X-T4 Battery (NP-W235) // Nitecore FX3's calculation of the capacity
Aug 8, 2021
3
Dear all
For my brand new X-T4 (looks like a "wow" camera, will do a review as soon as I have some experience), I wanted an external charger. Obviously, I don't like the idea of in-camera charging.
The X-T4 shares the NP-W235 with the GFX series. A wise decision by Fujifilm IMO.
I simply cannot get hold of the BC-W235 charger. Nowhere. It is backordered everywhere. After having read this thread and a few reviews on Amazon, I went for the Nitecore FX3. Is is cheaper than the BC-W235.
Looks like it works fine. Most importantly, it has a battery temperature control (4 pins). The current (A) starts slowly, then unfolds, and gets dramatically smaller towards the end. Looks good.
But now I wondered about the capacity of the NP-W235. Just wanted to share this because I think I found out.
On the NP-W235 itself, I read "2200 mAh" and "16 Wh". Fujifilm says on their website, "This large capacity battery is 1.5 times that of an NP-W126S battery." (On my NP-126S, I read "typ. 1260 mAh min. 1200 mAh.")
OTOH, when the NP-W235 is full, the Nitecore FX3 says "1800 mAh". My X-T4 recognizes the batteries charged in the FX3 as "full".
So what's actually going on here?! Here comes my explanation: it's a matter of the voltage used in the calculation. Fujifilm calculates 7.2 V. Nitecore indicates a voltage of 7.0...7.2 V in the beginning and 8.4 V at the end of the charging process.
- 7.2 V * 2.2 Ah = 15.84 Wh (calculation used by Fujifilm)
- 8.4 V * 1.8 Ah = 15.12 Wh (calculation used by Nitecore)
So it's all good. No contradiction. It's the same. We're at about 16 Wh.
Comments welcome.
NP-W235: 7.2 V, 2200 mAh, 16 Wh
Nitecore FX3: 1800 mAh but 8.4 V (voltage not shown)
Regards,
Martin