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Possible dead NIMH pack?

Possible dead NIMH pack?

Old 08-31-2009, 03:21 PM
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Questions?? Possible dead NIMH pack?

Early this year I bought my kids a 1/10th Losi Desert Storm and a 4200mah battery pack made up of Intellect cells. About 6 weeks ago it appeared the motor died while my 7 year old was doing circles in low-cut grass. The ESC would rapidly blink when trying to apply throttle. I borrowed a motor from a friend and that one didn't work either. So I bought a new LRP AI ESC, recharged the battery and everything appeared to work fine. I turned it off and proceeded to put on the body. Unfortunately it wouldn't work again after turning on the power.

After some trial and error I've found that it will only run when the battery has been freshly topped off. Even a slight drain (200mah) will cause it to stop working. I did a complete discharge/charge cycle last night and found that the battery took almost 4900mah after being discharged to 1.0v.

Does this fit the m.o. of a dead cell?
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Old 08-31-2009, 03:29 PM
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You mean 1v. per cell I assume not the whole pack. check each cell for voltage. I would guess if it is a bad cell it's more than one.
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Old 08-31-2009, 03:31 PM
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4900mah in a 4200mah pack is a little high but not out of the realm of possibility. I'm guessing your charge rate was at or close to 4 amps to get it to take that much.
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Old 08-31-2009, 03:38 PM
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Originally Posted by racer1812
4900mah in a 4200mah pack is a little high but not out of the realm of possibility. I'm guessing your charge rate was at or close to 4 amps to get it to take that much.
Yes, I was charging at 1C. Other than taking the pack apart, is there a way to test each individual cell?
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Old 08-31-2009, 03:44 PM
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Old 08-31-2009, 04:12 PM
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Originally Posted by mthird
Yes, I was charging at 1C. Other than taking the pack apart, is there a way to test each individual cell?
Is it a stick pack (2 rows of 3 cells end to end) or is it a a side X side pack? use a volt meter to check the voltage in each cell. If it's a stick pack there is no way to check each cell with out taking it apart.
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Old 08-31-2009, 04:44 PM
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Originally Posted by racer1812
Is it a stick pack (2 rows of 3 cells end to end) or is it a a side X side pack? use a volt meter to check the voltage in each cell. If it's a stick pack there is no way to check each cell with out taking it apart.
It's 6 cells side-by-side.
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Old 08-31-2009, 04:46 PM
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Fresh off the charger all the cells will probly read voltage and all might be the same. run it for a while and then check the voltage on each cell again the dead cells will read 0.0v probly. You don't need to run it real long to find the dead cells. From what you said it won't run long anyway.

Obviously you'll need to cut off any shrink wrap that may be on the pack to do this.
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