306 alternator problem?

How can I check whether the alternator is working ok?
Pulled up outside the garage after a 12mile journey turned off engine , opened garage door, engine wouldn't restart - seemed to be low batt
volts (dash lights all dimmed). Had battery on charge overnight, started immediately this evening.
The battery is 2 year old (and was changed because of similar symptoms of not holding a charge).
If it is the alternator at fault is it a garage job or can it be changed at home? Any websites or info you could point me too?
Also are the diodes housed within it or separately? thanks
Geoff
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If you have a volt meter, stick it to the battery terminals, it should read 12 volts, then start the car and the voltage should rise to about 14.2 volts.
Any increase from 12 volts while the engine is running means that it is charging, the larger the charge the better, up to a limit !! If the voltage goes up too far, then yer battery is cookin.
Hope that helps for now, but I am sure that someone will be along with a much better explanation soon.
Regards Slim
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Tnx slim
with just headlights on it reads 12.1V with engine running and headlights on it rises to 12.6 so it appears to be charging by only a small amount - though with a freshly charged battery would the charge current be small anyway? The fact it doesn't get near the 14.2 bothers me - should it?
Geoff

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Geoff.
Even with a fully charged battery, you should be getting somewhere near the 14.2 mark.
I would guess that the alternator has shit itself and needs replacing.
Regards Slim.
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It does sound as if the alternator is not working properly. How old is the car etc? Which engine, and does it have air con? All this only affects the complexity of removing and replacing the alternator. Not a really difficult job, depending on access. Most battery suppliers will do a check on the charging system for you. Did this battery have more than a 2 year guarantee, if so the supplier would probably check it out for nothing, just to avoid having to replace it under the guarantee.
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wrote:
Is 12year old, 1600 petrol, no Aircon
Had the battery checked at garage (quote for new alternator was around 100+ mark. Considering the age of the vehicle - is probably only worth couple of hundred quid? but battery was ok, rechecked voltages on getting home, now there is no increase in volts when I rev the engine. Someone did suggest it may be brushes? problem now is getting the b*gger out.
have slackened off the adjusting screw which seems to have made no difference to the belt tension and also removed long bolt from top. Struggling now to even see let alone reach the lower bolt - guess its really a job for a ramp? and not yer casual diyer (bodger) scrabbling around on the garage floor.
rgds
Geoff

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Hi Geoff.
Recently I experienced the similar problem and guess you'd want to hear about it. The symptoms were at first intermittent charging, then no charging at all. The charging indicator went off and it was obvious from the intensity of various lightbulbs around the car that the alternator was not producing current. The car is 15 years old 309. At first I wanted to try to fix it by myself, but then I learned that there are a great numbers of different alternators fitted to the same car model so it's best to leave the job to the specialized car electrician. They usually have replacement parts for most popular models and sometimes these are interchangable. I also found out that I have Bosch alternator.
Anyway, the guy at the garage quickly dismounted the alternator (from under the car!) and determined that regulator was faulty and need to be replaced. Brushes are being replaced together with the regulator and with the car of that age it's good to check the wires and contacts around the alternators as well. The bill was around 20 for regulator and about an hour of labor cost.
Hope that helps Mislav
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On Tue, 9 May 2006 10:17:54 +0200, "mislav"
Thanks Mislav
Strange thing was the charge light never did indicate a problem (the bulb was ok btw) anyway I finally got it removed and found a replacement at a local auto salvage yard for just under 30. Replaced it tonight and now seeing 14V across the battery, so think problem sorted. It was satisfying to have repaired it myself, and I could do another in shorter time, but maybe will leave things to a garage next time.
cheers
Geoff

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Slim wrote:

Before you replace anything, remove both battery terminals, clean them, tighten back on well and then re-check.
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and check the minus side connection to the chassis.
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