Quiescent current on '05 GT?

[hal9e3]

I've got a small (~150ma) draw when the car is off that is killing batteries (along with a couple of other goof ups - long story). When I remove FB15, which is for the dome light and several other things, it drops to < 20ma. Is this the normal quiescent current for the car or do I have another leak?

[912]

~150mA is a normal current-draw value for our cars when parked/sitting.

[hal9e3]

Well, I was getting some weird readings so I'm not sure what to think. I put an ammeter in line with the + terminal and when I first hook it up it reads about 500ma. It quickly drops to about 300ma, then about 30s later 160ma, then 80ma, then another 30s later ~17ma. I was able to find two fuses that dropped the current another 1.5/6 ma from there. Not sure what's going on. I didn't find any dome/hatch/door light issues (interestingly enough, the current goes up about 30ma when I open the rear doors (no light) or the hatch (light off). All I know is it killed a battery after two weeks of inactivity. I got a new one and a trickle charger to go with it so I think I'm safe from here on out but I really want to figure this out so I can take the car with me on the road, where I won't always have access to an AC outlet for the charger.

[FAILBOT]

So are you saying that eventually your resting current draw is 17ma? That would be considered normal draw. Anything above say 25ma to maybe even 50ma on the high side would be considered ok. Above that and you have what is called a parasitic draw. You might have a little higher draw at first while computers are going into basically a standby/sleep state which could explain your readings. If they keep going over normal draw while at rest, then you could do some test. While your meter is hooked up and vehicle is off at rest, start pulling fuses until the draw goes away. That will narrow down the circuit section you have a problem with. If there are multiple components on that circuit, then you must plug the fuse back in and start unplugging those individual components until the draw goes away. That will be the component that is causing the issue.

 

Other things to be aware of given what you have said. Your car sat for two weeks before it went dead. That's a decent amount of time for a car to sit and not run to charge it. A newer battery would be fine in that situation but, aged batteries will have more trouble. Also depending on how good of condition your charging system is in and how far of distances you drive will determine if you're fully recharging the battery after it was started. That alone will cause a battery to go dead even if it is new. Every time you run a battery dead it is deep cycling it and that destroys the battery life much quicker. If your car sits for long periods oc time and you don't live in an area that gets extreme cold weather, then maybe get a gel cell battery (deep cycle battery). It will hold a charge longer and stand up to deep cycling. They just don't have the same amount of starting power (cranking amps) as a regular battery. Which is what is needed for cold weather.

[hal9e3]

So, here's the complete story. A couple of months ago I turned on one of the dome lights, forgot, car sat for a couple or weeks, battery's dead dead, got it replaced. Then, at some point after that I bumped the rear hatch light switch to the on position, car sat for about a week, battery dead but recoverable via jump and drive. Then, after another week or so, go to start the car, battery's dead dead AGAIN, had to pay to replace it. At that point I did all the debug detailed in the OP. I just don't see how there could be ANOTHER problem, but there is. Maybe I degraded the previous battery enough with the hatch light that it was susceptible to leakage degradation, but now that I have a new one it will be OK. I'm trying to swap it with my '14 CTS-V wagon so it doesn't have to sit in a hotel parking lot all the time but I have to be able to rely on it to start when I go to work every morning and I can't leave it on a trickle charger like I'm doing now with it sitting in my garage.

[FAILBOT]

If you want to eliminate a dead battery when your vehicle has to sit for extended periods of time, you have a couple options. Either disconnect the battery terminals or get a battery isolation switch installed where you can easily flip the switch and disconnect it from the car. As long as you don't have a car that requires idiot lights to be reset everytime the battery goes dead. This will eliminate even a normal draw from killing a battery over time.

 

When you run a battery dead dead like that, even new, it is very destuctive to its charging capability. Plus how far do you you drive it after its been started? Here is how a charging system works. Battery has enough power to start the car. After the car starts, the alternator takes over. It should have enough power to run all the electronics in the car AND charge the battery back to its full charge if driven/ran for a long enough period of time (short drive/run times actually deplete the battery). So, your alternator MUST be good and you MUST drive long enough or you will get a dead battery regardless of any other electrical issues you may or may not have. So when your charging system works as it should and you still have issues with dead batteries, then you must check the resting current draw of your system. It MUST not be over the recommended 25-50ma range. If it is, it needs addressed to find the problem. If all that is ok and it sits for extended periods of time, it should be disconnected or even normal conditions could still possibly drain it low enough not to start. Without doing the work myself, I can't think of much else to tell you.