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My battery warning light came one yesterday.

When i got home i checked the battery. Car off, the voltage was 11.3v.
Fired it up and the alternator was working very slowly and took it up to 11.8v after 2-3mins. It then stopped going up though.

Turned on all the electrical goodies and it started to fall quite rapidly like the alternator couldnt keep up.

When the car is reved theres a slight humming/buzzing electrical noise which seems to be coming from the alternator.

If the battery is dead would there be any way that it could prevent the alternator charging it past a certain point? Or is it certainly a f****d alternator?

One last very wierd thing, i turned the car OFF and noticed a very quiet humming noise from the engine bay?!?! Like a high pitched electrical squeal although very very quiet. Seemed to be from the alternator. Pulled the two pin connector off and it was still there?
Came outside 20mins later and it was still making the noise , i disconnected the battery and it stopped so i left it off over night for piece of mind.

What would you guys do?
Put a trickle charger on the battery out of the car and see if it takes charge? To Rule that out?

Would it be worth cleaning the bushes and rings on the alternator or is it time for a new 1?

Any help would be great as im a bit f****d without my car
Thanks
Nick

Your alternator is dead. That's what's whining when the engine is off, its draining your battery.

Cheers for your help. Your right about it draining the battery slowly.
Pulled the alternator off this morning, is there anyway to get it repaired
or do i just have to bite the bullet and buy a new one? The end has about 2-3mm
of play at the shaft is this normal?

£280 for a new genuine replacement!
Cheers

Nope that's not normal. Go to any decent motor factor for a replacement. Expect to pay 75 to 125 plus your old one in exchange.

i second this, a healthy alternator will put out around 13.8volts give or take =)