Alternator Not Charging Battery - Causes?

K

Kern47

Member
Hello,

A few years ago my alternator died while driving. Got recovered back home where I bought a rebuild kit (new slip rings and a voltage regulator) and also changed the battery.

That seemed to fix it. Although after that, there was occasionally a battery light when first started, and if not blipped to about 2k-ish, the car would start stuttering and die. Lived with that a while until recently I let my battery die completely. Then when jump starting, the battery wouldn't charge. Checked it while engine off and it read 12V, with the engine running it was around 11V (must be alternator again, no?).

Just fitted a new Valeo voltage regulator (as I cheaped out on the first one). Car back together and the same thing. Starts fine, then battery light comes on, won't go off and car starts to die.

My question is, what else is there to go wrong with an alternator? Or is it likely that I made a mistake during my rebuild/soldering of the internals and slip ring? Or perhaps another issue elsewhere?

Z4M, so reluctant to buy a new one, but may have to pay to get it refurbished elsewhere.

Thanks for any input 👍
 
No expert on car electronics but I understood that jump starting was a big no no on these cars due to damage it can cause to some components. However, what about battery, if it's gone flat it will never be the same even when fully charged, may show correct voltage but amps could be down. If battery is old start with a new one but it seems to me you might need to buy a new alternator.
 
Mike6 said:
No expert on car electronics but I understood that jump starting was a big no no on these cars due to damage it can cause to some components. However, what about battery, if it's gone flat it will never be the same even when fully charged, may show correct voltage but amps could be down. If battery is old start with a new one but it seems to me you might need to buy a new alternator.
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Or fit a new diode/brush pack
 
Thanks for the replies.

The brushes come with the voltage regulator so they've been changed. The battery maybe has had a bit of abuse over the winters, so maybe I'll give it a go changing that for what it's worth.
 
Scooba_Steve said:
Mike6 said:
jump starting was a big no no on these cars due to damage it can cause to some components.
Click to expand...
There are jump points under the bonnet, just don't do it at the battery.
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Even using those can kill off the SIM85 on prefacelift cars.
 
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