I recently installed a CD player in my 1989 G-reg 740 GLE Estate. No amps or anything heavy duty, just a cheapo from Halfords. Everything worked fine...for a day.
Last week, I was heading home and the car died completely in the middle of the road. It wouldn't even turn the fan or play the radio, the battery was completely flat.
I checked the battery on my meter, and it read 9.2 volts. The belts were fine, so I figured it was my alternator (replaced a few months ago from the breakers).
RAC plonked a battery pack on it and followed me home.
On Monday, I put on a new alternator. The battery recharged itself (new a few months ago as well), and the car started. The meter read 10.8 volts on the battery. Turn the car off, 11.3 volts. Hmmm... faulty used alternator.
Yesterday, went back, got another one, put it on - same thing. 10.8 volts on the system when running, 11.3 when turned off.
The guy I got the alternator from swears up and down that the alternators were working when they left his shop, and I've never had bad luck with this guy, he's honest. So the conclusion I've reached is that there is something wrong with the car.
Has anyone heard of this sort of thing before? If I've got a bad earth or something, will that fry the alternator as soon as it's hooked up? Could it just be the regulator? What would make that blow? I've looked at the wiring on the radio, it looks straigthforward and no problems.
Any thoughts?
edit: spelling

 

most of the time the alternater doesnt start charging the battery untill the car is running at 2000+RPM. put your meater on the battery and bring the RPMS up and then see what it says.

 

Thanks, TedH.
I let the car idle while and watched the voltage; it dropped over the space of a minute from 10.88 to 10.85.
Irevved it up to about 2k, and the voltage dropped right away to 10.61, then dropped slowly to 10.58 after about 30 seconds.
It then stalled.
It's not working, is it?
I'm getting a mobile mechanic to come and have a look,maybe he'll have an idea. I'll keep you posted.
Cheers
englishmike

 

Apparently, a wire worked itself loose on the back of the dashboard and prevented everything from working. The loose wire wasn't related to the radio install, it's just one of those things.
Thanks for your help!