General Battery overcharge?

[sledgehammer]

Is it possible to overcharge a car battery when using a battery charger? Having had mine on charge in the garage it sparks like crazy when i try and connect it!
Its like your connecting it the wrong way round.
I am baffled.... any ideas?

 

[jimbro1000]

If the battery was charged from completely flat *the wrong way around* then it would be possible that the terminals are now incorrectly labelled.

Alternatively if the plates in the battery were that distorted that they are shorting it would spark like crazy because you just shorting the charge leads together.

The simple answer is to get a multimeter on the battery and see what the polarity is and what the voltage drop across the terminals shows as. It should be about 12.4v for a good battery. Anything less than 12v is as good as a dead battery and obviously if the polarity is reversed it is likewise as good as dead.

There will be some sparking from a charged battery but not too much.