Need assistance, not sure if it's my batteries or charger?

Tdaras

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Hi,

I have an e-bike with 7 x 12v 20ah batteries and an 84v charger. I stored the bike for the winter in a heated basement although forgot to charge the batteries throughout. Now I plugged them in overnight but nothing charged. When I measure the voltage using a multi meter, I get a 4.87v measurement on each battery. Does that mean they are no longer good or could it be my charger as it was sometimes finiky?

Thanks
 

Nelson37

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Type of battery? Chemistry? BMS? Actual max voltage of charger? What actual evidence do you have that "nothing charged"??? Indicator lights
on charger? Meter reading on battery BEFORE charging? IDENTICAL voltage reading on ALL SEVEN individual 12V batteries?? Measured on each individual battery with all 7 disconnected from each other? This is virtually impossible. You are leaving out multiple significant details. Impossible to even guess what the HELL you have going on to start with, much less how to deal with it.
 

Tdaras

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Type of battery? Yimatsu Chemistry? Lead-acid

BMS? Actual max voltage of charger? 84 volts

What actual evidence do you have that "nothing charged"??? Charged it all night and nothing would work the next day, no lights on the dash

Indicator lights
on charger? Meter reading on battery BEFORE charging? IDENTICAL voltage reading on ALL SEVEN individual 12V batteries?? Yes

Measured on each individual battery with all 7 disconnected from each other? Yes

This is virtually impossible. You are leaving out multiple significant details. Impossible to even guess what the HELL you have going on to start with, much less how to deal with it.
 

Nelson37

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Actual max voltage of charger must be higher than 12 x 7, don't know specs for lead but higher than 12 per cell. 13 or 14V.

Could be toast cells, could be bad battery charger.

All 7 cells at exact same way low voltage, after sitting for a few hours after charging, and disconnected, is just not likely.

But, this is lead, which has completely different characteristics from Li-ion, and far, far too heavy, so honestly I do not know too much about it.

Check your charger actual output, get individual 12V charger to charge individual cells or units, test some more. Lead should not have a problem sitting through the summer, assuming no drain whatsoever.
 

Tdaras

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Thanks, much appreciated. Will try some of your suggestions.


Actual max voltage of charger must be higher than 12 x 7, don't know specs for lead but higher than 12 per cell. 13 or 14V.

Could be toast cells, could be bad battery charger.

All 7 cells at exact same way low voltage, after sitting for a few hours after charging, and disconnected, is just not likely.

But, this is lead, which has completely different characteristics from Li-ion, and far, far too heavy, so honestly I do not know too much about it.

Check your charger actual output, get individual 12V charger to charge individual cells or units, test some more. Lead should not have a problem sitting through the summer, assuming no drain whatsoever.
 
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