How much overvoltage can a car battery take?

[shouldbworking]

My Puma seems to have decided to throw a bit of an electrical wobbly. When driving I get intermittent traction control lights (one for the Accelera tyres thread perhaps as they are on the driven wheels), and intermittent battery lights. At night you can see the lights brighten every so often for 2-3 seconds before returning to normal.

It started doing this on monday, and is booked in to the garage next tuesday. I'm assuming the voltage regulator is shafted, just wondering about using it in the meantime - anyone had any experience of this kind of fault - if I use it for commuting I'm wondering about the risk of the battery exploding. It's only maybe 20 or 30 seconds of overvoltage per journey, and it gets to sit around for 8 hours before commuting back, so presumably plenty of time to vent any hydrogen buildup?

Cheers in advance

[alangla]

Dead simple test for this - stick a multimeter across the battery terminals. It should read 12-13 volts. Fire the engine up, then increase the revs. The voltage should be steady around 14 (IIRC), if it varies with the engine revs then the reg is goosed.

Also, if you get a whiff of rotten eggs, you're cooking the batt - shut off immediately.

If you don't have a multimeter, some recent cars have a batt voltage display on the trip computer - you'll probably need to put the dashboard into self-test mode to get to it though.

[Gooly]

The regulator on my volvo 360 blew once, it was sending 40-60v through the system battery was fine though, didnt change it and it holds charge and all. The car was fine as well, though not much on that car is electric so things might be more complex with an EFI puma with electric gubbins.