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franken · 05-26-2022, 02:29 AM

The gauge reads a representation of the voltage difference between a spot close to the the battery vs one close to the alternator. If the battery side is higher than the alt side, it shows toward the discharge side. By representation I mean that the gauge is set to read from the center and move left or right depending on which side is more positive. Note that the gauge has no units (other than C and D) and is calibrated not at all.
I'd test by measuring each side to ground with a DVM.
Turn on all electrical items such as lights, heater blower, wiper, dome light, etc. with the engine running and see if the gauge moves.

05-26-2022, 02:29 AM	#3
franken Registered User Join Date: Jun 2013 Location: Somewhere Posts: 3,052	Re: Battery/Amp Gauge The gauge reads a representation of the voltage difference between a spot close to the the battery vs one close to the alternator. If the battery side is higher than the alt side, it shows toward the discharge side. By representation I mean that the gauge is set to read from the center and move left or right depending on which side is more positive. Note that the gauge has no units (other than C and D) and is calibrated not at all. I'd test by measuring each side to ground with a DVM. Turn on all electrical items such as lights, heater blower, wiper, dome light, etc. with the engine running and see if the gauge moves. Last edited by franken; 05-26-2022 at 02:34 AM.