Key-off drain


Is it possible to have a slow or a fast key-off drain?

My mechanic said he measured for a key-off drain on Tuesday and found no electrical drain. I drove the car home. The car sat in the driveway and was not driven for three days. When I went to start the car, it was dead.

Is it possible that the car had a slow drain that he didn’t detect? Or, is it necessarily an “intermittent” key-off drain?

Thanks in advance for any ideas.




What’s a key off drain and what can be done about it. It often takes me several tries to get my Subaru started.


Once you get your car started & the battery charged up, park the car in a dark place. Then look at in the dark. You may find that your trunk or hood light is on. It could be that some dumb light inside the car is on. (glove box)
Do you have satellite radio or an after market radio? check that, too.


ALL modern cars have some amount of battery drain, even when the key is off. The radio constantly draws current to maintain station memory, the vehicle’s computer(s) constantly draw current, as does the security system (if so equipped).

It’s not a huge draw, but it IS constant.


A battery in good condition should not be adversely affected by these small drains. How old is your battery?


I go with what CNCOP said. I had the same problem with a '92 Olds Ciera. The switch controlling the glove box light was misadjusted causing the glove box light to stay on all of the time. Re-adjusted the push button type switch, re-charged the battery,–end of challenge. Trunk or rear hatch lights should be checked, also. If you have an under hood light, check that also. Park in a dark area, shut everything down, and check for a light that stays on.