Replace NiMH Cell

[john]

One of my 36v packs has been struggling to provide current recently. I checked the cells and found one was dead (0 volts) so I took it out. The pack now seems to work a lot better.

Does anyone have any thoughts on whether it is ok to charge this pack with a the standard (HP) charger when there are only 29 cells?

I've ordered an Ansmann 8000mAh cell from LinITX.com as replacement. Anyone any knowledge of these? It's dischange current may not be the best but I recon it shouldn't matter too much with just on cell.

[aaannndddyyy]

The same thing happened on my Ezee sprint NiMH when I got it, had no problems charging 29 cells with a standard charger. My NiMH cells sometimes false-peak, weather this is because of the 29 cells instead of the standard 30 cell I don’t no, If the battery pack is not warm to the touch, a false-peak has occurred, and the charge cycle should be re-started..

[flecc]

I've had no problems in charging anything from 29 to 33 cells with the HP charger John.

My Torq Radical 39.6 volt batterey is an eZee NiMh 10 Ah battery with three of those Ansmann 8000mAh cells added when it was 10 months old on the basis that the original cells would have lost some capacity in that time, and it's performed perfectly for over a year now.

I pre-charged the three cells before adding them to the charged battery, then ran it gently the first couple of times, neither fully charging or discharging it, to get the cells to gradually match. During the first month or so of use, the battery's performance increased as the cells settled in.
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[john]

That's good to know that you've used the same cells to good effect. At £5.43 inc VAT they seem good value too.

I was wondering how best to match the cell. I can see that it is good to avoid full charge and discharge at first but what is it that makes cells come into line?

[flecc]

I think it's just exercising the chemistry with the same conditions John. My guess was that this should gradually harmonise to some extent at least, and the results seem to have indicated that, judging by the progressive initial improvement.

The discharging use will also be likely to favour draining a higher potential, helping the process.
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