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X-T4 Battery (NP-W235) // Nitecore FX3's calculation of the capacity

Started Aug 8, 2021 | Discussions thread
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Rightsaidfred
Rightsaidfred Senior Member • Posts: 2,179
X-T4 Battery (NP-W235) // Nitecore FX3's calculation of the capacity
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

 Rightsaidfred's gear list:Rightsaidfred's gear list
Fujifilm X-T20 Fujifilm X-T4 Fujifilm XF 35mm F1.4 R Fujifilm XF 18-55mm F2.8-4 R LM OIS Fujifilm XF 55-200mm F3.5-4.8 R LM OIS +5 more
Fujifilm X-T4
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