IXLR8

That is low. My car under those conditions was at 14.2V.

Did you happen to notice the trend? Was the voltage slowly increasing in time.

black ice

I'm telling you, it's not uncommon to have that low of charging voltage. I've had it on my current alternator for a couple of years with no ill effect. My mechanic said it's not unusual.

Now the whole 5V thing - that's not right...

dave

IXLR8

They're not voltages for optimum battery life.

The Toyota would regulate at 14.4V...sixteen years later, the original battery was still in the car when it was sold. I heard it is still starting the car almost twenty years later.

JM993

I agree. Even if the VR or alternator was bad, you wouldn't have swings from 14V to 5V. A good battery would hold out for a while at a higher voltage. Something is probably loose.

Steve Nagata

Remember guys my car is TPC supercharged.... Using an under driven pulley (Similar to an RS pulley). So maybe that accounts for the difference?

The 5V thing I believe was a fault in my "in car" voltmeter gauge.... I see no drops like that on my professional voltermeter/tester.

Steve Nagata

I forgot ot mention that when actually driving on teh road... I believe the voltages are in the low 14s