Originally Posted by rustyroger
Get a multimeter and check the voltage across the battery when the engine is running. It should show 13.5 - 15 volts if the alternator is working, a low reading indicates not charging properly, a higher reading indicates overcharging - a faulty regulator.
The defroster coming on sounds like a faulty relay, probably a seperate fault to your charging issues.
Have any warning lights come on? or not come on as in the charge warning light should be lit before the engine starts and go out when it is running.
Hope this helps.
Thanks for the info, you replied while I was writing my last post! No warning lights, charging light is on b4 engine starts and goes out when running.
I guess its pretty clear its a bad alternator then.