On board volt meter readings

Joined: 10 Jan 2004 Location: Narre Sth. VIC

Has anyone else found that their volt meter in the cabin to be totally incorrect? Mine reads at ~10.5v when the accessories is turned on whilst my multi-meter on the battery reads 13.5v and if i start the engine the inside meter reads from between ~10.5v to ~12.5v and on the battery it reads 16.1v

Does the inside meter measure the voltage from the accessories and not from the battery? Thats the only thing i can think of, hopefully someone can set me straight one way or the other.

BTW i'm pretty sure my multi-meter is working fine, and everything electrical in the car seems to work fine too.

-Miz

Joined: 11 Jan 2004 Location: Adelaide

Miz

I'd say both meters are incorrect. A fully charged 12V lead acid battery should read around 12.6V at rest (although may read higher immediately after coming off charge.) 13.5V doesn't sound right, and 16.1V while charging (at idle?) is quite high. I'd be worried if it was much above 14V (at idle.)

But the readings you are getting inside are too low. At 10.5V a 12V lead acid is all but dead - you'd be lucky to get a glimmer from lights, much less start an engine.

Can you get a third meter?

Cheers,

Scott

Joined: 11 Jan 2004 Location: Adelaide

Sorry Miz, I didn't really help, did I?

The volt meter should be measuring the battery voltage, whether the engine is running or not. If you are concerned about voltage loss somewhere, try measuring voltage in your cigarette lighter socket and compare with what you are measuring on the battery.

Volt meters are generally high impedance devices, drawing very little current. For a wiring error to cause the problem you are seeing you would need a very high impedance connection somewhere. Have you checked the voltage at the back of the meter? I don't know how the connections are made, but a dud contact there would be my number one suspect.

If you can disconnect the meter from the car, try connecting it directly to your battery and see what it reads there. There is the possibility that your meter is just stuffed!

Let us know what you find,

Scott

Joined: 10 Jan 2004 Location: Narre Sth. VIC

Thanks Scott, i'll try the cigarette/aux outlets tonight. It doesn't worry me that the gauge may not be working correctly, my wife was concerned that she may end up with a flat battery thats all.

-Miz