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mcvwuk

NiMH battery dead?

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Hi,

I have recently bought an Etronix Power Pal mini charger and an EP2000s NiMH pack.

When they were delivered I put the battery in my viper, reset the ESC, and ran the car up and down the garden to test it out.

After ten minutes or so of playing with the car (chasing the dogs etc LOL), it began to run slow so I removed the battery with the view of charging the battery.

I read the manual for the charger - which is about as useful as a chocolate teapot - but decided to discharge the battery before charging. I selected the 'auto discharge' program for the NiMH battery and it happily went about it's business. I stopped the discharge program when the battery was on 0.1.

After this I have not been able to recharge the battery at all. I either get a 'connection break' or 'Batt. Vol Bellow MinWorkVol (5.5V)' status displayed. Have I killed the battery, or is there something else I can try?

Thank you,

Mike

PXL_20210528_115922322.jpg

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Ok... After leaving it alone for 15mins or so it seems to be doing something (see pic). Is this normal or have I got a duff battery? Thanks again, Mike

PXL_20210528_121822076.MP.jpg

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It might have trickle charged it to get it up to a sensible voltage, hopefully now it will start to put some power in to it. It should be able to charge it a 2A and the number at the bottom left will tick up to something approaching 2000. 

 

Or just recycle the battery and get another. 

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I would see if one cell gets hotter than the others.  That's a tell tale sign of one cell gone bad.  

I've ruined many batteries by discharging too much.  You can never know how much is too much.  Technically you'd start damaging at about 0.8v each.  But cells are not equal.  That's the problem.  

5.5v total would be about 0.9v on average.  Since they are not equal, there is a chance that you've got 5 cells that are 1.1v each, and one dead cell at 0v.  That one cell is likely hopeless.  The voltage could have flipped. Meaning, negative became positive, and positive became negative.  Which is why it gets hotter than others.  If that happens, there is no fixing.  You have to replace that one cell.  It's just cheaper to replace the whole pack.  

I hope it doesn't come to that.  If it hasn't flipped, it might come back alive after trickle charging.  

 

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I find that if you discharge NiMH too far it can prematurely die.  Especially driving to the point your car was slowing down it  can mean one of the 6 cells was potentially empty.  

Unfortunately with sport packs you can't tell which cell is bad unless literally going by differences in heat per cell while charging.   

I use a timer off my radio (or iWatch) when using NiMH and stop driving long before the cells begin to dump.  Then let them rest over night before recharge.  

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I have the Venom version of that charger. I recently built some packs in a custom configuration for a friend.  The cells I used were new but very old... then I went to charge then with that charger... got the same error.  I bought a trickle charger and trickle charged them for a little... then tried again. They have been fine since. 

 

Dumb question... did you set the charge amperage to 0.1 AMPS? I would think for that pack you should be at 2.0.

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