Problem with battery light?

When the light goes out it should mean the battery is being charged. It is not a battery condition indicator. Seing as the car doesn't start, I would suggest you have an alternator fault, and the battery is flat. Mike.

Yes, the alternators dead. Or the drive belt has failed.

Hello again, thanks for the two suggestions.

What is the most likely, alternator belt or the alternator itself. Is there a way to check this, I have a multimeter. Also, is there something that connects the alternator to the battery in one direction, but does not allow the battery to discharge through the alternator in the reverse director, is there some sort of diode there? could that diode be burnt out?

First test is is the alternator belt there, or has it snapped? Visual inspection will suffice for that. At the same time you could try spinning the alternator (with the engine stopped!) to see if the belt has some friction on it.

Charge battery (you'll need to do this anyway). Put in car. Leave bonnet open. Start engine. Look at the alternator - is it going round? If so, the belt will be ok. If it's making squealy noises, might need tightening. Otherwise it's the alternator itself (well, maybe the diode pack or something, but most places just treat them as the one unit).

cheers, clive

(citroen-ax) gurgled happily, sounding much like they were saying :

That's because before, it was a battery problem.

This time, your car hasn't been charging the battery - which is why the charge light was on. The battery is now flat. Charge the battery up, and fix the reason it's not charging.

It may be that the alternator belt's snapped, it may be that the alternator itself has a problem, it may be a connection.

Most likely the alternator. You should be able to check the belt visually yourself, but if it was slipping enough for the alternator not to charge, I would have expected to squeal, especially when the headlamps or rear screen heating was switched on.

I'd suggest you start by charging the battery.

The amps are too high to check the alternator output with a multimeter.

IME there are at least 6 diodes. A failure of 1 or 2 can result in reduced output. No doubt there are others in this n/g that can suggest checks you can make with a multimeter. Mike.

You can't check the charging current with a multimeter, you'd need a clip-on ammeter. But you can check that the voltage across the battery terminals rises to 14V+ while the engine is running, and doesn't drop below 12V when it's not running.

If you are serious about doing some basic maintenance on your car, at least get a Haynes manual. They are not perfect, but would give you a base to start from. You would be able to find out what the voltage of a fully charged battery should be, and what voltage should be present with the engine running for example.

Better still, see if you have a local college that offers short courses in basic maintenance.

Chris