Hi guys,
I'd really appreciate some quick advice with this, my alternator recently stopped charging so I put it in at my mate's garage and they replaced it with a new Bosch unit (think it was rated at 130A)
When I got it back I noticed the car was mis-firing and also the lights were flickering even whilst driving (it used to do it at idle but stopped as soon as you revved it).
My mate has now replaced the alternator with another new Bosch unit and also fitted a new battery (apparently they need a particular Lead Calcium battery and mine only had a cheapo one fitted).
Despite that the lights are still flickering even when revving the car, the alternator is charging at 14.8V at idle and 15.11V when revving. My mate is at a bit of a loss as he thinks it unlikely that he'd get two faulty alternators in a row!
Any tips on what is the likely problem? The sparky is on holiday but has suggested a possible ECU fault if it is sending the wrong signals for charg e levels but it's flickering several times a second, I'm not sure even a faulty ECU could send such rapid signals?
Any help appreciated!
|
hiya
I don't think the ECU has anything to do with the alternator charge rate - thats regulated buy the difference in the alternator output and the battery voltage.
Sounds like the alternator is overcharging the battery - the voltage is too high - should be more like 14.5v or so - even whilst reving I think
Are you sure you've put the right size of alternator on? Are the grounds good?
James
|
update - sorry voltage is OK. Maybe worth checking battery and alternator cables. Try voltage drop checks on the earths and the positive. Look at:
www.aa1car.com/library/charging_checks.htm
James
|
|
Couple of points to look at here.Firstly,check the small multi-pin connector(2 or 3 pins)on the alternator to make sure the wires are secure and not fractured.Secondly,it is not uncommon on these for the main output (thick)cable to overheat and cause a high resistance in the charging circuit.Best advice is to run a new cable from the main output terminal of the alternator directly to the positive + of the battery.hth
|
That's great advice thanks guys, I'll pass it on to my friend who knows more about the dirty bits than I do.
Particularly pleased to hear that the voltage is ok as my friend thought it seemed too high.
|
Just an update, my mate has taken off all the connectors to the alternator (the guys at MEG all seemed to point to the Multi-plug), cleaned them and put them back on but it has had no effect, he has now decided that he's leaving it well alone until a competent auto-electrician can have a look at it on Tuesday as he doesn't want to take the "replace it and see" approach to fixing it.
Will keep you posted.
|
FIXED! :-)
The auto sparky said the wiring in the car is fine, my mate ordered in a third alternator (Lucas this time, not Bosch) and the car is working better than ever, the lights are totally steady with no flickering at all.
I'm a very, very happy bunny.
|
Can you check the charging voltage with the good alternator, may help some others in the future.
|
|
|
