HELP alternator not charging

[AndyCook]

Drove to dentist and noticed voltmeters reading 12.6 and 11.8. - so not charging
Main battery now flat when I restarted.
Drive belt OK and alternator pulley spinning
Any ideas how to fix???

EDIT:
Started it - using override on the cyrix relay and alternator seems to b e charging - phew
Must have been cold temps, it never got above -10 for last 48hrs
Anyone seen this happen to an alternator before!?

 

[Chris]

Andy, common cause is the brushes sticking. Could be frozen up. Perhaps a good warm up with a hair drier and a generous tap with a hammer shaft. Possibly some squirty stuff in there too. If the charge circuitry has failed then you can replace just that bit. I have a spare alternator down here if it helps. Your brother coming up for Christmas?

The brushes only carry a small current, they don't have the whole 80amps or whatever going through them. So any dirt or interference and they pack up. They slide in a little square tube, dirt tends to jam them so that they don't touch the main contacts. Not difficult to strip and clean.

Chris

Edit - looks like you are sorted then

 

[Nuclear Chicken]

Don't forget also that in this seriously cold and prolonged weather, batteries will be struggling to cope and their voltages will be lowere than usual. Several people at work here had starting issues on various small cars, never mind a donkey of a 3.0 diesel or whatever. Several nights/ days of -200 or whatever it is near you will challenge even the best batteries.

 

[Crispin]

bloody 'ell it's cold where you are.

Several nights/ days of -200 or whatever

 

[AndyCook]

cheers for tips guys

am i glad i got and fitted that Cyrix split charge relay! saved me getting a jump start off a noddy car (if possible?) or a wait for AA this morning
flick of a switch from drivers seat and i could start.

it hasnt been warmer than -10 for over 48hrs and was -16 last night, and vehicle outside... my wife has her subaru forester hogging the slightly warmer garage...!

yeah - maybe it was a frozen part - brushes in alternator or batteries not taking charge

alternator is kicking out 13v on idle now and 13.7 to 13.8 on driving at 55mph, with side lights and blower on
i am sure it was over 14v the other day? but guess it was charging the batteries too on my 10mile drive home

three cheers to Cyrix relays!!! a bargain and worth it!

 

[AndyCook]

cheers for offer of alternator Chris

my brother is down in Stoke for a few days, and coming north again after christmas weekend.
so if i still have probs will give you a shout!

may clean my alternator up if i shows signs of still being dodgy, but looks a pig to get to, under the AC compressor