Short answer: divide 19.24Wh by the assumed input power and by an efficiency of 0.8, and a 10W dock slot takes about 2.4 hours, a 7.5W power bank into the body about 3.2 hours, 5W in-camera USB-C about 4.8 hours and a 15W input about 1.6 hours. All four are estimates, not fixed charging times. The compatible NP-W235 is quoted at 2600mAh, 7.4V and 19.24Wh, with 2400mAh and 17.76Wh as rated values; the original sits near 2200mAh and 16.2Wh. Once the energy is fixed, input power and conversion loss set the pace, not the cell.
What each route actually does
In-camera USB-C hands the job to the camera power circuit. That path is intentionally cautious. Current is kept low to hold body temperature down, and on most models the camera has to be off before a proper charge starts. While shooting, the body draws first and only the surplus reaches the pack, so with a cable attached the percentage can still fall. It stretches a session rather than refilling the battery.
A two-bay dock bypasses the camera. It converts the input into constant current and constant voltage for the cells and drives each slot on its own. Its real advantage is parallel work: one pack runs the camera while the other refills. Run both slots together and the total power is shared, so a pair takes longer than a single pack, which the estimates below leave room for.
A power bank only moves the supply to a place without a wall socket. Its protocol, the cable and the device downstream decide the real input power. It does not lift the current ceiling of the body or the dock, so buy one for where you charge, not for how fast.
The arithmetic behind the estimates
Every figure uses the quoted 19.24Wh as the numerator, divides by an assumed input power, then divides by an efficiency of 0.8 to get hours. The power values are assumptions chosen to make the arithmetic readable, the 0.8 is a single uniform factor, and the results are estimates rather than a fixed figure for any model. The constant-voltage tail and idle draw usually add ten to twenty minutes.
- In-camera USB-C while shooting, 5W assumed: 19.24Wh ÷ 5W ÷ 0.8 ≈ 4.8 hours.
- One dock slot, 10W assumed: 19.24Wh ÷ 10W ÷ 0.8 ≈ 2.4 hours.
- Power bank into the body, 7.5W assumed: 19.24Wh ÷ 7.5W ÷ 0.8 ≈ 3.2 hours.
- Power bank into a 15W dock, 15W assumed: 19.24Wh ÷ 15W ÷ 0.8 ≈ 1.6 hours.
| Method | Assumed input power | Estimated time (19.24Wh ÷ power ÷ 0.8) | Where it fits |
|---|---|---|---|
| In-camera USB-C, shooting | 5W (5V / 1A) | 19.24Wh ÷ 5W ÷ 0.8 ≈ 4.8 hours | One cable on location, topping up while shooting |
| Two-bay dock, one slot | 10W | 19.24Wh ÷ 10W ÷ 0.8 ≈ 2.4 hours | Home and hotel, rotating two packs |
| Power bank into body USB-C | 7.5W (5V / 1.5A) | 19.24Wh ÷ 7.5W ÷ 0.8 ≈ 3.2 hours | Travel shoots with no socket nearby |
| Power bank into dock | 15W | 19.24Wh ÷ 15W ÷ 0.8 ≈ 1.6 hours | When the dock accepts a 15W input |
Why shooting while charging is not a charging plan
The parallel advantage of a two-bay dock shows up on a shooting day. Fill both packs the night before, run one while the other waits, then top both up again in the evening. That rhythm is steadier than waiting on the camera port. The NP-W235 fits the X-T4, X-T5, X-H2, X-H2S, X-S20, GFX 50S II, GFX 100S and GFX 100 II, and the same rotation applies to all of them.
Habits worth keeping, and how many packs
For a travel day of a few hundred frames, two packs usually suffice. Video-first or long outdoor days are safer with three. Work backwards from the estimates above: the shorter the window you have for charging, the more sense an extra pack makes instead of relying on a fast top-up on location. Figures are on the NP-W235 compatible battery page, with pack sizes under Fujifilm NP-W235 batteries.
FAQ
Can in-camera USB-C reach a full charge while shooting?
The body takes power first, so under load the percentage may fall instead of rising. Treat it as a way to extend a session; switch off or swap packs to actually refill. The 4.8-hour estimate also leaves shooting draw out of the sum.
Do two dock slots charging together slow things down?
Yes. The adapter output is shared, so a pair takes clearly longer than one pack. On a tight evening, charge one first and swap before bed.
Will a power bank charge an NP-W235 faster?
No. The ceiling is set by the camera circuit or the dock, and a power bank only answers where you can charge. To shorten the estimate you raise the assumed input power, not the bank capacity.
Is it a problem to unplug before full?
No. Shallow cycles are normal use, so charge whenever convenient and skip the ritual of running a pack flat. For a full set to leave with, top up on the dock the night before.