Battery charger - terminals connected backwards

[menguin]

If a charger was connected backwards to charge a battery, could it possibly reverse the polarity? Making the -ve the +ve, and vice versa?

The battery I connected someone had put the red plastic cover over the -ve terminal... So I connected it up the wrong way (as the only markings for -ve and +ve are engraved under the terminals - not as obvious as the massive red plastic cover!) to charge up. Installed in car, and no power? It sparks like normal, but the car won't start. Any ideas guys?

[V8LM]

menguin said:

If a charger was connected backwards to charge a battery, could it possibly reverse the polarity? Making the -ve the +ve, and vice versa?

No.

[Mr2Mike]

If it's an intelligent charger then it won't do anything at all, so the battery will still be flat. If it's a basic charger then it is actually possible to reverse charge the battery to some extent, but it will probably ruin the battery (and your alternator diodes if there was sufficient charge in it).

[redgriff500]

If the battery was totally flat - yes you can.

[menguin]

Bugger. Looks like a new battery then. Tried it with another battery in her Micra, and all works perfectly!

[redgriff500]

Simply totally flatten it (with something other than a car, like a 12v bulb) and re charge correctly.

Can't promise it'll work but you have nothing to lose.