Why no battery light?

[kalpol]

My alternator is only charging at 9 volts (at most) yet the charging light on the dash isn't coming on. It comes on when I start the car, but goes out. Why is that? The alternator failed a while back and the light came on then, and it recently came on when I lost the belt.

[MunichTaxi]

They all come on when starting, then go out.

If you are only gettting 9v at idle, that doesn't sound good.

Have you tested the output at a higher rpm range?

[kalpol]

Originally Posted by MunichTaxi

They all come on when starting, then go out.

If you are only gettting 9v at idle, that doesn't sound good.

Have you tested the output at a higher rpm range?

Yes, what I meant by that was I know the bulb isn't burned out. (However, if I just start the engine and let it idle, it stays on, until I rev the engine a little. Then it goes out).

I haven't tested at higher RPMs but driving at night with the headlamps on drains the battery.

The only thing I can think of is that the alt. is actually charging but there's a fault somewhere either draining off the current or blocking it - maybe a bad ground or something. I will have to test further.

[speace]

My experience in owning cars of that vintage has been that the light stays out if there is even the least bit of charge being produced from the alternator. I would say what you ae experiencing is typical and that you likely just need a new brush pack in the alternator. Of course, you never really know until you've fixed it. It could always be more a more complex problem.

Yeah, that makes the light just about useless!

[kalpol]

Originally Posted by speace

My experience in owning cars of that vintage has been that the light stays out if there is even the least bit of charge being produced from the alternator. I would say what you ae experiencing is typical and that you likely just need a new brush pack in the alternator. Of course, you never really know until you've fixed it. It could always be more a more complex problem.

Yeah, that makes the light just about useless!

Good point...I realized this morning that the alternator in this car is the same as the alternator on my Fiat - 65-amp Bosch. I have a couple of those around with good brushes, I'll just swap and see what happens.

Thanks!