Car not charging. Thoughts?
Discussion
Hello all.
My car has been apart for a few months now doing various bits and pieces to it.
I got it all finished yesterday and went out for a drive, then noticed the charge light intermittently coming on and going off. Finally it stayed on and has continued to do so.
I've checked at the battery and directly at the alternator with my meter and am getting around 12.4v so clearly it isn't charging. I have checked the brown/yellow exciter wire and am getting 12v there too. Presumably the 'W' wire on the small spade connection is for the tacho? I've checked battery/alternator connections are secure and clean. Does anyone have any ideas?
My car has been apart for a few months now doing various bits and pieces to it.
I got it all finished yesterday and went out for a drive, then noticed the charge light intermittently coming on and going off. Finally it stayed on and has continued to do so.
I've checked at the battery and directly at the alternator with my meter and am getting around 12.4v so clearly it isn't charging. I have checked the brown/yellow exciter wire and am getting 12v there too. Presumably the 'W' wire on the small spade connection is for the tacho? I've checked battery/alternator connections are secure and clean. Does anyone have any ideas?
Have you checked the 100 amp fuse on the chassis rail near the starter motor, prime candidate they get brittle and crack then eventually break, worth replacing with the midi type of fuse instead.
if output from the alternator is only 12ish volts this would suggest that it's the alternator output at fault as it should be 14.5 volts or thereabouts.
if output from the alternator is only 12ish volts this would suggest that it's the alternator output at fault as it should be 14.5 volts or thereabouts.
If that test was with the engine off, then the 100 amp fuse is probably ok, as you can see the battery from the alternator, which are separated by the 100 amp fuse. But take it out of its holder and make sure it is in one piece, as they can work intermittently across a hairline crack. The fuse is under the chassis, directly below the alternator.
If that test was with the engine running then the fault lies with the alternator or exciter, as it should be producing about 13.7 volts and what you are seeing is the battery voltage.
Last time I got those red light symptoms my alternator was dying.
If that test was with the engine running then the fault lies with the alternator or exciter, as it should be producing about 13.7 volts and what you are seeing is the battery voltage.
Last time I got those red light symptoms my alternator was dying.
Thanks very much for the replies chaps, yes I tested the exciter wire engine off, ignition on and got 12v to it. Funnily enough I have just put the engine back in and put the 100a fuse back into its holder on the RH engine mount bracket. Tightening it down on the connectors could well have caused it to crack or break as you say. Much appreciated. Will check tomorrow when I have my overalls on! I was just determined to rule out everything before I reach into my pocket for a new alternator.
LewG said:
Thanks very much for the replies chaps, yes I tested the exciter wire engine off, ignition on and got 12v to it. Funnily enough I have just put the engine back in and put the 100a fuse back into its holder on the RH engine mount bracket. Tightening it down on the connectors could well have caused it to crack or break as you say. Much appreciated. Will check tomorrow when I have my overalls on! I was just determined to rule out everything before I reach into my pocket for a new alternator.
Don't buy a new alternator, get the old one repaired. If you could get a Magnetti Marelli alternator you would pay a fortune. Chances are you will have to exchange what is a well made alternator (MM) for some cheap crap.I paid around £20 for a repair kit; it is a 10 minute job to change the rectifier and brush box. All done from the outside of the unit.
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