Is the alternator going bad?

[95BMWIC]

I took a trip to Minnesota with wife - 4 hours away and decided to take the e30.. yeah I married well...

Anyway - we get back from shopping and I popped the hood (engine running) to check vacuum, oil, and fluids and my voltmeter was pegged at 16-17 volts ( I have a gauge wired into the ignition coil to monitor the volts) I was a bit surprised as you know that is too high.. the car was warmed and the ambient temp was 34 degrees or so.. It was late - so I shut down the car and we went to bed.

This morning - I get up and go out to check everything (I brought tools and have my handheld volt checker) and everything is fine this morning - 13-14.5 volts to battery. Battery has no sign of damage. I have an interstate in which you can pop the tops off - but not sign of boiling or leaking..

I read on pelican forums if the regulator is broke - then you can get that kind of volts.. but I'm trying to reconcile what happened last night. My experience with alternators is that they are either good or bad - might this be a sign of one going bad? (at least the regulator..)


Should I but an alternator just in case - throw it in trunk?

Also - how long can a system overcharge until the battery gives out or explodes.. Does a guy have a few hours?

[mmark.]

The auto parts stores will want the core, so just remove it and install the new one.
You feeling' lucky?


m

[95BMWIC]

Good point - but they are easy to change. I think I have a 90 Amp.. but how do you verify?

[Kershaw]

I would not run that. An bad alternator will quickly leave you stranded. If it's fairly new, you can try replacing just the voltage regulator itself. If it's more than 4 years old, why bother? Just replace the whole unit.