Crazy Full Beam Problem

[Extremepower3918]

I was driving along at about 60 with my dipped beam on, I then switched to full beam and the whole electrical system cut out for about half a second, the engine lost power and the radio turned off. Then the car continued as if nothing had happened. This happened 4 or 5 times and when I tried it at idle when I got home the engine stalled and cut out completely.

I've tested the battery, its not the best but it had 13.8V when running with the lights on and the car cranks well. I also tried driving it again and it seamed to fix itself for a while and only cut out occasionally.

I think it's also a bit down on power at the moment but I'm not sure if that's related.

I'm going to try a different battery tomorrow and see if that helps. Has anyone had a similar issue or got any ideas for what it might be?

The car is a 316i touring.

Thanks Rob

[boiliebasher]

I'm not great with electrics but sounds like a weak battery to me.

[Extremepower3918]

I think it might have been the chinese battery isolator that I got off ebay which was causing a bad earth. I've removed it now so I'll see if that fixes it.

[Contours]

Think it may be more alternator related as this is responsible for keeping the electrical system in tune while the car is running. Switching off the radio and full beams and unnecessary electrical loads is done automatically when your voltage supply is low. Maybe your alternator brushes are wearing down or the battery is only being charged intermittently.

[Extremepower3918]

Thanks for the reply. It hasn't happened again since I removed the battery isolator but I'll check the alternator if I have any more problems.