I hooked my voltage gauge up tonight with one wire going to + on the battery and one wire going to - on the battery. My gauge always reads voltage and i understand why but the question is, is that will it run my battery down?

 

i would think so but not enought to drain your car over a short period of time

 

when i did mine on my 80 i wired it to the fuse block to a slot that had power when the key was turned. i wouldnt want it reading at all times. i doubt that the gauge really pulls enough juice to kill the battery over night but u shouldnt wire it the way you did.