Discharging NiCd battery packs

Hello all-
How far down should one discharge NiCd batteries? My Triton charger says not
go go below 1.1V per cell for Tx and Rx battery packs. It doesn't seem to
be low enough to me. I've had good results for many years recycling
batteries by leaving the Rx and Tx on until the cells are nearly dead and
read very low on a battery meter.
1.1V per cell for a Rx pack is 4.4V total..I've flown my planes with volts
that low.
Comments? Advice? Flames?!
Swede
Reply to
swede
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As far as I know, the 0.9V/cell is still the accepted norm for a "dead" NiCd cell. I have regularly drained mine below that, but not at a high C rate.
Jim
Reply to
James Beck
Don't think it is as important to precisely measure the pack capacity as it is to spot a trend toward decreased capacity.
Seems to me if the pack will generate the right numbers down to a specific cutoff voltage (1.1, 1.05, 1.0, or whatever) it's good to use, and that the specific cutoff voltage in and of itself isn't all that critical, so long as the cycler is consistent.
When the capacity starts to shrink it's time to relegate the pack to non-critical use.
Pragmatically, 1.05 works for me, since that's cutoff for the Accu-Cycle Plus.
Cheers, Fred McClellan The House Of Balsa Dust
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Reply to
Fred McClellan
Everything you need to know about batteries can be found here:
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Reply to
Bill
Individual cells vary some, but when I have done discharge graphs when discharging at a 1C rate, a fully charged cell will drop to 1.2ish quickly then hold the 1.2 to 1.1 range for roughly an hour, when you hit 1.1v on a cell, the voltage falls off REAL fast. Based on that I never fly at 1.1v per cell.
swede wrote:
Reply to
Phil
That's what the discharge curves say. From full charge, there is a quick initial drop followed by a plateau that lasts quite a while. After the plateau there is a sharp drop, meaning you don't want to be in the air too long at that point. The 1.1 or 0.9 volt per cell isn't really an issue, as they are very close together on the discharge curve. It doesn't take too long (many mAh) to go from 1.1 to 0.9 volts. Personally, I don't fly at anything less than 4.8 volts (loaded measurement) on a 4-cell pack. I put it on a quick charger and in a few minutes I am ready to go again.
John VB
Reply to
jjvb
Swede- You can discharge a NiCd cell to zip without harming it. Problems arise when it is connected in series with other cells that are not discharged. In that case, the cell that is discharged will be reverse charged by the others, and that will cause damage to it. For example, say you run your 7-cell Tx battery down to 6.3 V (0.9V/cell). That could indicate each cell discharging at a rate equal to the others to 0.9 V, which is fine. Cell aren't created equally, however, so it could quite possibly represent 6 cells still at about nominal 1.2 V level (7.2 V total) that are applying a reverse charge to one that is fully discharged - bad news.
Abel
Reply to
Abel Pranger

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