The battery on my H3 always dies.
I will leave it in the garage for a week and it is dead.
I have replaced the battery twice.

If I dont use it every day then I run the risk of getting stranded. It is embarrassing now to always ask people for a "jump" and annoying that I need to put it on a battery charger.

Just because it turns on in my garage doesnt mean it will turn on again 8 hours later if I do not drive it much.

So I am sure I have a drain somewhere on the system.

Is this something I can troubleshoot myself?
Is there a common known problem of what is sucking up the battery that I can look into?

I can take it to a mechanic if you tell me to but I want to hear from what people on here say.

Any help, suggestions, etc. is appreciated. It is a 2010 H3. Thanks

 

The Hummer H3 draws about .100mA of current even when it's not running. You should verify that all your ground are solid and that you have replaced the crappy OEM battery terminals with good aftermarket ones. This will ensure your H3 is charging properly when it is running.
About a year ago I invested in a small battery jump box that works fine and ensures I never get stranded. It's about 8" x 4" and fits in my seat back. It works on the 5cyl but probably won't turn over the V8. I picked it up on WOOT for about $54.




You can also add a cut out switch to the positive battery cable and disable it when you know you are going to let it sit for long periods of time.

 

Thanks. I will check the current later today. So 0.100mA? So you mean only 0.0001 A? wow that is a very tiny draw. Just want to confirm .. I may need to buy a more sensitive ammeter .. but that number is helpful because i will know in 2 seconds if I have a real problem or not and can probably trace each fuse to find the general vicinity of the culprit.

 

I'm currently experiencing the same issue in a 2010 H3T. If it sits for more than 5 days, the battery is low enough where it won't turn over. I investigated this a little bit, but I have not gotten too far into it. I will in the near future. I've heard the radio and/or onstar module can continue to draw on the battery after the key is out. I replaced the original battery with an ultima, and it still drains it enough to not start.

 

drain is 114 ma or .114 amp. thats 1/10 amp, quite a bit . over 4-5 days mine gets lazy. i have 2 batts. the spare is isolated. i can jump with a short wire.

when you check,it will be 2 amps till things settle down, about 1 min or less. then 114 ma. yours may vary .it may actually have a bad leakage. check with ammer in one cable.

mine is 2010 adventure

 

Under the cloth covering of the positive battery cable is the o star fuse about 6-8 inches from battery clamp.

 

Thanks for all the help guys. So I bought a sensitive ammeter.. I think the correct way is to test each wire separate? when i put them together i would get random numbers.
I disconnected the onstar fuse.. that skinny wire was maybe pulling 60ma at most.. then the other two fat wires are combined maybe pulling 110-130ma. So I dont think I have any unusual battery drain.

How long should this car battery last without needing a charge? I mean I have owned this for 7 years and this has never been a question (i do not drive it much -- this is not my primary driver.. so i have gone months before without using it. it has maybe 18K miles in 7 years to give you an idea).

I am debating whether to put in a trickle charger now.
I have attached a battery charger to it now and it is pulling 12A charging. I'll let that run for a bit and get the voltage up. Anyone dig into voltage drops on the H3 over time? What should the voltage be with the battery hooked up fully charged and what should it be after a week or something like that? I have an optima red battery in it.. I figured that would be the best thing for a car draining its battery but I am not an expert, let me know if that was a mistake.

Thanks for the help... the good news is I didnt have to spend an hour troubleshooting.. and thanks for the tidbit on the onstar fuse, i never would have found that thing if i didnt know it was there.

 

I installed an 'onboard' charger from Harbor Freight. If I know I won't be using my 3 for a few days I just plug it in.
https://www.harborfreight.com/15-amp...ner-99857.html

 

a week will pull down my 7 yr old batt. gotta run it 3 days for a while.10 minutes wont do it.
trickle charge a good idea.

 

Mine sits 10 days-2 weeks at a time in the summer when the weather allows bikes and other cars to be driven, it starts fine. I once let it sit for 22 days, and it needed a charge before it would fire up.