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MG MGB Technical - Battery noise?

Hello everyone
This may be a very silly question but should the battery on my car make a quiet fizzing/bubbling noise after the car has just been switched off? I have just changed the alternator to a rebuilt one (same model) and I suppose I have never really listened to the battery before.

Thanks

Matt
Matthew Crabb

Sounds like your battery is being overcharged - a very dangerous situation. Overcharged = overheated.
Joe Reed

What Joe says is possible ordinarily. But since you just changed alternators, presummably because the older one had a problem, I assume the battery was in a state of discharge and the new alternator is charging hard and fast--discharged cells will bubble when being charged and get warm. But, when the battery is fully charged, that has to quit. If you can measure the voltage across the battery terminals when the engine is running, and it's approximately 14.5 volts--everything is probably OK. Just keep close tabs on the electrolyte level for a while. If it keeps going down, the alternator is most likely overcharging, as Joe said.

Wayne
Wayne Pearson

Wayne,
The battery was almost fully charged by a battery charger (16 hours), and then fitted to the car, then the car started and ran for about 5 minutes. I then turned it off and it was then that I noticed the bubbling sound, it is a quiet sound, it's not boiling vigorously. The old alternator was discharging the battery overnight, the new one shows no such drain (measured with bulb wired in place of negative battery cable). I will borrow a volt meter from a mate and check the voltage as you suggested.

Thanks

Matt
Matthew Crabb

Sounds to me like the usual noise made by a battery being charged - which it is while the engine is running.
Chris Betson

This thread was discussed on 10/05/2002

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