E30 Zone

hiya

I have a problem with my mates 328i - the battery is not charging, and I think there is a drain somewhere too.

I have changed the alternator and its still the same.

the car is a 95 328i cab with lpg.

I also noticed that the odometer and check control panels stay lit when the key is out, and door locked.

Any help is welcome. Car is also overheating, but lets get this sorted first!

Q

Check that the boot/glovebox lights go out when they're shut.

Use a multimeter to check the voltage across the battery; it should be around 14V with the engine running.

there is no lights in the glove or boot

the voltage across the battery was 11v last time I checked (and was going down - not up)

I think first of all I need to get the battery to charge

Is it a known good battery and alternator? Check the engine-to-body earth strap and all earths from battery and alternator are good.

Cables checked and all fine

Disconnect a battery terminal and use a multimeter to measure the drain current; it should only be around 20mA or so maximum with everything switched off.

Significantly more than this indicates a fault somewhere, so you need to then remove various fuses until you isolate which circuit(s) are causing the problem.

It's also worth checking the bootlid latch area for damage and the closing switch - the area around the bootlid latch on my 328i was weak and constantly cracked despite welding so the switch wasn't making full contact. I swapped the switch with a broken one from a mate's M3 and it drained the battery even quicker, even with the bulb removed from the boot. Just one of those silly little niggles.

ok - that might cover the battery drain - but what about the fact its not charging in the first place?

Could be either a duff alternator/rectifier pack, alternator not earthing properly, drive belt not tight enough/slipping, pulley not turning the alternator driveshaft, bad connector in the back of the alternator or a faulty loom leading from it - you could use a multimeter to check the continuity of the leads.