What voltage do you have on the battery while the car sits at idle or like 2500 rpm?

Mine is at 13,5v at idle and 13,7-ish at higher rpm. Is that low or normal?

That is pretty good Matts.

I think down to 12.5 is okay.


Tom
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See no issue there,I always assumed 13.8 was the norm then I see 14.4volts on my spare Hella regulator .

14.4V is optimal. ~13.5V is acceptable. Many or most 914s seem to regulate to that lower voltage; modern cars almost all regulate to the higher voltage.

--DD

Since my alternator is newly rebuilt I expected to see around 14 volts charging, Maybe its the voltage regulator thats a bit old and tired.

Be careful on the voltage regulator. Some the new replacements do NOT fit correctly and seem to fail regularly. The Bosch is pricey but worth it.

I put a new VR and now get 14V at all RPM. You can test the alternator by removing the plug from the alternator and shorting DF to D+. This will cause the alternator to output maximum voltage around 16V.