25-40Mah is about average draw when everything is asleep w/ no aftermarket accessories.

From my personal experience and past issues resolved on the forums, most of the time fast draining battery is from some electrical device installed recently incorrectly or faulty. Have you done anything to your rig in the last three months?

The other good portions of dead batteries and actually from having a junk battery. Do not rely on a single place to test your battery. Could have untrained employees not knowing how to properly work the equipment, equipment is faulty, or an employee tells you your battery is **** to sell you a new one, pay the core charge himself and sell or keep your good battery. This does happen... Battery test doesn't cost you anything, take it to two shops so your 100% posetive.

Very rarely does anyone come up w/ a factory stock component actually causing the drain. The onstar module doesn't generate enough of a current to kill batteries like this. If your not using it, not going to hurt anything by pulling the plug on it- but it wont give any significant amount of reserve back.

If your not using the parasitic load tester, you need to make sure to securly attach your test leads to the battery and to the truck feed. All the power going to the truck will flow through your meter. If you break the connection, you need to start all over again and wait 15 minutes. You almost need an autoranging meter as your going to be registering 600-300Mah when the vehicle is awake, then should drop down to less than 100 after sleep. If you turn the range dial, your most likely going to break the connection and have to start all over again. If you start your meter on the low range to read the difference on individual curcuits, you might smoke it as soon as you hook it up. DO NOT EVER START THE TRUCK LIKE THIS THROUGH THE METER!

Write down the reading after 15 minutes. As you pull each fuse, you should write down to new reading and note which fuse it is- dont worry right now about what it actually is, just write down the name. The difference between the two readings is how much that circuit is pulling.

I always start in the engine compartment and work my way back. Look for any aftermarket accessories. Alot of times they are wired straight to one of the non-fused power taps. Alot of the aftermarket decks require their own power feed now, stereo amp, HID headlights, offroad lights, alarm or remote start, etc... You could pull fuses all day and never be eliminating those circuits. One of the times I had drain didn't show up for almost 3 months just because I was driving the truck multiple times during the day. Never sat for longer than 8-12 hours. My Starr HID headlights were actually wired wrong at the factory. Completely functional, but one or two of the relays were constantly powered causing the drain. So look for anything like that first and disconnect it.

I'd start yanking the fuses in the engine bay first then work my way back. Pull the fuse, write down the reading, put it back. Check the reading- It should be right back at the first reading you wrote down. If its substantually higher some module woke up. Give it 10-15 minutes to go back asleep then move on to the next.

The difference sum of all individually pulled fuses should equal the total draw. If your substantually off, your missing a circuit or somethings wired in your not seeing. Your not going to smoke through this in 20 minutes. Probably going to take couple hours waiting for **** to go back to sleep.

If I lost you anywhere above, let me know.

 

bflorin,

I followed your instruction and after 30min of key off, current amp came down to around 25 mah even with Onstar fuse back on. Then why my battery got drained over the weekend? My 3rd party addition to the circuit is USAspec iPod interface only.

I found when I disconnected the cable connecting between interface box and radio, then current dropped about 50 may last time checked.

I guess it might draw some extra current after key off on some occasion or keeps radio module awake? I don't know.

How do I prevent this happening? I guess when I let the H2 sit more than a day, disconnect the interface box, maybe?

 

your in spec...seriously I'd have the battery checked at a couple different places. You still have the stock battery in there? Whats the rating on the battery? just in case someone before you put an undersized one it. One or two bad cells in a battery could still test good, but do some really wierd ****. I had that happen to. I could drive to the store, come out 10 minutes later to a click...no start. Just touch the jumper cables and it would fire right up. Then I could go for weeks w/ out a problem and it would be back again. Thats what got me to the point of multiple different places testing your battery. Autozone kept telling me it was good. Think it was carquest that tested it as bad.

 

My battery is 2010 Autocraft Gold battery. I had Autozone and other shops to checked out last year but no issue was found. However I had complete draining more than a few times since last summer, it maybe good idea to replace.

When I tested key off current according to bflorin's suggestion when the battery was in normal condition, the current was 25 mah. But the current I tested after the draining was 400 mah. INFO fuse was using almost 200 mah. Does this mean draining occurred when H2 did not go into sleep mode completely?

I was told my USAspec ipod interface continues charging iPod after key off for sometime like 30-60 min. I don't know if this bothers some module going into compete sleep mode.

I will disconnect USAspec cable when I park more than a day to see if the situation continues or not.

 

So ok in march we bought a brand new battery for our 2003 H2 Hummer and in June or July started having problems with the battery again, I mean doornail dead and wouldn't charge up at all on fast charge, it would charge up enough to start overnight on trickle of maintainer setting but next day would die again and this is a heavy duty battery less then six months old, so tonight my wife went out to run to the quickie mart, theast time the Hummer was driven was around 5:00 pm October 9th, tonight is October 10th 11:40 pm and it turned over and then click click click and wouldn't start so I put the charger on it which again usually takes hours on slow charge to get enough charge to start it, so while I waited I did a search which led to a link in this board which had a link to this subject and as I read through I looked at the fuse panel picture link of the engine compartment fuse box and located and pulled the corresponding fuse, at this time the battery charger had been on less then ten or fifteen minutes, I open the drivers door, hit the interior lights override button and pulled a small USB charger from the auxiliary 12 volt dash panel plug that had a small green led on it and put in the key and it cranked right up, it didn't drag and turn over slowly and then start up like a weak battery normally does but instead started strong on the first turnover, and again it hadnt been on the fast charge setting long enough to fully charge it to full charge setting and yet the hummer cranked like it was a brand new fully charged battery so damn onstar crap does more then just drain the battery, it does something much worse because there's no way having the charger on for that short amount of time would have given it a full strong starting charge so it took a few seconds to remove that damn onstar fuse and my hummer cranked like it had a fully charged brand new battery... I'll let you know if I have anymore problems I'll post on it but just from what I've experienced tonight by pulling the onstar fuse I'm suspecting it was the cause of going through two batteries in 5 or 6 months..... Original battery went bad in late march and was replaced and then I had to replace it in June or July and almost replaced the new replacement battery in my hummer now, so I'm on my third battery, because original battery was replaced with a brand new battery in March and then in June or July checker replaced that new battery with another brand new one which is the battery I have in the hummer now so no way it went bad in three or four months so I'm pretty confident I won't have anymore problems with a new battery dying on us again. Or at least I hope not? Now I just need to replace the battery in our Ram truck which rarely gets driven because we drive the hummer all the time....

Off subject a bit but so ok we bought our hummer several years ago and my wife would t drive it and she took the Ram truck as her vehicle because its a beautiful quad cab 4x4 with very low mileage, its a 2002 Dodge Ram Quad Cab 4x4 SLT customized and fully loaded and she drove it for a few months but wouldn't drive the hummer, she's only 5'2" and 105 pounds so the hummer is pretty big to her, anyway after a few months of not driving the hummer she needed to run to the store but the truck was low on gas and really did t want to go put gas in it at the moment so my daughter and me talked her into driving the hummer which she was unfamiliar with how everything worked so our daughter went with her to show her how everything worked in the hummer so after startng it up and figuring everything out for a couple minutes she backed out of the driveway and off she went to the store, well several minutes later I see the hummer drive by the house and go around the block a couple times, well she was having so much fun driving it she wanted to drive a little longer and by the time she came home and parked it she was like a kid after their first pony ride and was really excited and couldn't stop talking about how much she loved driving the hummer and that was the last time the Ram truck was driven on a regular basis and it's been a few years... The Ram truck is a great vehicle and we never had any problems driving it and it was comfortable enough sitting in the custom leather seats, however after driving the hummer for a while our daughter hated the idea of riding in the ram truck, there would be times we would be getting ready to go somewhere as a family and our daughter would ask where I was and my wife would reply he's out in the truck waiting, our daughter would loudly exclaim WERE TAKING THE TRUCK????? in a very disappointing voice and my wife would have to say no no no, we're taking the hummer, I'm just used to saying the truck instead of the hummer and our daughter would be happy because to her the truck was uncomfortable to ride in after riding in the hummer for so long and the truck is t that uncomfortable to drive or ride in but we just stopped driving it on a regular basis.. Hell even I noticed a huge difference a few months later when we did decide to drive the truck and man it felt like riding on wood crates in a wagon with no shocks, it felt totally alien driving our beautiful truck so much that we just stopped driving it and since we bought our hummer the truck has had less then 100 miles driven on I which is why the mileage is sooooo low on a ten year old truck it only has 42k and even newer trucks that are only a year or two old have 80/90/100k on them and the only reason it has the mileage on it that it does is because we made two coast to coast round trips.... Anyway it only took one time driving the hummer for my wife to fall in love with it and stop driving her truck, which is why the battery would keep dying on it because of cold weather or long periods without starting it, we would use the remote starter to start and charge the battery once a week or so but even that would t keep the battery charged up... Anyway hope the hummer battery doesn't die again after trying this fix and if it does have more problem I'll update this post and let everyone know if it fixed the problem, because if it did t fix the problem I'll know tomorrow or the next day because from past experience the battery would die on a daily basis once this started happening the last two times so I'll know after driving for a couple days if this fix actually worked

BC

 

I had the same problem just started doing that

 

OnStar is the parasite where my H3 is concerned. I didn't pull the fuse or the box, just unsubscribed and it worked for me. Bought a Red Top about 2 years ago and it continued to drain out, would need to power up the battery every couple of days regardless of the weather. The last few months since cancelling my OnStar subscription, she fires up instantly after sitting for a few days, a week, no lag. Keeping the H3 in good shape is everything, cell phone/GPS, wing and a prayer and we're good to go. I read on another forum where someone had the same experience as myself, but others say unsubscribing isn't enough. Glad I didn't have to "pull the plug" or the box, saved time and headache.

 

the last reply here was from 2013 im hoping by now they had already figure what their problem was . H2 dont like weak batterys.

 

Had the same problem with my 04 H2. It was worse last winter when it got colder outside. Took the OnStar our years ago and put in a plastic pocket but forgot to pull the fuse for the system. Since the spring everything HSSE been fine. I have a dual Optima deep cycles (yellow tops) installed and it used to kill both on a cold night. Keeping my fingers crossed
Thanks for the advice will update on status
cheers,
Joe

 

My 2009 and 2008 H2 when sitting off and the key is out you can hear the map cd hard drive making noise. Almost like OnStar is calling it every couple of minutes to check its location. You can sit in your H2 and hear if this is happening. I have never had battery trouble in either H2 but always drove them at least weekly. I don't know which fuse in a 2008 or 2009 model to pull but I would be curious if the fuse was pulled weather the CD/hard drive noise would stop.