tonedef 9 Posted October 24, 2007 For ages now my alternator has not started charging until the engine revs go over 3,000. Pretty simple problem I thought, either the blue wire has no supply or the voltage reg is goosed. I checked the blue wire and found 12 volts so ordered a reg which I fitted this morning, start it up and I still have the same problem! Anyone had similar? Quote Share this post Link to post Share on other sites
Crasher 3 Posted October 24, 2007 Are you judging this from a volt meter and does the charging light work? Quote Share this post Link to post Share on other sites
tonedef 9 Posted October 24, 2007 Are you judging this from a volt meter and does the charging light work? I'm using a calibrated multimeter and could quote accurate figures too if you like! But seriously, yes the light works fine and I know it's not charging until I rev the motor, numbers in the region of: 12.8 volts everything off, 12.2 volts after it's started and 13.4 once the revs have gone over 3000 then everything's fine even at idle with lights and a/c etc switched on. Quote Share this post Link to post Share on other sites
Supercharged 2 Posted October 24, 2007 Worth popping to Halfords and getting them to put the Bosch tester on the battery and then test the car Quote Share this post Link to post Share on other sites
tonedef 9 Posted October 24, 2007 Worth popping to Halfords and getting them to put the Bosch tester on the battery and then test the car Oh yes, and the battery is about three weeks old, damn forgot that bit, my dad picked it up for me while I was still away in Saudi, and it was £93 from Halfords! It's been like this for ages, could be a couple of years as I had it off the road last winter but for all that time it's been fine as long as you remember to start it charging by reving it (as soon as it's warm obviously). I'd finally decided to do something about fixing it and it turns out to be not as simple as it originally seemed. Quote Share this post Link to post Share on other sites
yalan 0 Posted October 24, 2007 Yup - had exactly this problem on my last Audi. Eventually thought I'd better do something about it so - Had the regulator replaced by a garage at a service and on the way home, lost all charging power! On the way home the battery finally lost all juice on the M25 and had to call the RAC to put the old regulator back on to get some power. He wasn't a happy man! Sadly it was the alternator. Bought a bosch re-con unit from CAF and all was perfect subsequently. Re-con alt was only about £70 so well worth it. Quote Share this post Link to post Share on other sites
tonedef 9 Posted October 24, 2007 I'm thinking that'll be the answer too, shame I tried to be clever and just swap the reg, means I have a spare one for the new alternator I guess! Quote Share this post Link to post Share on other sites
dr_mat 0 Posted October 25, 2007 It could also be the belt slipping, make sure it's in good condition and correctly tensioned. Quote Share this post Link to post Share on other sites
tonedef 9 Posted October 25, 2007 That's a thought, I'll check the clearance in the tensionner although it does drive the a/c compressor OK so I'd imagine it's fine? It's out for the day now so I'll have to check tonight. Quote Share this post Link to post Share on other sites
davidwort 0 Posted October 25, 2007 Sounds to me like one or more of the rectifier diodes are dodgy, not really fixable as they are soldered to a plate that is in turn soldered to the outer windings of the alternator. Quote Share this post Link to post Share on other sites
Supercharged 2 Posted April 6, 2008 tonedef, did you get anywhere with this? Quote Share this post Link to post Share on other sites
