can't find source of battery drain
 

My 03 has had a battery drain problem for quite a while now but I've been to lazy and busy to really tackle it. Instead I installed a battery guard which automatically cuts the battery when the battery gets low. I find this device is always cutting my battery but at least I can start my truck after hit the remote to open the solenoid again on the battery guard.

Well I finally went out today to try and find the cause. I disconnected the pos battery terminal and then put a power tester light onto the disconnected pos terminal and the other end to the pos on the battery - sure enough there was enough draw that the power tester light was on (and quite bright too).

I then pulled every fuse from the engine fuse box, one at a time, to find the cause - none made any different. I then did the same exercise with the fuses on the driver side dash area, and again none made any difference???

So now I am confused. Are there are other fuse boxes in the truck?? If not, I guess my issue is with something not first running through the fuse boxes. Being that my truck is stock (no after market stuff) does this make sense. I thought all factory electronics went through fuse boxes??

I've read that the ignition switch can ground itself to the steering column and cause a drain - would this not go through one of the fuses too? If it does not I guess this may be a good place to start - how do I test my ignition switch if it is grounding???

Thanks

Re: can't find source of battery drain
 

I ran into this problem when I first got my 07. I took it into service and they couldn't duplicate it.

Funny part was they called me the next day, said it was fine and to come pick it up. When I got there they explained they could not find a draw and that there was nothing wrong. They tested the battery and load tested it and all checked out. The service manager runs off to get it and... dead battery :clapping:

They replaced the battery and I haven't had a problem since.

If you can... try a new battery.

Hope that helps.

Re: can't find source of battery drain
 

I start the truck and hook a volt ohm meter to the + and - terminals of the battery, voltage should be around 13/14 volts (maybe a tad more even), this will tell ya the battery is getting charged. Turn the truck off and check the voltage, should be around 12/13 volts. Disconnect both terminals and let it set over night and then check the voltage, gone below 12 it is dying and time to replace it.

Battery in my 03 has been replaced once so far in the 86,000 miles.

Ed

Re: can't find source of battery drain
 

To test for excessive draw you need to disconnect the Negative battery cable and put an amp meter inline between the neg cable and neg bat terminal. Should have no more than about 40mA draw. If it is higher then start pulling fuses. Common areas for draw are hvac, radio, onstar and especially any aftermarket devices.

Re: can't find source of battery drain
 

radio amp draw was a past issue a few of us had. ...especially on 03 an 04 models.

Re: can't find source of battery drain
 

We used to do it that way 40 years ago but used a simple test light. The old ways still work!

Re: can't find source of battery drain
 

I did some more reading, and then some more testing. Found tyhat actually the old way does not work. I actually found that I have asbsolutely no draw, but when I first used the test light method I thought I did.

The issue with the light is when you first connect one end of the test light to basttery post and other end to disconnected wire, the truck gets a connection to the ECU but the test light (or multimeter) does not have enough current so the ECU never gets past the delay and just keeps trying - thus the test light will remain on perm making it appear as a draw is happening. That is why the test light never went out even after I pulled ever fuse.

The proper method is to run a jumper wire (on aligator clips) when the battery post and the disconnected wire - this creates the connection allowing the ECU to activate and after 20 seconds shutdown. At this point you connect the test light (or multimeter) to the battery post too and the other end to the disconnected wire - now you disconnect the jumper. If the test light goes on you have draw, or if the muti reads more than .035ma you have draw. At this point you can open the door to test and you will see the test light (or multi) turn on and then off again in 20 seconds.

Anyway, this method showed that I actually have no draw at all (just like GM told me when they tested for draw when the truck was still under warranty).

The odd thing is my battery always slowly draw down and once weak the H2 alternator never gets it back up even on long highway trips? When the battery is weak I need to charge it with an external charger. When this is done, the battery is strong for 3 months but eventually starts to weaken and again the alternator never gets it back.

Could the issue be that I have a cheap Costco battery that is actually slightly less cold-cranking amps than the original? I've read that the factory battery was just on the border of being adequate - perhaps my 'smaller' battery is being used more than the alternator can feed it?

Thanks

Re: can't find source of battery drain
 

That was my problem as well... Mine would sit a week or so and then i'd have to jump start it. The battery always charged back up but would die in a few days.

If Hummer didnt replace my battery i was considering an optima battery as from what peoople have said here.. they seem very happy with em.

Re: can't find source of battery drain
 

I have put 2 of the optima batteries in and now I need a new battery again! I was told that vibration is not good for these gel batteries, Dont know how true that is but I'm tired of jumping this thing....Trust me 2 optima batteries at $200 a pop in less than 2.5 yrs I'm going back to the oem style at $134... I will not buy them again.

Re: can't find source of battery drain
 

Wow... I would agree with you there. 2 in 2.5 years is a bit much.

Re: can't find source of battery drain
 

how do you cure the radio amp issue? is it as simple as replace the radio?

Re: can't find source of battery drain
 

My problem with the battery drain was the OnStar. Now that I've pulled the fuse on it I have no problems, even if it sits for a week.

Re: can't find source of battery drain
 

just pulled my onstar fuse wish me luck!

Re: can't find source of battery drain
 

Took H2 and battery back to Wallymart, battery had a bad cell? They tested my charging system and all is good according to their machine! Got a replacement under warranty. Stay tuned!:perfect10s:

Re: can't find source of battery drain
 

We pulled the OnStar fuse also about 2 weeks ago and so far so good.
Ours only dies after 4 days to a week and when the temperature drops
below and the temp drops below 40.

Re: can't find source of battery drain
 

To the poster who replaced two opitmas, they have a warranty for life or it might be 3 years.

I just replaced my red top after I went dead at the ski resort. Also added a priority start, Google it. I got mine from batterystuff.com

It shuts off all draws at 11.7 volts. Re-activate it with the press of the brake pedal. Slick ****!