E30 Zone

Hi, My 325i se 1989 ”˜s alternator is not charging the battery, the battery warning light, is not coming on at all even when first Turning on the ignition. I have been told this maybe the reason the battery is not charging as a blown bulb prevents the alternator activating, is that the case? I need to take the dash off anyway to tighten the brass nut to resolve my temperature gauge problem anyway, so hopefully I can resolve two issues in one hit?

Yes the charge bulb in the dash is part of the charging circuit. If it’s blown then the battery will not charge. Also check the earth on the back of the alternator. If that’s broken or loose then you will also get no charge or light on in the dash

are you sure thats right a blown bulb, and the alternator would not charge, seems daft.
I.m gonna check a wiring diagram.

I can,t believe all that current amps produced by the alternator, goes through a little 5 wat bulb.
to check the alternator is charging, quick test is put all electric,s on. rev engine headlights should get brighter.
( heated rear window, blowwer on max. )
or use a multi meter Alternator should be showing 14 volts when charging at battery terminal.

arrisbmw wrote:I can,t believe all that current amps produced by the alternator, goes through a little 5 wat bulb.
to check the alternator is charging, quick test is put all electric,s on. rev engine headlights should get brighter.
( heated rear window, blowwer on max. )
or use a multi meter Alternator should be showing 14 volts when charging at battery terminal.

It doesn’t go through the bulb. But without a pd through the bulb, the alternator doesn’t get activated. Yeah battery only shows it’s charge no additional voltage from the alternator.

kundiboy wrote:Yes the charge bulb in the dash is part of the charging circuit. If it’s blown then the battery will not charge. Also check the earth on the back of the alternator. If that’s broken or loose then you will also get no charge or light on in the dash

Yes on recent inspection the earth does look frayed and the insulation coming off. I have also recently been working in that area.

sounds like you go a bad earth.

don,t agree battery only shows it’s charge no additional voltage from the alternator.
check battery when car not running should be 12.6 v or more, with alternator charging 14 volts. plus
and headlight trick works too, rev it, if Alt good they get brighter.

okeydokey. i got the wrong end of the stick. hope u get it sorted soon

It’s was a corroded earth in the end, bulb was fine, interesting the ”atwo brass nuts”a on the instrument cluster weren’t brass and weren’t loose, so still at a loss as to why temp. Gauge only goes up by a couple of mm. tested both plugs as shown and gauge didn’t move!?