# Batteries smoking when charging



## EVfun (Mar 14, 2010)

That is definitely bad. Sometimes old AGM batteries will vent a little when charging, but if you can see emanations that is WAY to much venting.

To charge old AGM batteries you will need a 12v charger to first charge them individually. Only then should they be connected in series. Any battery that doesn't measure at least 11.1 volts before charging is unlikely to recover to a useable capacity. Any battery that doesn't measure at least 12.0 volts before charging is likely to have some loss of stated capacity. After charging and a day of rest, any battery that read at least 12.6 volts is likely to have reduced capacity and increased internal resistance. 

Lead acid batteries are slowly damaged by not being stored in a fully charged condition. The lower the state of charge they are stored at, the more rapidly the loss of capacity.


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## Triggermann (Jul 22, 2011)

I can do that should I charge at 2amps at first or higher?


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## dtbaker (Jan 5, 2008)

Triggermann said:


> I started charging my batteries today in my first build with used parts,and one of them started smoking and bubbling out of the vent hole.I stoped charging right away.The batteries are 12v agm about 3 years old is this bad? or normal.


definitely NOT normal.
you probably should haul all your batteries to an auto store and have them tested and charged before re-wiring in series.


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## Triggermann (Jul 22, 2011)

Thanks guys I didnt think it was good but didnt know if it I could try to fix them buy reconditioning.


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## EVfun (Mar 14, 2010)

Triggermann said:


> I can do that should I charge at 2amps at first or higher?


I would start at 2 and see if the charger is happy after an hour. If they are charging fine then you should charge as fast as the charger allows. If they won't take a fast charge they are unlikely to work well in an EV, where they will see rather high peak discharge rates.


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## Triggermann (Jul 22, 2011)

Ummm good point my 12v charger will go up to 40 amp.The chargers I have for the truck will go up to 60 amp, but set up to charge all the batteries not just one.


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## dtbaker (Jan 5, 2008)

I think you'll be safer letting an auto-store test/charge them for you in a nice enclosure in case one of them blows up.


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## Ziggythewiz (May 16, 2010)

60 amps is pretty high for a lead charger. How many ah are your batteries? Mine charge at 10, so I wouldn't be surprised at all if they smoked at 60.


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## Triggermann (Jul 22, 2011)

lol Im new to ev but not cars I have done body work for over 20 years. I have the right tools and know how to get it done. Thanks for your concern though.


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