T Nation

Any BMW Mechanics Around?

my 2000 740i just got a rebuilt alternator and it is charging really high - 14.6

im planning on selling it soon so i dont want to sink more money into it… is this dangerous? my neighbor said it could start a fire… our smog shop guy says its no big deal but the battery will last less

any help would be great, thanks!

Sounds like the rebuilt alternator came with an unrebuilt voltage regulator. The smog guy is right- it’ll run the battery down faster than normal. It won’t cause a fire though.

Take it back to where you got the alternator and see if you can exchange either the regulator or the whole alternator.

The mechanic did not charge me for the part. he is friends w/ our family mechanic and said that because the battery light did not come off, he was not going to charge for rebuilding the part.

he charged $150 for the labor

he also said that we could take it to the dealer to have them figure out the light, but that he did not see anything pressing that needed to get fixed… your take?

14.6 volts is not high you are fine

normal range for an alt is 13.5-14.5
if it was more like 15-16 volts I would worry but for it being “very high” it is not I would say you are fine

as for the battery light check for any loose connections on cables clean the ground with a wire brush and some simple green

the service lights are reset through a pin in the diagnostic connector located in the engine compartment it is a 20 pin connector that you have to use a scan tool but I am not for sure if the battery light is the same I assume it is. I know that pin 14 on the diag.connector is for the battery.

in short take it in have it cleared

EDIT: the regulators in most all of todays alts.are internal and when they are rebuilt they come with new voltage regulators.
you have to take the back of the alt. off in order to get to it.

it is not a DIY job anymore unless you have a decent amount of electrical exoeriance.

go to bimmerfest.com and go the forums section of your model and post your question. lots of knowledgable guys over there, even some techs on board.