I hooked up my autometer volt guage today but i hooked it into my a/c adapter port(forgot it has power all the time) will this drain my battery. the lights on the guage are not on, the guage is just showing my voltage.

 

Normally the car computer and
radio draw less then 100 mA.
This should not drain the battery unless
it is old.
A meter with LCD may draw a few to 20 mA
A meter with LEDs may draw amore like 100 mA.
unless it is powered by internal batteries.
So my guess is if it is COLD and the battery
is WEAK it may take a day or so to kill the
battery.

 

It would probably take a long time to drain your battery, if ever. But still I would go back & rewire the thing correctly

 

I will, but what wire should i hook it into?

 

lol... its DC bud... and no, you shouldn't have a problem

 

The voltmeter is generally connected to a switched 12V source. Considering how volt meters work, it will take a very long time to drain a battery with it hooked up to a constant 12V source. Should be at least a 1M-ohm resistance, so 0.012mA worst case. You can check that by actually measuring the resistance of the meter.

 

Hook it up to a wire that gets power only when the ignition is on. You could go to the back of the radio or the ignition wires under the dash, both pretty easy.

 

I would personally suggest using a radio wire as they are easier to access. You should be able to find the diagram in a chiltons/haynes manual to help you locate the acc wire.