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Date Name Message
25/06/2004 10:13:41   paul   Hi guys
My charge light is refusing to go out regardless of engine rpm, and the battery isnt charging. Im getting about 12.75V out of the alternator at idle, does anyone know if this is too low?  
25/06/2004 12:29:32   Senor   Is that at the battery? You should be getting something like 13.5-13.8ish.
Try pulling the positive lead off the battery while the engine's running. If it stops your alty is duff. If it doesn't it could still be duff. Could be the voltage regulator(little box screwed to inner wing attached to alty)  
28/06/2004 17:15:00   Nesnah   EEK ! What a bum steer.
NEVER disconnect the battery when the engine is running or you will morenlikely kill your alternator diodes.
If it wasn't bust before it prolly is now.

Got an old (OK) alternator & regulator if you needem.  
28/06/2004 17:15:02   Nesnah   EEK ! What a bum steer.
NEVER disconnect the battery when the engine is running or you will morenlikely kill your alternator diodes.
If it wasn't bust before it prolly is now.

Got an old (OK) alternator & regulator if you needem.  
29/06/2004 10:28:54   Senor   How? If the only current flowing through the diodes is that that's running the ignition system, unlikely. The diodes in the alternator are pretty big and mounted on a heatsink and should be able to take the current for a short time. If I'm wrong OK. But I've done it before without problems. My message has been up here for 3 days and you're the first to comment on this example of 'quick n dirty' engineering.
I'd be interested to hear anyone else's opinion on the matter, just in case someone really does fry their alternator.  
29/06/2004 12:39:14   Alec   I've done this many times without issue over the years. I wouldn't do it on my modern Viggen though!
 
29/06/2004 16:06:05   Alistair   Agree with Alec, modern cars have more sensitive electronics, but a V4? No worries!  
10/07/2004 11:48:47   paul   thanks for all the advice, i went to a scrapy and found a vauxhall alternator that fitted and seems to work great.
I think you should be fine running the car without the battery on ant car. In any modern alternator the output has already been rectified and smoothed out and regulated to a nice steady 13 and a bit volts. Since this runs in parallel to the battery it shouldnt make any difference to the electronics whether the battery is connected or not, but thats just my opinion dont hold me to it...  
19/07/2004 16:24:05   andy   what type of vauxhall alternator was it . I keep blowing regulators and at 60 quid a pop its pricey , I reckon being able to have a alternator with built in reg should solve it. You try putting in 16+ volts to a battery and watch it boil - Doh  
22/07/2004 18:47:24   paul   it was for an astra, but im not sure what age. I asked to look at astra alternators and they all had the same mountings (you'll need to come up with a new way of mounting the top mount, i found i could do it by bolting together two normal mounts), except on the later ones (they were shiniest) the pulley sat too far forwards to sit in line with the rest of the pullies, so go for an older one. Cost me 25 quid, cheap at half the price!!  


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