Quick Question...Battery Light on

[WADE30]

I am still kind of new to E30's and want to make sure my assumption is correct. Tried searching but found nothing to the point.

89 E30 M50

I rebuilt the engine completely, and changed almost all parts except the alternator, I got it tested back in October of 08 and it tested fine.

But a couple weeks ago the battery light would come on dimly then shut off. Now it still does that but also sometimes comes on at full brightness, and it might be coincidental but it seems when I am pushing it, it comes bright.

Battery is brand new basically. So does this Battery light warning mean alternator not holding charges so well anymore?


Thanks!!

Wade

[7pilot]

Bad alternator...likely worn voltage regulator brushes.
or
Bad new battery.

Try adding another ground from the alternator case to the engine block.
Do you have the block and the head grounded to the chassis?

m

[WADE30]

Just checked the the voltage flow on the battery when the engine is on. It is about 12.75-12.89 V while on.

[Adrian_Visser]

time for a new alternator

[WADE30]

OK so I got a new alternator. The car wouldnt start. The battery was dead so I had it charge tested and the batter holds a charge fine.

Which means something is not working in which the battery doesn't charge.

I was thinking voltage regulator but isnt that built into the alternator, and by mine being brand new that would mean it's fine?

Anyone?! Help! I have to get back home to Phoenix for school.

Edit: BTW I know it doesnt charge the battery because after I jump started the car with my mom's van I drove the car for an hour in hopes to charge the battery...shut it off for a minute...dead.

[Wh33lhop]

Hm. What kind of alternator did you get? Autozone or something? I've heard of plenty of Autozone rebuilt axles and starters being bad, I wouldn't be surprised if an alternator was too, although I haven't specifically heard of the problem. Get the alternator tested if you can.

[Bmjpv]

Testing

Charge the battery to get it to 12.5v (standard) AND at that time check the alternator for correct output . You can will not know the correct answers without a voltmeter. Good luck , Joe

[WADE30]

It's from Napa. Bosch rebuilt 80 Amp. Alternator works fine and so does the battery. Any other suggestions?

[MattM]

so you ran the engine again after charging the battery with the new alternator, and got ~13.5v on the battery, but the light is still comming on? im confused

who did the engine swap? maybe something in the C101 isnt connected correctly.

e34 harness alternator output is pin 25 on the x20(blue wire), i believe the e36 is different.