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Overcharged Lead-Acid battery - what to do?

what is the voltage of a fully charged car battery

I just found my 12V Lead-acid battery hot and bubbling from a charger malfunction.

It was connected to a 3-stage charger, which has been topping it up continuously since several months, while the 12V battery was supplying a bank of small battery chargers with "uninterruptable" power for testing and comparison of hundreds of NiMH batteries (a few at a time).

It has all been going very well until today.

For some reason the 12V charger decided to charge at 10A irrespective of battery voltage. This went on for probably about 9hrs, but certainly for a minimum of 4 hours.

When I found it, the 12V battery was making bubbling sounds and had an external temperature of 50degC (in 26degC ambient temp).

One drop of (presumably) acid had come out of a hole which looks like a vent.

I had "LogView" running, so I know that the 12Vbattery voltage suddenly jumped from the usual 13.5V to around 16V, with a maximum voltage of 16.67V reached at some time. For at least 4 hrs the voltage bounced around between 15.7V and 16.6V.

The battery is about 2 years old but has gone through very few charge/discharge cycles.

The battery label:


Marine/RV Maintenance free

Continuous use / Deep cycle battery

Model Number: HCM31LSMF

830CCA 200RC 110AH

Do you think this battery has been severely damaged, or can it take that kind of abuse for a few hours?

Category: Bank

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