Low voltage possible

(The Jag Man) #1

I am running an alternator and a gauge indicating volts and it barely shows 11 volts. I always drive with the headlights on and if I turn them off I will eventually show a positive charge on the gauge. I have manually checked the output of the alternator and the voltage at the battery with the engine running and they were well within specs. I could run a wire from the battery into the cabin while driving to double check the voltage while driving and noticing this low charge condition. Perhaps the gauge is off? I have a brand new battery in the car.



(Ian) #2

I took this vid for oil pressure , but you can see the volt gauge on start up , swings to charge , but after a few miles the needle stays quite still at the bottom of the gauge !
I still have a dynamo , fully rebuilt a few thousand miles ago !

If your battery is new , and the regulator is working as it should , would there be much need for high volts to show on the gauge ?
What you need is a flat battery , start the car with jump leads , then look at the gauge :grinning:

(Phil.Dobson) #3

Should be simple. If you test the voltage at the battery with known good voltmeter you should see circa 12 volts with the engine off. Start the car and the reading should be close to 14.0volts when the engine is a little above idle. That will confirm the alternator is working.

Then repeat at the connections to your voltmeter on the dash.

(peder) #4

Same setup on a G. My voltmeter says 11,5 at idle/700. Does not vary with rpm. On a second G, the reading is 12,5 at idle and the needle moves between 11-13 depending on rpm.