intended to meet the increased endurance requirements of the previous X-T2 camera, when operating in scenarios such as high-rate continuous stills shooting, and long duration 4K video capture. Without the higher performance battery type, sustained high power usage could produce elevated battery temperature, an increase of the battery’s internal resistance, and a drop in output voltage, leading to possible camera “lock-up” events. In a lock-up event, the camera becomes unresponsive to all controls, including the on/off switch. Typically, the batteries must be removed and re-inserted before operation can be restored. The NP-W126S battery’s lower internal resistance characteristics were designed to address such issues.  At the time of introduction (for the X-T2) Fujifilm stated that the improved battery could deliver three times longer duration of continuous shooting, even under 40 ℃ environmental conditions.  However, for less demanding usage scenarios, the regular NP-W126 battery should perform satisfactorily, although with limitations to the X-T3’s boost mode.

The battery’s performance potential declines over time, even if not being used. Therefore, in order to assess their service viability, it is useful to be able to determine the age of the NP-W126 class batteries, via their production date. This is recorded via an impressed alpha-numeric code on the end of the battery opposite to the electrical contacts end.

NP-W126 batteries having codes beginning with T, S, R, and P, had 5 characters. For codes beginning with N, and then on all NP-W126S batteries, the code is extended to 8 characters. (Please note that very early versions of the battery, prior to having the orange orientation patch, used a different production code system to the one described here). Of the 8 characters, the first three are the date code, the middle two  (usually “1A” or “2A”), are undisclosed production information, and the last three are a manufacturing plant code. Note that Day of Month codes, don’t use alphabetic upper-case “I”, to avoid confusion with numeric character “1”, one. (However, this is not an issue for Year and Month codes, which don’t use numbers at all). For similar reasons, zero, “O” and “Q”, are not used. To the camera user, it is the first two characters (indicating year and month) that are of interest.

The production date information can be decoded by using the chart below. In the above illustration, the “KGT” date code can be decoded as “2018, July, 26”.  Note that the year of production code proceeds in a reverse order. As a consequence, a letter closer to the beginning of the alphabet represent more recently produced battery. Since a Li-Ion battery’s prime operating condition only lasts about two years it is worthwhile remembering the year codes representing the last two years, since these represent the batteries that are currently within their prime. Batteries beyond the two year period may still be usable for casual photography, but for critical and high power demand usage,  batteries within the recent two year production period, should be preferred.

At time of release, the X-T3 should have been supplied with a battery whose production code starts with K. As we get a few months into 2019, production codes starting with J should start showing up.



Non-OEM (Original Equipment Manufacturer) batteries are also known as third-party batteries. Batteries that are “nominally” equivalent to the NP-W126, but not genuine Fujifilm batteries, (and therefore, not manufactured by Panasonic Energy Wuxi), are readily available, and at prices significantly below the price of the genuine NP-W126S batteries. Although the nominal specifications may suggest the non-OEM battery as a viable alternative to the genuine battery, there can be significant performance, behavioural, and safety differences.

Although more costly in the short term, genuine Fujifilm batteries offer the following advantages over non-OEM batteries:

Stated capacity is reliable. The genuine Fujifilm batteries are rated at a capacity at or close to the maximum that is attainable for the technology, and their nominal capacity matches their actual capacity. Third-party batteries claiming significantly higher capacities are generally overstated.

The genuine Fujifilm batteries can fully utilise the camera and charger’s power management system. This means that all four battery contacts, [+], [T], [S], and [-], are functional. On some non-OEM batteries, the [T] and [S] contacts are either set at a fixed value, or un-connected to any appropriate circuitry. This non-functionality of the [T] (temperature control) could have safety consequences.

The genuine Fujifilm battery’s designation as a high performance “S” type, is reliable. Non-Fuji batteries can make this claim, as a pretense, by simply labelling them as an “S” type, and changing the resistance value on the [S] contact from 100kΩ to 680kΩ, without any other internal changes to the “non-S” chemistry or construction. (The camera will report this fake as an NP-W126S battery).

Production date, and so the age of the genuine battery, can be established with certainty. This can be very important for long term power management and planning. Also, if you are able to inspect a battery, before purchase, you could avoid purchasing old stock (bearing in mind that, for distribution and and logistics reasons, we could expect even the “freshest” batteries to be several months past their production date).

There could be warranty implications. If the camera was damaged as a result of a battery defect, obviously the question of whether the battery was a genuine Fujifilm battery, or a non-OEM battery, would be crucial to the outcome of any warranty claim.

Capacity against voltage profile is as expected by the system, so the battery level indicator works as it was designed to.

The relationship between, battery voltage, remaining capacity, and expected time before power is depleted, is non-linear. The discharge curve for the genuine NP-W126S battery differs from that of other batteries. Unlike the fairly simple curve of the genuine batteries, the discharge curve of the third party batteries tends to be more complex, with multiple inflections. Since the camera’s battery monitoring system is calibrated against the discharge curve of the genuine NP-W126S battery, the camera will not read the current capacity of other batteries accurately (unless the battery happens to have exactly the same discharge profile as the genuine NP-W126S battery). Unfortunately, this renders the X-T3’s ability to give detailed percent-remaining capacity information for non-Fuji batteries, not very meaningful.

Genuine NP-W126S batteries, and representative non-OEM batteries, were tested in order to establish the discharge characteristics against the battery level indicator. Each battery was fully charged using the supplied BC-W126S charger. When fully charged, the battery was removed and allowed to rest for 90 minutes, so that the open-circuit voltage could stabilise. The voltage was measured and recorded, and the battery was inserted into the X-T3.  4K video shooting was initiated. As soon as the indicator dropped by one bar (an “indicator event”), the video was terminated. The battery was removed immediately, and its open-circuit voltage measured and recorded. The duration of the video recording was used as a measure of elapsed time.  The camera and battery were allowed to rest for a 10 minute cooling time, before the battery was again inserted, and video shooting re-initiated, until the next battery indicator event. This process cycle was repeated until the eventual camera shutdown, due to depleted battery.

After testing, I differentiated the results into 3 groups, which I have arbitrarily called type 1 (the genuine Fujifilm batteries), type 2, and type 3. The results for batteries within each type group, have been averaged, in order to give a very generalised view of the discharge behaviour typical of that battery type. Please note that, because the testing placed the batteries under very high stress, the results could be considered as those of a worst case scenario. You may actually get better discharge behaviour than what these results indicate.

Because the battery level monitoring system of the X-T3 is calibrated against the genuine Fujifilm battery, the indicator symbols when using that battery, are informative, reliable, and accurate. Note that the remaining charge percentage and the remaining runtime percentage, don’t exactly match, because their relationship is non-linear.

Perhaps most importantly, the indicator gives adequate warning before system shutdown due to battery depletion.

These batteries are well regarded by some people, because they deliver similar capacity to the genuine Fujifilm batteries, but at only a fraction of the price. However, they have the least conformity to the X-T3’s calibration curve. Their actual degree of discharge is always higher than what is shown by the battery indicator, and this discrepancy increases as the battery discharge progresses. By the time the indicator displays 2 bars, the battery is almost fully discharged, and low-battery shutdown follows quickly, with little or no warning.

Notice that this type of battery may not display the one bar battery symbol, but goes straight from two bars to empty.

These batteries are low cost, and typically have capacities in the range of 1000 – 675mAh, (which may be overstated on their label, by up to 45%).  At the beginning of discharge, the actual charge remaining is slightly higher than indicated, then at about midway (3 bars) the display is fairly accurate, and finally, in the low number of bars, the actual charge remaining, is less than indicated. Due to the fact that the battery has a lower maximum capacity to begin with, full depletion is reached very quickly, when the indicator is in the low number of bars.  By the time the indicator displays 1 bar, the battery is almost fully discharged. If the low-battery warning is given, shutdown might follow within a couple of seconds.

Because of their lower capacity, these batteries tend to overheat when charging, (the charging current, which has been chosen for a 1260mAh battery, is too high for the lower capacity), and so these batteries often become swollen if the charger does not implement over-temperature protection.

Simply being a non-OEM battery, does not make a battery counterfeit. To be counterfeit, there must be an attempt to deceitfully pass (via fake packaging and labeling) the battery as a genuine Fujifilm battery. Suspicions regarding the battery’s authenticity generally arise from, low purchase cost, poor performance, or the experience of the battery having a tight fit in the battery chamber. The following anomalies, (a more comprehensive list can be found in NP-W126S COUNTERFEITS: A Visual Guide to Spotting the Fakes), can help distinguish counterfeit batteries from the genuine (manufactured for Fujifilm by Panasonic) batteries:

Check the dimensions of the printed area of the suspect battery against those of a known genuine battery. When the printed information on the genuine battery was scanned for the purpose of reproduction on the counterfeit, some re-scaling may have taken place, leading to a slight difference in the bounding dimensions of the information printed on the  battery.

Weigh the battery, with accurate electronic scales. Genuine batteries weigh very close to 47g / 1.7oz. Non-OEM batteries can be  anywhere in a range of about 42-50g.

Check the flatness of the printed sides of the battery. Genuine Fujifilm batteries have a concavity to the sides, which can be seen by placing a straight-edge against them, and viewing against a bright background. The concavity can even be felt by rubbing over the surface with your finger. The genuine batteries will not have flat, or convex (bulging in the middle) sides.

Check the production code information on the end of the battery. Possible anomalies include: non-existent code, non-conforming code, or code that is ink-printed (rather than engraved/impressed). [The accompanying photograph is a mock-up, based on what I have seen].

A counterfeit battery may not show all of these anomalies, but it is likely to show several of them.

Section – D


The Fujifilm VG-XT3 vertical grip (from this point on, simply referred to as the “grip”) is an option designed to facilitate use of the camera in “tall” or “portrait” orientation, as well as providing further power options to those given by the body alone.

The grip can be used with either two or one batteries, or even without batteries, (if you want the “tall” format ergonomics, but don’t need the weight of extra batteries).  It can also be used, either attached to, or separated from the camera, as a dual battery charger. Charging takes approximately 120 minutes (when charging two batteries simultaneously) . Note that the Owner’s Manual (p. 247), states: “Use only NP-W126S batteries”.

For battery management reasons, you may sometimes want to prioritise a battery for discharge. As a general rule, the batteries are discharged starting from the left, and working towards the right. For light duty power demand, the three batteries are discharged in the following sequence: First, the left-hand grip battery, next, the right-hand grip battery, and finally, the body battery.

For sustained high power usage (continuous shooting, and high power demand video), the body battery supplements the power supplied by the currently designated-for-discharge grip battery, with the body battery being discharged at a lesser rate than the grip battery. The discharge sequence in this case is: First, the left-hand grip battery plus body battery, next, the right-hand grip battery plus body battery, and finally, the body battery.

You may be using a mix of batteries that differ in both type and age. The arrangement of the batteries in order of far grip battery to body battery, may have implications for your workflow. Also, certain battery arrangements could, if used for a long period of time, result in some batteries being under-utilised, and others being over-utilsed. For the sake of both efficiency and economy, it may be worthwhile putting in place an appropriate battery deployment strategy.

If using a mix of non-S and type-S batteries, it is recommended to place an “S” battery in the camera body. When the batteries are assigned this way, the camera can always have access to the highest performance type battery, even if the other two batteries have become discharged.

The exploitation strategy pushes your best (youngest) battery to the front of the discharge queue. This gives maximum usage value in terms of total lifetime shots against the purchase price of the battery. An advantage is that batteries are never under-utilised, and the strategy is very cost efficient. A disadvantage is that you can start with plenty of power at the beginning of a session, but the second and third batteries discharge more quickly than the first, so you may get less warning when all batteries having become depleted. It’s a good strategy if your shoot sessions are typically short.

The contingency strategy pushes your best (youngest) battery to the rear of the discharge queue. It considers the grip batteries as the working batteries, and the body battery as a back-up or contingency battery. Applying this strategy, when both of the grip batteries have become discharged, you should plan to replace or recharge them immediately, rather than continuing to photograph and running down the body battery. This strategy helps to ensure that you always have reserve power, so that you don’t lose power at some critical point in shooting, and also avoids having to regularly remove the grip to change a flat body battery, during the shoot. In this strategy, your “best” battery, is being kept in reserve, to ensure that you are able to cope with any unforeseen circumstances. The down side of this strategy is that the “contingency battery” may be under utilized during its typical two years of life expectation. Of course, whenever a new battery is purchased, it takes the place of the reserve battery, and the old reserve battery can be places in the grip as a working battery. This usage strategy is good for long shooting sessions, where you typically have to do battery replacements during the shoot.

This strategy distributes the usage over each of the batteries, so that none of them become overused or underused. This strategy is particularly recommended if you typically don’t remove your batteries from the camera and grip (that is, you use internal charging methods). The position of each battery in the system is rotated on a regular interval basis. An ideal interval would be a monthly cycle.

In a (say) five battery system (one in the body, two in the grip, and two spares), the two additional batteries can also be inserted into the rotation sequence, but you may have to do some record keeping, so that you can determine the correct sequence at rotation time. Be aware that, if all of the batteries were of approximately the same age, at the beginning of this strategy, they will all start to show signs of aging (decreased exposure counts) at approximately the same time (about two years on). So this strategy works better if a new battery is purchased at regular intervals (say, at the end of the first year, and then every six months), which should not be an unreasonable demand if working professionally.

A DC power input socket (EIAJ-03) is under the rubber seal on the left-hand side of the grip.

This socket is intended for the AC-9VS power adapter, that is supplied with the grip, and which can be used for both charging and supplying operational power, although not simultaneously. When the camera is turned off, the 9 Volt input will supply power for charging the grip batteries (but not the body battery). If the camera is turned on, then the 9 Volt input will supply power for camera operation.

The camera can operate without batteries if powered via the 9 Volt input, although to attain the camera’s highest performance, it may be necessary for the DC input to be supplemented by some battery power, (at least one partially charged battery).

There is the possibility of supplying 9V power using power sources other than the AC-9VS. The grip’s DC input is a standard socket complying with the relevant Japanese standards, and accepts an EIAJ-03 plug.

This socket is not compatible with plugs adhering to the other common standard, which is IEC 60130-10, although one of that standard’s plugs will loosely fit the socket in a way that is neither secure nor reliable. If using a 9 Volt power source other than the AC-9VS power adapter, it may be necessary to make up the appropriate cable (soldering and polarity discrimination skills required), in which case, the proper camera-end plug can be identified from the following table:

If searching online, the plug will typically be identified as a 4.8 x 1.7 mm plug. The “signature” yellow plastic tip, while common on the EIAJ-03 plug, is not unique to it, nor is it required by the standards. (In fact, Fujifilm uses a black plastic tip). However, the yellow tip can be a useful indicator of possible-candidates when searching for an appropriate plug.

Section – E


The NP-W126S and NP-W126 batteries are constructed of two series-connected metal-can type prismatic lithium-ion cells, together with a built-in power management board, all of which is sealed in a plastic case. (In what follows, “lithium-ion” will usually be abbreviated to “Li-ion”). The exact chemical composition of the NP-W126S battery is proprietary information. However, some information can be gleaned from Safety Data Sheets, lodged for the purpose of compliance with international transport regulations.

The exact transition metal component of the positive electrode is not openly specified, but the candidate metals are: Co, Mn, Ni, and Al. In what follows, specific information that was available from Fujifilm and from Panasonic Energy in Wuxi (the battery’s normal manufacturer), is supplemented by information which applies to Li-ion batteries in general.

The following information is intended to assist you rather than burden you.  In real life practice, it is not possible to follow all of the best advice, all of the time. We should differentiate between occasional sub-optimal battery treatment, and habitual misuse. Since the battery has a limited life regardless of how carefully it is treated, there is little point in becoming obsessive-compulsive in regard to maximising battery life.

There are two commonly quoted Li-ion battery states that may both be expressed as percentages.  One is the battery’s State of Health (SoH), and the other is the battery’s State of Charge (SoC).

State of Health is a ratio of the battery’s present capacity for storing energy, compared to the battery’s original capacity at the time of manufacture.  SoH speaks to whether the battery is, viable for continued usage, or approaching the state of being considered a dead battery.  The expression of SoH as a percentage is more conceptual than practical, because the user usually doesn’t have an instrument to directly measure the SoH, and it is typically inferred from the battery’s age and performance. By definition, the battery’s capacity when new will be 100%, but this percentage will decline with time and usage.  We are typically interested in the range from 100% to 80%, because when the SoH reaches a conceptual 80%, there is a noticeable fall-off in battery performance.  For the photographer, this fall-off generally manifests as a reduced number of shots per charge, and around 80% is a typical point at which we might consider withdrawing the battery from primary service, and replacing it.

State of charge is a ratio of the battery’s present actual deliverable energy, compared to its present potential for holding deliverable energy (which is, of course, largely dependent on the battery’s SoH). State of Charge is what is displayed by the camera’s battery level indicators. When fully charged, the SoC is 100%, but when “flat”, the SoC would be reported as 0%.  Keep in mind that 0% is relative, and does not mean absolutely zero energy.  Li-ion batteries cannot tolerate being at very reduced voltages, and so a certain amount of electrical potential must always be reserved, to keep the battery in a safe electro-chemical state.  This reserve is handled automatically by the camera’s power management system, and generally need not be a concern of the user.  But, as a consequence of this reserve, not all of the battery’s electrical energy is available for use by the camera.

To summarise, a flat battery will have a low State of Charge (say 0%) and the remedy is to re-charge it, while a dead (or dying) battery will have a low State of Health (say 80%) and the remedy is to replace it.

As a general rule, Li-ion batteries do not suddenly “die”, but rather, they show a gradual decline in capability. Within the context of that decline, we can broadly identify a transitional phase when the battery’s performance goes from meeting expectations to failing to meet expectations. We can consider the service period up to the “failure to meet expectations” point, the life of the battery. The Li-ion battery’s life inevitably declines due to two processes known as calendar fade and cycle fade.

Calendar fade refers to a time related decline in capacity, which is independent of charge-discharge cycling, and which even affects batteries that are not being used.  (Note that calendar fade is also accelerated by high temperatures, so it is beneficial for batteries to be kept cool).  The commonly accepted rule of thumb is that, after 2 years, a Li-ion battery can only hold 80% of its original capacity.  In general, at 80% capacity, although the battery is still usable, it is noticeably under-performing.

Cycle fade refers to an in-service related decline in battery capacity due to repeated charge-discharge cycling.  Fujifilm states an expectancy of 300 charge-discharge cycles for the NP-W126 class batteries (Owner’s Manual, p. 274). Again, capacity falling to 80% is the criteria for determining expected cycle numbers.

If we try to balance these fade processes by aiming for the calendar fade endpoint and the cycle fade endpoint to coincide, (300 cycles distributed over a period of 24 months), we are looking at roughly 3 charge-discharge cycles per week, for a single battery.  We can consider this as a hypothetical standard-usage-density for the purpose of determining whether the battery is being over or under utilised.

The Owner’s Manual (p. 28) states: “The battery is not charged at shipment.” New batteries are delivered with approximately 30% SoC. This is partly to extend service life by keeping the battery in a preferred storage state until the user has taken delivery of the battery, and partly due to transport regulations, (specifically, transportation by cargo aircraft under UN3480, Class 9 Dangerous Goods category, with state of charge not exceeding 30%), since Li-ion batteries are safer (less likely to enter a thermal-runaway condition if subjected to elevated temperatures) at a lower SoC. The new battery may have to be charge and discharge cycled about three times before it gives normal charge and discharge behaviour.

The following situations or conditions should be avoided to ensure that the Li-ion battery is not un-necessarily stressed.

• Avoid high temperatures (should not be subjected to > +45°C or +113°F)
• Avoid ultra-fast charging (Rate of charge greater than 1C)
Absolutely avoid charging at temperatures below 0°C.

Li-ion batteries are charged according to the constant voltage (CV) / constant current (CC) method. The charge process has two main phases. In the first phase, the current is constant, at a value determined by the selected C-rate, the voltage steadily climbs, and the increase in charge, over time, is linear and rapid.  In the second phase (saturation phase), when the maximum charge voltage (8.4 Volts) has been reached, the voltage becomes constant, the current drops rapidly, and the increase in charge, over time, becomes non-linear, and slower. If charging is being monitored, the rapid drop in current is a good indicator of the position in the charge process. Charging terminates when the current drops below a threshold (0.1C is typical).

Battery charging times are mainly dependent on ambient temperature and charging rate. Charging rate, or C-rate, is the expression of charging current normalized against battery capacity. For example, when charging with a rate of 1C, a 1200mAh capacity battery would be charged at a current of 1200mA, and would be fully charged in 1 hour (theoretically). Note however, that a rate of 1C is considered to be higher than optimal, and the recommended fast charge rate is 0.7C. Because very high rates of charging are detrimental to the long-term condition of the battery, high-rate charging is usually terminated earlier in order to avoid detrimental effects. As a consequence, the available capacity changes per different C-rates, with the higher C-rates typically producing slightly less available capacity.

The X-T3’s different charging methods use different charge rates, and as a result, have different charging times.  Of the three endorsed charging methods, charging via the grip uses the highest rate, and can charge two batteries simultaneously. Charging via the camera body’s USB port has the lowest charge rate and, although the slowest method, is probably the best for the battery, both in terms of available capacity, and long-term battery health.

Note that charging times of internal charging via the X-T3’s USB port, may vary according to the capability of the USB source, and whether the connector of the supply source is USB-A, USB-C, or USB-C PD (indicating the Power Delivery function). (I will update this, as more information becomes available).

Li-ion batteries do not have any significant memory effect, so there is no absolute requirement for Li-ion batteries  to be fully-cycled on a regular basis.  They can be partially cycled, but be aware that the various part-cycle patterns can differ in their beneficial or detrimental contribution to long term battery health.  Ironically, (and different from many other battery types), the “fully charged” state is more stressful to the Li-ion battery than lower states of charge, and leaves the battery more susceptible to electrolyte oxidation, which is cumulatively detrimental to its life, each time the fully-charged state occurs. Therefore, full cycling (fully charge, then fully discharge), is preferable to “top-up-to-full” partial cycling, because, in the long run, it results in fewer instances of being “fully charged”.

If you know that a shoot will only require a small number of shots, (perhaps a couple of dozen), then there is no problem with giving a discharged battery a shorter charge , say 40 to 60% of full capacity.  Routinely charging the battery to slightly less than full capacity (90% would be ideal), has a beneficial effect on battery longevity. However, the reduced number of shots per charge is not acceptable to most photographers.

Automatic chargers should implement protections against over-charging, and the camera should implement protections against over-discharging.  The battery also has its own internal protective circuit to guard against over-discharging.  Limits are according to the following significant voltages:

Although there are automated systems in place to guard against over-charging and over-discharging, poor usage practices can effectively put the battery slightly into the over-charged / over-discharged state. Slight over-charging can result from repeatedly putting an already fully charged battery back on the charger.  Slight over-discharging can result from repeatedly turning on again, a camera that has displayed the battery empty sign and automatically switched off.

Li-ion batteries are noted for their wide range of operational temperature compared to many other battery types, however, they are very sensitive to temperature beyond that operating range.

As temperatures become elevated, initially the battery sustains internal damage which impacts its long-term performance, then at very high temperatures, the battery starts to sustain damage which can pose serious safety risks. Li-ion batteries contain flammable electrolyte that may vent, and spontaneously ignite when subjected to temperatures above +150℃ or +300°F. When ignited, Li-ion batteries can burn rapidly with flare-like burning effect, and may ignite other batteries in close proximity.

After a full charge, the open-circuit voltage of the battery (as checked with a multi-meter) will decrease rapidly in the first 10 minutes and then gradually over the next few hours before stabilising.  If you intend using voltage as a guide to battery condition, rest the battery for 90 minutes after charging, before measuring the voltage.  The stabilised voltage is a better indicator of SoC than the voltage measured immediately after charge termination, and you are likely to get better power metering by the camera if you begin using the batteries after they have stabilised.  This supports the practice where, if you have to charge batteries for a shoot, it is preferable to charge them the night before the shoot, rather than immediately before the shoot.

If you have the requisite background knowledge, and are comfortable with using a digital multimeter (DMM), you can use the battery’s open-circuit voltage as a surrogate for battery state and condition. Since these measurements do not assess the battery under load, they cannot account for load related voltage drop, however they are useful in giving further information for battery assessment and comparison. It should be noted that instantaneous voltages during charging, and instantaneous voltages during discharging display hysteresis. That is, they follow different curves, showing discrepancies in the region of up to half a Volt, with lower voltages presenting for the discharge curve. Therefore, voltages during charging and during discharge are not suitable for comparison.

When doing these static measurements on the battery, the only contacts of interest will be the positive and negative contacts. For measuring the open-circuit voltage, set the DMM to DC voltage measurement, and make contact with the probes for just enough time to get a stable reading. Measurements should be made to the nearest tenth of a Volt.

The NP-W126 class batteries have four gold-plated electrical contacts, marked with [-], [S], [T], and [+] symbols.

The [T] contact pertains to temperature management, and should connect to an NTC (negative temperature coefficient) thermistor, with a nominal resistance of 10kΩ at 25°C (±5% or better, typical). The resistance of the thermistor drops (with a non-linear output) as temperature increases. [To give an example: The NP-W126S battery was temperature stabilised at the room temperature of 15°. The resistance reading from the thermistor was 13.5 kΩ. Then, the battery was placed under the armpit for 5 minutes, to warm it. After warming it, the thermistor reading was found to have dropped to 9.5 kΩ].  The thermistor allows temperature monitoring while charging. Li-Ion batteries typically increase 5°C (9°F) in temperature during charging, as a normal consequence of the chemical process involved. But, the battery should not be allowed to increase more than 10°C (18°F) during charging, nor is charging allowed at more than 45°C, or less than zero°C, in order to avoid shortened battery life, lithium plating at the anode at sub-zero temperatures, and over temperature hazards such as battery swelling, venting, and thermal runaway.

When attempting to charge the NP-W126 class batteries, in the X-T3 camera, or either of the two Fujifilm chargers, if a resistance indicating a temperature within the safe range is not seen at the [T] contact, then charging is not initiated. (This safety function is also implemented on the Nitecore FX1 USB charger). On non-OEM batteries, the [T] contact is usually just connected to a fixed 10kΩ resister (meaning that it always signals the temperature as OK, even if it is outside the acceptable limits). This allows the batteries to be charged, without adhering to the safe charging temperature protocols.

The purpose of the [S] (probably standing for “Status” or “System”) contact is not openly documented. Although we could speculate that it might be for a single-wire smart system (there is little evidence to support this idea), it is most likely a simple system indicator, that gives battery information by whether or not a measured resistance exceeds certain thresholds. Such a method is expandable over time, so that if a new further improved battery became available, another higher resistance threshold can be added to the system, to indicate that battery. Note that the X-T3 camera differentiates between “S” and “non-S” type batteries, by interrogating the resistance on this [S] contact.

Typical self-discharge rates for Li-ion batteries (at a temperature of about 20°C) are 5% in the first 24 hours after charging, and then 5% per month (this monthly five percent is made up of approximately 2% intrinsic loss, and 3% due to drain by the battery protection circuit).  As a rule of thumb, the self-discharge rate doubles with every 10°C increase in temperature.

Sometimes, we may wish to intentionally either partly or fully discharge a battery, for example, for testing purposes, or in preparation for storage.  The X-T3 camera does not provide a specific discharge function (Some cameras do, for example Samsung NX1).  For the X-T3, the best way to discharge the battery is through normal usage, just by taking photographs or video.  There may be situations where your purpose is only to take the battery’s SoC just out of the fully-charged zone (one of the more stressful states of battery condition).  For example, you may have charged the battery in anticipation that it would be used, but it turns out that you won’t be needing it, and the battery faces an extended period of non-use.

In such a case, you can slightly discharge it by the following method.  Put the battery in the currently assigned discharge position (the left-most position if using the battery grip), attach the supplied EF-X8 shoe mount flash unit to the X-T3, and take a few shots using the flash. The EF-X8 has to be used, since it draws its charge power from the X-T3 batteries. (Incidentally, occasional use of the EF-X8 flash, is good for the X-T3’s flash capacitor, and helps to keep it “formed”). Another method is to take some video at a high frame rate and resolution (it doesn’t need to be 4K video). It is not recommended that you discharge by taking long duration continuous-shooting bursts using the mechanical shutter, because this will cause unnecessary wear-and-tear on the shutter, which although rated at several hundred-thousand actuations, never-the-less has a limited lifetime.

Conditions of storage (an extended period of non-use) have an impact on the life expectancy of the battery. The most significant factors are, the battery’s State of Charge (SoC), and the ambient storage temperature.  A Li-ion battery’s state of least stress is about 40% SoC at 15°C (59°F). This is represented by 2 bars on the X-T3’s battery level indicator.

If the battery will not be used for several days, or even a week, this period can be considered normal down-time, rather than a storage period. The battery can be left in its present state of charge, although leaving it in a fully charged state is not ideal, and should not be a target for a regular down-time state.

If it is estimated that the battery will be in a storage condition for a few weeks, “half-charged” is an appropriate level.  However, it is also OK to leave the SoC at an effectively “flat” level.  A battery which has just gone flat (according to the camera), is still well above any damaging over-discharge voltage. An ambient temperature of +15°C is optimal, but since the period of non-use will be short, a storage temperature in the range -10 to +40°C is OK.

If it is estimated that the battery will be in storage for a period of months (this could happen if you were going to be away from home for an extended period of time, and you are taking a different camera with you), it is recommended to have the SoC of the stored battery at 40 – 50%, indicated by between 2 or 3 bars on the X-T3’s battery level indicator.  This places the battery in a low stress condition, but also allows for inevitable self-discharge (about 5% per month) to take place, without the battery over-discharging. The battery should not be stored in the camera, due to further discharge by quiescent current. (Quiescent current flows due to the camera awaiting any wake-up signal from the power switch, and also from powering the clock-calendar). An alternative method of assessing a battery’s readiness for storage is by measuring its voltage.  A battery in good condition will have a stabilised open circuit voltage of about 7.6 Volts when its SoC is about 40%.

If initially stored at 40% SoC, after about 8 months the battery may be close to flat, so it would be good if the stored battery could be given a part charge (back to 40 – 50%), say about every 3 – 6 months. At any rate, a battery should be charged at least once per year. A storage temperature of +15°C is optimal, but up to +25°C is acceptable, however it is not recommended to store the battery outside the range of 0 to +35°C.

Keeping the battery’s gold-plated contacts clean can help attain optimal charging and usage conditions.  Contacts can become dirty from inadvertently touching them, or simply by the deposition of air-borne grime (particularly in cities, where the presence of diesel fuel particulates and other pollutants can be significant).  A cotton-tip is useful to buff the contact surface. No liquid or solvent should be used.

Keep in mind that there are numerous contacts in the power supply chain, and they all need to be kept clean. However, be very careful not to catch and bend any spring contacts.

For the purpose of battery management, it is useful to be able to identify each individual battery, by labeling them. No stickers should be attached to the sides of the battery, due to the possibility of jamming in the battery chamber.  A convenient place to write (using a fine tipped permanent marker), a number, letter or symbol for individual battery identification, is the orange orientation patch (square or circle) at the end of the battery. The manufacturing year and month code letters are convenient identifiers. Unless several batteries were purchased at the same time, and they came from the same production batch, the production codes are likely to be unique, for each of your batteries.

If you have to use non-OEM batteries, you can put a small sticker in the same position as the NP-W126 class battery’s orange orientation patch. Since you probably won’t know the production date of the battery, you can arbitrarily assign it a production date three months prior to the purchase date, (this allows for some shelf time with the vendor, before purchase). You can give it  year and month code letters, according to the Fuji system, so that any management records follow a consistent method.

A battery is effectively dead when the photographer rejects it due to poor performance.  A battery that has been used properly does not suddenly cease working, but it does eventually reach a point where its performance no longer meets the requirements of the photographer.  This point will differ slightly from person to person, depending on their usage style and workload demands.  Specific signs of a dead or dying battery are:

• Uncharacteristically long or short charging times
• Very rapid self-discharge
• Noticeably decreased number of shots per charge.

Based on the typical signs of a dead or dying battery, the photographer will develop a feeling about how a particular battery is doing. However, this type of assessment can be very subjective. A more objective criteria of the battery life condition (State of Health – SoH) can be obtained from the stabilised (90 minutes after-charge) open-circuit voltage.  It is not possible to give a universally applicable look-up-table (LUT), because battery usage routines (as well as user expectations), and local environmental conditions, will cause variation in the typical voltages reflecting the various states.  However, it is possible to compile your own personal LUT over time, if you are prepared to take measurements and keep records.  A SoH look-up-table, may be similar to this:

This method is useful if you want to keep records, for comparison, of battery condition at regular intervals, because it yields a number.

A convenient way to keep records of battery condition is a battery audit form. This could be either on paper, or a computer spreadsheet. On the form, you record the open circuit voltage (90 minutes after charging), of each battery.

This is done at regular intervals; three monthly (that is, four times a year), would be an appropriate interval. Just do it sometime during the designated month – it is not necessary to do it on a specific date. The form also allows you to record the reaching of significant voltage thresholds (based on the SoH look-up table).

A PDF file of the audit form can be downloaded here: Battery-Audit-Form.PDF

Batteries that are beyond the two year or 300 cycle stage, although no longer in their prime condition, are still useful. While the best batteries are kept for operating the camera at its top performance (primary service), the aged batteries can be assigned to secondary service tasks. Such tasks include:

• Back-up batteries
• Batteries for short or low shot count sessions
• Hold-over batteries

Hold-over batteries are useful if you recharge all batteries directly after a shoot, in readiness for whenever the next shoot will occur. If the camera is left unused for days or weeks, the first battery in the discharge sequence will lose some of its charge (due to quiescent current, waiting for power-up signal, and maintaining the clock and calendar system). That same battery would maintain more of its charge over the same period of time, if not left in the camera.  To avoid this “stand-by” discharge of the battery, when you are not using the camera, you can replace the first battery with an old battery, and just swap in the newer (still well charged) battery, before the shoot.

“Just in case” and “Just in Time” (JIT), indicate two different approaches to what “triggers” you to recharge your camera batteries. Should you recharge them immediately after a shoot (so that they are ready to go), or should you leave them in their post-shoot state, and recharge them just prior to the next shoot? There is no universally correct answer, because it will depend on your usage style, workload demands, and also your ability to know in advance when the next shoot will be, or even to exercise your own discretion about when shoots will occur. Keep in mind that, when a Li-ion battery has gone flat during a shoot, there is no problem leaving it in that state for some days, or even weeks (just let it have some “down time”). A Li-ion battery is very different from a lead-acid car battery, which should not be left in a discharged state. However, as to the long term affects on battery life, it is probably more beneficial to, where possible, let the immanence of usage be the trigger for recharging (just in time), rather than letting the conclusion of usage be the trigger for recharging  (just in case). This is because, with charging directly after the shoot, if you wait some time before the next shoot, the battery has been left longer in a fully charged state (not optimal for battery longevity), and you are likely to give the batteries a top-up charge before the next shoot anyway. This results in more charging than is absolutely necessary.

Battery cases are useful in order to protect against accidental shorting of the power terminals, and also, give a convenient means of distinguishing between charged and discharged batteries. New NP-W126S batteries, when purchased as an accessory, are supplied with a plastic soft pouch.

However, if you would like a hard case, those designed to fit the Nikon EN-EL9 battery, are suitable (although slightly longer than necessary). You can cut some dense (non-conductive) foam plastic to fill the extra length, and stop the battery from rattling in the case. The internal dimensions of any suitable battery case, need to be at least 47.5 x 36.5 x 16 mm.

If spare batteries are kept in a pouch, or battery boxes, a simple method of distinguishing between charged and discharged batteries, is by inserting the batteries with the contacts facing either inwards or outwards, to signify charged or discharged. Alternately, if you use many batteries, you can have two battery pouches, one for charged batteries, and the other for discharged batteries.

If a Li-ion battery develops an internal short-circuit, this can be the prelude to a thermal-runaway event that eventually causes the battery to rupture or vent, and spontaneously ignite. Other triggers for catastrophic battery events include: faulty charging, accidental short circuit by contact with metal objects, use of the camera or batteries outside of allowable limits, and heavy trauma to the camera. The fuel for the ignition is the electrolyte content of the battery, rather than lithium metal. Although lithium metal reacts violently with water, lithium-ion batteries, contain very little metallic lithium. As a consequence of the sparse metallic lithium content, water is a suitable and recommended extinguisher for burning Li-ion batteries, such as the NP-W126 types. There are two goals in extinguishing a Li-ion battery fire: First, to extinguish the initial fire, and second, to cool the immediate surroundings to avoid the ignition of other Li-ion cells. It should be remembered that a single NP-W126 type battery contains two Li-ion cells, so the X-T3 camera and grip (3 batteries in total) holds 6 cells, and each one will ignite in series (with a delay of between several seconds up to several minutes between each ignition), if the local temperature is not significantly lowered. Water is the best medium for lowering the temperature. However, covering the extinguished batteries, even with ice cubes, is not recommended, because it tends to form an air pocket which traps and retains the heat, leading to re-ignition.

Section – F


Mirrorless cameras, such as the X-T3, are inherently more voracious for power than DSLR’s. The specific difference in power requirements is the mirrorless camera’s use of an electronic viewfinder (EVF), or continuous use of the LCD monitor. The key to getting power consumption that approaches that of the DSLR, is to configure the EVF and LCD monitoring system, so that they are not turned on more than they need to be.

The most power efficient View mode option is “EVF ONLY + Eye Sensor”, because it results in the viewing system being on for the least possible time. “Putting your eye to the viewfinder turns the viewfinder on; taking it away turns the viewfinder off. The LCD monitor remains off”. The view modes can be cycled through by pressing the view mode button on the right side of the EVF housing.

Try to set the Auto Power Off function to the shortest interval that you can comfortably work with. Wake-up from automatic power-off is achieved in less than one second by simply half-pressing the shutter button.

Auto Power Off and Performance settings are accessed through the Power Management sub menu of the Camera’s Set-Up menu. For convenience, the Performance (Boost) setting can be assigned to one of the function buttons. However, this is not necessary when the optional grip is used.

When the grip is attached, the “Performance” menu option, is greyed out, and unavailable, (to avoid selection conflicts) because the grip has its own dedicated performance (normal or boost) switch.

Unlike the X-T2 and X-H1 cameras, the X-T3 is able to realise top performance even without the optional battery grip. The high performance mode is called boost mode. When the highest performance is not needed, the camera can be set to Normal mode. In Normal mode, to conserve battery power, after ten seconds of inactivity (no button, dial, or touchscreen activation), the displays revert to a stand-by mode (low brightness, and very slow frame refresh rate). The display leaves this stand-by mode if there is a control activation event, or if the power mode is switched to Boost. There are no menu options for modifying this behaviour. However, if you are not using functions that that take a high power drain (continuous auto-focus, continuous high-rate stills shooting, and high resolution video), then leaving the camera in Boost mode should not produce any significant run time deficit.

According to the advisory message displayed when non-S type batteries are loaded, “Boost mode function is restricted”. The exact restrictions, for this situation, are still being compiled. (I will update this guide, as further information becomes available).

Section – G


BC-W126S / BC-W126
The release of the X-T3 was accompanied by the introduction of a new battery charger. The newer BC-W126S is the charger generally supplied with the X-T3 camera, although, the Owner’s Manual (page xix) states: “A BC-W126 battery charger may be supplied in place of the BC-W126S in some countries or regions”. The two chargers are interchangeable, and either charger can be used for either battery (NP-W126 or NP-W126S).

The two chargers differ in two main points: The method of connecting to the mains supply, and the slightly increased maximum output current by the BC-W126S. (Does the newer charger differentiate between the older NP-W126 and the newer NP-W126S batteries, when charging them? I don’t know yet, but keep in mind that the two battery types have a different resistance level on their [S] contacts, so the charger may differentiate, and charge them slightly differently. But, that’s pure speculation. I will try and test this when I make a break-out box for the charger.)

Some non-OEM chargers can deliver benefits not available from the standard supplied charger. Desirable features include:

• USB powered (greater number of source options)
• Status display (current state / charging progress)
• Simultaneous charging of several batteries

One very important factor, when considering non-OEM chargers, should be, whether the charger implements any kind of temperature monitoring, while charging. This will mean, either the ability to monitor the NP-W126S or NP-W126 battery’s thermistor (on the battery’s [T] contact), or the charger having its own built-in temperature sensor. Over-heating the batteries while charging will produce cumulative damage to the batteries (noticeable as as a decline in the battery’s performance, or as swelling, or even slight decrease in weight, due to loss of electrolyte if the battery has vented).

Section – H


The X-T3 camera has a USB type-C (USB 3.1 Gen 1) connection port.  As well as its data transfer function, the port can also be used to input 5 Volt power for charging the  battery in the camera body, or to assist powering the camera’s operation.

Because the X-T3 has tethered shooting functionality, connection of a USB cable can trigger unexpected camera behaviour, if the Set Up Menu’s “PC Connection Mode” setting is not appropriate. How the 5 Volt supply is utilised depends on camera mode (off, shooting, or playback), as well as the PC Connection Mode menu settings. If not tethering to a computer, a trouble-free setting is “USB Card Reader” mode.

The USB socket accepts a USB-C plug. However, depending on the type of device used for charging, the cable could be either a USB-C to USB-C, or a USB-A to USB-C cable.

According to USB standards, the X-T3 is considered a high power device, since it requires at least 500mA from the USB supply.

Since all of the USB standards from 2.0 onward can deliver at least 500mA (composed of an allowed maximum of 5 x 100mA load units, as defined under the USB standard), most USB compliant outputs meets the X-T3’s charge requirements.

The Owner’s Manual (p. 33) states: “Connect the camera directly to the computer; do not use a USB hub or keyboard.” Typical USB bus powered hubs cannot be used since, although they draw five load units (100mA each USB 1.0/2.0, or 150mA each USB 3.0), 1 unit is used by the hub controller, and the remaining 4 units are distributed among the hub ports (1 unit each for a 4 port hub). The available current from a hub port could be as little as 100mA, and probably not higher than 200mA, which is not sufficient for the X-T3’s charging requirements.

Power delivered via the USB port will charge the body battery, when the camera is switched off, however, it does not charge the grip batteries. Using the USB port, the time to fully charge a flat battery is about 300 minutes, or 5 hours. Ability to charge the body battery via USB means that the battery can be left in the body on a quasi-permanent basis, which makes it un-necessary to remove the grip in order to charge the body battery (an inconvenience of the X-T1 camera when used with grip).

When the camera is switched on, power input via the USB port, is used to supplement the power available from the battery.  Importantly, the camera cannot be operated independently (that is, without a battery installed) solely on power delivered via the USB port. Even if the USB 5 Volts was delivered at a 3 Amp current, that would only produce 15 Watts of power, which may not be sufficient for operation without a battery, since the X-T3 is rated at 18 Watts. However, during operation with the body battery installed, the USB supplied power can supplement the battery power, so that the battery does not run down, or is discharged only slowly.

The USB power can be delivered to the camera from a computer, an AC to USB adapter, a USB power bank, or an automobile USB outlet or adapter, etc.  However, DO NOT use any unregulated voltage supply at the USB port. The maximum allowable voltage of the USB standards is 5.25 Volts (5.0 Volts +5%), and this should be considered the maximum voltage allowable at the X-T3’s USB port. While the nominal USB voltage is 5 Volts, the allowed minimum is 4.75 Volts , although a device powered by the USB bus is expected to be able to operate with voltages down to about 4 Volts.

This small power adapter with integrated power plug, delivers 5 Volt USB power, up to 1.0 Amp, via a USB-A socket.



A power bank is an external battery pack that can deliver power for charging or operation of mobile electronic devices, including digital cameras. The power bank’s input and output are usually (but not always) via USB ports. Input ports (for charging the power bank) are typically Micro B type, or USB-C. Output ports (for drawing power from the power bank) are typically USB-A, or USB-C.  Since the USB Consortium maintains compatibility between different generations of USB implementation, either type can be used, as long as the correct cable is available.

Power banks allow portability and versatility. One big advantage is that the power they hold can be assigned to devices in an ad hoc manner (for example, to charge the camera, a smartphone, a tablet, etc, as needed). A second advantage is that they can help avoid “just in case” charging of camera batteries, because the batteries can be charged on location, if and as necessary.  Although it could be argued that there is little advantage in carrying a power bank and USB charger,  compared to carrying several pre-charged NP-W126 batteries,  the  price difference between a power bank and several genuine batteries may be the critical deciding factor.

Power banks that allow the batteries to be removed, offer many advantages:

• You can use the highest quality batteries, (You get to choose).
• Batteries can be replaced when their performance starts to decline.
• Batteries can be “borrowed” for other purposes (LED torch, for example).
• Spare set/s of fully charged batteries can be taken, on long expeditions.

The power bank shown above is loaded with Panasonic NCR 18650B Lithium-Ion cells. Due to economy-of-scale in their manufacture, you can probably get eight of these for the price of one NP-W126S battery. Their power (3340mAh capacity x 3.6 V nominal voltage), is approximately 12 Watt hours, per cell. The nominal power of the NP-W126S battery is (1260mAh x 7.2 V) 8.7 Watt hours. Based on these numbers, the power bank, when loaded with four NCR 18650B cells, could recharge an NP-W126S battery about 5.5 times. Alternatively, if the power bank is being used to power the camera (via the USB port), we could expect the camera to be able to operate about 5 times longer than if powered only by the X-T3’s body battery.

Although most common power banks are designed to deliver power according to USB standards (normally 5V), it is also possible to get multi-voltage power banks. These may be of interest to the X-T3 user, since the grip can be connected to a 9 Volt power bank for charging and camera operation, and the body (without grip) can accept the DC coupler powered by a 9 Volt power bank, for operational power.

Fujifilm is currently recommending:

Anker PowerCore Speed 20000 PD
Anker PowerCore+ 26800 PD power banks

These have both USB-A and USB-C sockets. Whenever USB-C PD sockets are provided, they should be used in preference to the USB-A or USB-C (non-PD) socket, because the USB-C PD can potentially deliver more current (a maximum of 3000mA, compared to 900mA by the USB-A socket).

Section – J


The DC coupler is a common method used by camera manufacturers to provide a camera with an optional DC power socket. The DC coupler replaces the normal battery, and can provide a virtually continuous and unlimited supply of power.

The cable exit-point is on the right-hand side of the battery chamber door. When the door is open, and the battery removed, you can use a finger-nail to pull up the rubber seal.  The seal is anchored, so that it doesn’t fully come away from the body.

After inserting the DC coupler, with the cable on the exit-point side, ensure that the cable feeds properly through the exit route, and close the battery chamber door. The camera can now be powered via the DC socket which terminates the DC coupler’s cable.  Remember to set the power Auto-Off setting to “off” to prevent the camera turning off automatically.

The Fujifilm CP-W126 DC coupler combines with the AC-9VS power adapter to power the X-T3. A further possibility is to use the coupler to connect an appropriate (9Volt) power bank, for field usage. The rating for the power supply to the DC coupler is 9 volts at 2 Amps (therefore, 18 Watt), and these specifications should guide the choice of a power bank.

• Camera operation over long periods of time
• Static operations where the camera remains in a fixed position
• Situations where an interruption of operation must be avoided
• Situations where camera operation is be left unattended / un-monitored

• Time-lapse photography extending over many hours or even days.
• Large volume copying (for example, books or documents) where the camera is mounted in a fixed copying rig.
• Surveillance photography, or wildlife photography, with automated triggering, such as a sound activated trigger, or laser trigger.

When DC coupler is used, since there is no battery in the camera body, if DC power is turned off for an extended period of time, the camera clock will be reset.  However, the camera should be able to keep its internal clock battery sufficiently charged if external power is connected at least every couple of days.

Due to the camera being tethered by a power cable, various safety issues must be considered, as a matter of priority. Possible hazards include those generic to the use of AC voltages, trip hazards from cords/cables, and possible topple-and-strike hazards from cable pulling against tripods.

Please note that the DC coupler cannot be used in the X-T3 concurrently with the grip, because when the grip is attached, there is no exit point for the coupler’s cable.  However, the DC socket of the grip makes use of a DC coupler redundant anyway.

Section – K


Alternative power supplies open the opportunity to use the X-T3 remotely from mains power for extended periods of time.

Access to a motor vehicle allows the use of a 12 Volt to USB converter, or even the USB power socket built in to the dash of late model cars. The output should be at least 1.0 Amp, but preferably more.

Small portable solar panels allow the opportunistic recharging of power banks, which can then supply the camera, as well as other remote location gear. Don’t ever connect the solar panels directly to the camera. Instead, use the solar panel to charge a power bank, and then later, you can use the power bank to charge the camera batteries (internally or externally). Many portable solar power-supplies, although they deliver power via a USB socket, have an output that is unstable and subject to interruption. The voltage can exceed the allowable USB voltage by several Volts (especially if the Sunlight is very intense), if not connected to a high-enough load to bring about the appropriate voltage drop. A removable battery power bank with high capacity batteries, should place enough load on the supply, that the voltage drops to within the proper range for charging the power bank. At any rate, a catastrophic over-voltage event damaging the power bank, or its batteries, is a small cost compared to the possibility of damaging the camera. Use an inline USB power meter, so that you can be sure of what voltages are being delivered.

A folding unit, like the one shown, can give some degree of power control in ultra-bright conditions, by not being fully opened. Fully opened in decent Sun, it can easily produce 5 Watts of power. At midday in the middle of Summer, at mid latitudes, and properly aimed, it can produce several Watts more.

Since high temperatures are not good for Li-ion batteries, the power bank or charger will need to be kept in the shade while charging. You can use a radiant barrier material (such as metalised mylar bubble sheet) to form a shade cone for this. The conical shape is used because it is easy to form, tends to be self-supporting and resists collapsing in on itself. The weight of the power bank or charger, placed within it, stops the cone from opening out.


If the Sunlight is not optimal, and if you have a removable battery power bank, rather than trying to charge the power bank, it may be more efficient to charge a single 18650 battery in a USB battery charger, and this battery can be swapped into the power bank when needed.

The solar charging system should not be set up near dried vegetation, due to fire risk. At times of extreme fire danger, it should not be left unattended at all. If you are on the move, and the Sun is at your back, you can do some charging opportunistically, by attaching the solar panels to your backpack.

Section – L


One of the most useful devices for power management is the in-line USB power monitor. This device can display instantaneous voltage, current, and power throughput, as well as accumulated or drained milliAmp-hours, etc. Some also allow time, voltage, and current limits to be set. This device is very useful for charging situations where either the charger or the storage device (such as power bank) does not have a detailed status display.

The displayed readings will reflect some discrepancies from losses due to the power monitor’s own processing and display and illumination, however the readings should be sufficiently accurate for our intended purposes.

Although the camera’s LED indicator shows charging in progress or charging completed, the camera needs to be switched on in order to get a more detailed indication of current SoC, and charging progress.

If a power monitor is inserted inline, it can continuously show the actual voltage and current. Voltage reaching maximum level (8.4 Volts) and fall-off in current draw will be the most useful indicators of the state of the charging process.

Section – M


Incorrect or inappropriate use of the X-T3’s power systems, could lead to damage or even destruction of the battery, camera, or other ancillary devices. Furthermore, catastrophic failure of the lithium-ion battery could lead to serious personal injury.

Before acting upon any information in this guide, the camera user should satisfy himself / herself that they are acting with due diligence.

This guide is a compilation of information that I collected for my own use of the X-T3 camera. I am making it available in the hope that some of the sometimes difficult to obtain information, may be of use to others. However I cannot guarantee the accuracy of all of the information given here. There is the possibility that some of this information may not be correct, despite my own good intentions and diligence. You, as the camera user, must verify this information for yourself, and decide whether acting upon it, is prudent and safe. I cannot be held responsible for any damage of injury.

Directives about powering the X-T3 are given in the Owners Manual. These directives include instructions not to use non-Fujifilm batteries and non-Fujifilm chargers. Usage that fails to follow these instructions, could have the consequence of voiding your warranty.


Powering the Fuji X-T3



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8 thoughts on “Powering the Fuji X-T3”

  1. Fabulous article! Thanks for all your time for research and awesome analysis and use-case suggestions. It’s so rare to find such in-depth, properly-researched info online. I hope you get lots of donations to support you to do more of this. This article saved me time and money, and was a pleasure to read as well. Thank you!

  2. Thanks Dom for a fascinating article, it has given me a lot of information that is hard to find elsewhere. I love the XT-3, and this is a change from the usual reviews. Great work!

  3. Wow, that is thorough!

    I was really interesting in seeing if Power Delivery is supported and how that would work. I suspect it isn’t and Fujifilm just suggested an Anker PD power bank because it’s one of the largest available but it would be pretty amazing to be able to fast charge batteries in a pinch. I don’t have a PD charger myself or I’d check on my X-T3.

    1. Hi Ed. Yes, this is an area where the exact details need to be teased out. On one hand PD does offer enormous potential, but on the other hand (at least in terms of internal battery charging), the C-rate is always going to impose a limit, with 0.7C being the fastest they would normally like to use. I also don’t have (yet) a charging device offering the full PD specification, but mainly because my current external power device (the TOMO removable battery power bank) is meeting all of my requirements. Thanks for reading, and for your comments.

      1. Speaking of USB, have you tried connecting the X-T3 to a USB C external hard drive? Or a smartphone? I’d love for Fuji to implement a way for me to transfer files off the SD card without a computer.

      2. Hi Ed. I’m looking forward to exploring USB-C a lot more, but most of my equipment is pre-C. I did try a transfer a card transfer from the X-T3 to a USB-OTG (“on the go”) external drive with limited success. That works with some cameras, and not with others. I’ll try again with the X-T3, and see if I can sort it out.

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