Join Date: Sep 2004
Location: Medford, County of Jackson, Oregon, USA
Model: None at present
The - lead on your meter can go to the negative post on the battery, but it's not necessary, it can justbe grounded to a convenient screw or bolt. The size of the wires to the voltmeter really don't need to be very large, a volt meter typically draws well less than one thousandth of an amp. With that slightcurrent flow a 22ga. wire will drop the voltage very little more than a 12ga. So you can install it with whatever piece of wire that strikes your fancy. I'd use 18ga. but that's just my way. If you were installing an ammeter then the story would be different as they handle large current flows. As for the change in voltage with the engine off and running it's not a very large change in the reading, it's actually less than a 10% change from a nominal12V at the battery to 14V with the engine running at 4000rpm, so don't expect to see a large change.
The way to use a voltmeter on a vehicle is not so much the absolute voltage shown on the meter. What you are looking for is a change in the normal operation. If it goes lower than normal with the engine off or it is lower or higher than normal with the engine running. You don't know what the actual temperature is on the temperature gauge, you are just looking for abnormal changes there and that's what the voltmeter is for.
None at present
Past 'Wings: GL1100, GL1200, GL1500, GL1800
Current BMW C650GT