Generator light remains on

[welshdragon]

Hi I have an issue on my 77 911 2.7
With the generator light remaining on
I have had my alternator refurbished so don’t believe that’s the issue
I have also changed the original voltage regulator because that didn’t show any charge at the battery when testing it with a voltage meter it only give the battery output at a constant 13v
I have also tried 2 new replacement Voltage Regulators and both of those give a battery output reading between 14.7 to over 17 when the engine is revved and the battery fluid is coming from the overflow tube
The battery is receiving to high a charge now so I assume the alternator is working
Any advice from you kind US people would be greatfully appreciated
Cheers

[spoke]

There are 3 spades on the VR, DF, D+, and D- just like the 914. Here's the 914 charging system schematic. The 914 system is similar to the 911 although I believe the 911 alternator has more diodes than the 914 alternator.

Check all 3 voltages at the VR with respect to chassis ground, not the engine case.

D- should be zero volts.
DF will bounce around 5-10V depending on level of charging.
D+ should be equal to the battery voltage.

Measure battery voltage on the POS terminal to chassis ground.

D+ and the battery POS should be equal in voltage. If unequal, then it points to an issue in the alternator.