battery light is on but alternator tested fine,,

[dmc2884]

i had my alternator tested and it showed that it was charging fine, what could be the problem?

[Vee]

Possibly belt slipping ?

[sniff diesel]

Vee said:

Possibly belt slipping ?

Would be squealing like hell and it wouldn't show up as charging if that was the case. Could be a duff battery?

[dmc2884]

The car has been starting fine for 2 weeks with the battery light on.

[Neil.D]

Have you tested the voltage of the battery?

Go to Halfords - shiet I know - but they will test it for free if you dont own a voltameter.

[Apache]

Neil.D said:

Have you tested the voltage of the battery?

Go to Halfords - shiet I know - but they will test it for free if you dont own a voltameter.

Make sure they check it properly, ie with a shunt to check the current not a voltmeter

[BMW-SPORT]

A good way to see if the battery has died is to turn on the lights and heated rear windscreen and blower, then try and start it, if it really struggles and the lights go way dim then the battery is probably dying.

Make sure the monkeys that test your battery open the boot and vent it for a few minutes first or the hydrogen that has likely built up will cause the battery to blow up if they cause a spark with their leads.

[roofer]

What BMW?

Does the light glow brighter when revved? = Rectifier
Does it glow dim when revved? = Brushpack

Or does the light just stay a constant brightness? Could be ignition switch/relay/fuse.