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wjvail

Key Veteran

Meridian, Mississippi

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So, as the title says, is there some reason I can't put a balance lead on a NiMh Battery?

A few weekends ago a friend lost a plane to a NiMh battery that false peaked. Over the years I've had batteries that needed multiple slow cycles to get them to function close to capacity. It got me to thinking - why not put a balance lead on a 4 or 5S NiMh?

I understand that by the nature of peak charging I won't be able to balance the pack while charging. But by using an external monitor I should be able to get a better idea of what the individual cells in a pack are doing. What good is a 4 cell pack if one cell is dead? LiPo batteries have spoiled me in that I've gotten used to seeing the performance of each cell.

I make my own battery packs (NiMh and LiIon) and it would be little extra effort to wire in balance tab.

Any thoughts?

Bill

"Well, Nothing bad can happen now."

08-06-2016 07:18 PM
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PilotPin

Senior Heliman

Indiana -- USA

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I don't see any reason it couldn't be none. Although I don't see the real good in it. The experience I have with nimh and nicad is that if one cell is on the bad side and you have the pack charged up the bad cell won't show up with a load test. Let it set a few hours or couple days and it will show bad. Or discharge it to test for capacity .

08-06-2016 09:12 PM
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JuanRodriguez

Elite Veteran

The Villages, Florida

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You can test each cell with a volt meter to ID the bad cell.....

Been there, done that and old enough to know better.....

08-06-2016 09:38 PM
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Rojoalfa

Senior Heliman

Punta de Mata, Monagas-Venezuela

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I understand that by the nature of peak charging I won't be able to balance the pack while charging
/
/

I came with that question too.

Delta peak is very low 3-5 mV...

When the algoritm fails?

/

Saludos cordiales,

08-07-2016 12:23 PM
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heli4ever

Senior Heliman

USA

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when i was running Nimh i would do cycle test on each cell for mah it needs to with then 10% of rated even new cells needs to be checked
when i raced 10th scale buggy with nicads this was a must to have matching Mah sets to get the best performance and long life so yes having leads is a good idea but i would not call it Balance leads more of a load checking leads you still need to charge it as a set but you can test each cell with load tester to get Mah and voltage drope but you would use this for testing not to field charging ive done this is the pass

witch you know
nicad/nimh charges by peak voltage drop at a constant amp

lipo uses constant voltage when the amp goes to 0 at a set voltage its done but you need to monitor each cell so one does not get to high of voltage balance leads

08-07-2016 11:10 PM
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