What would cause the battery to stop charging?
Discussion
Did a head gasket job on a car, all seemed ok, ran for abotu 20 miles.
Left it a couple of days, then came back to it. Had all the lights on as i was trying to get to the bottom of a light bulb fault. After 15 minutes the batter was totally flat.
Borrowed a battery charger and charged it all night. Took it to the local auto shop who tested the battery and all seemed fine, he said the battery was a little weak but was being charged by the alternator, and it had the required power to start, even if at times it was a little sluggish.
Drove it again the next day, battery light was flickering under accleration, then after a few more miles the light came on and didnt go off.
Turned the car off, battery now flat as a pancake and wont start. The manual says the warning light means the alternator isnt charging the battery.
Could the alternator have just packed up? Or could it be the battery not holding a charge that might bring that light on? I've checked the wiring and cant see anything split or unconnected.
The other option is to take the battery off my other car and see if it charges that, but its a pain in the arse to swap them over and i dont want two dead batteries and two dead cars.
Left it a couple of days, then came back to it. Had all the lights on as i was trying to get to the bottom of a light bulb fault. After 15 minutes the batter was totally flat.
Borrowed a battery charger and charged it all night. Took it to the local auto shop who tested the battery and all seemed fine, he said the battery was a little weak but was being charged by the alternator, and it had the required power to start, even if at times it was a little sluggish.
Drove it again the next day, battery light was flickering under accleration, then after a few more miles the light came on and didnt go off.
Turned the car off, battery now flat as a pancake and wont start. The manual says the warning light means the alternator isnt charging the battery.
Could the alternator have just packed up? Or could it be the battery not holding a charge that might bring that light on? I've checked the wiring and cant see anything split or unconnected.
The other option is to take the battery off my other car and see if it charges that, but its a pain in the arse to swap them over and i dont want two dead batteries and two dead cars.
Well either the battery isn't connected to the alternator, the alternator is broken, or the battery is broken. The battery is connected to the alternator via the wiring loom for the positive and via the earth strap (and engine block) for the negative. So given the work you've been doing, I'd say the earth strap probably isn't connecting to the engine properly.
Image taken from another site, however the black plastic block on mine, is cracked. Part of the metal seems to have snapped, its the part which goes into the black plastic block. It's still attached but the sealed plastic block is crumbling a little, it appears that the bracket part has bent back and snapped a little at the joint with the plastic. Im unsure what this little block does, but am guessing this could be the problem.
Acheron said:
Took it to the local auto shop who tested the battery and all seemed fine, he said the battery was a little weak but was being charged by the alternator, and it had the required power to start, even if at times it was a little sluggish.
Knackered battery is by far the most likely explanation IMO.What test did they do?
Is the battery more than 2 years old?
Acheron said:
Image taken from another site, however the black plastic block on mine, is cracked. Part of the metal seems to have snapped, its the part which goes into the black plastic block. It's still attached but the sealed plastic block is crumbling a little, it appears that the bracket part has bent back and snapped a little at the joint with the plastic. Im unsure what this little block does, but am guessing this could be the problem.
I wouldn't have thought so, that's a relay for something close by probably.can you jump start the car? if so get it started then stick a multimeter across the terminals. i'f you're reading less than 13v odd then it would suggest the alternator or wiring is faulty. it should still hold the same output with all electrics - heater blower, headlights etc. on.
i've managed to kill an couple alternators in the past when doing an engine swap, they seem to be quite fragile. as said though, check the earth, and that you've wired it up correctly!
i've managed to kill an couple alternators in the past when doing an engine swap, they seem to be quite fragile. as said though, check the earth, and that you've wired it up correctly!
Acheron said:
E30M3SE said:
Check your engine earth as a first step.
ETA; or the earth strap on the back of the alternator if yours has one.
Ahha! I was hoping someone might say this, as i had some confusion with it when re-aplying it. What could have gone wrong with it. Not correctly earthing?ETA; or the earth strap on the back of the alternator if yours has one.
If the earthing looks OK get a mutimeter set to 12VDC and connect to the back of the alternator, red to the + black to the earth and measure the alternator output, at idle, anything less than 13Vand you have issues with the alternator charging, at a fast idle (2.5K RPM's) you should be getting 14.xV
What car is it?
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