Tim Emsky

I am experiencing intermittent voltage fluctuations where the guage and voltmeter readings JUMP from the normal 14V to 16V or 16.5V. This is occassional, and apparently not connected to any other conditions with the car during these "incidents". I am presuming that it is simply a quirky voltage regulator. Turning on ALL accessories; lights, blower, rear defroster, etc. will lower the voltage somewhat, to approx. 15.8V
Am I missing anything here? Are there other conditions besides the voltage regulator that can cause a spike in alternator output voltage?
Are aftermarket voltage regulators available for the Bosch Alternator?
This is on my '88 S4 Auto.
Thanks in advance.
Tim

IcemanG17

The gauge is somewhat accurate......mine consistantly reads lower than it really is...maybe your is the opposite....or the regulator is going bad?

the flyin' scotsman

Are you measuring these voltage spikes? If so where?

Where in BC are you?

Fabio421

Does your AC fan blow harder or your lights get brighter when this spike happens?

Tim Emsky

The alternator voltage on the guage and also confirmed by a voltmeter will occassionally "spike" to approx. 16.5 to 16.7 Volts. It doesn't appear to be triggered by anything; just comes and goes on its own. Not affected much by rpm.

Tim Emsky

Yes, the accessories "speed up", which causes huge concern about burning up electronics due to excessive voltage.
I'm in Prince George; frozen north.

the flyin' scotsman

PG is a little far away for a personal visit.

If your confident that the 'spikes' are confirmed then the regulator is gone........a new/rebuilt alternator is in your near future.

Tim Emsky

Malcolm, are you aware of any sources for just the regulator? It should be a common Bosch part.

Fabio421

Not necessarily. Mine has done this for about two years with no ill effects.

V2Rocket

You could hook up some 12" subs without an amp!

Mike Murphy

I would change the regular as soon as possible. Your electric motors on the car might survive, but the computer and other electronic components can be sensitive to these spikes.