I seem to have a problem with something draining my battery. THE BATTERY IS NEW - (Got it in January).

Whilst I was away on my 2 week break,my daughterused the Blazer a couple times. Each time it had to be jump started. Leaving the battery on charge overnight did not helpso I suspect it is now terminal.

Previouslythe truck was used daily or at last every other day & there were no issues & the gauge had always indicated all was well, but if left for 2 or 3 days the battery died.

I'm told that the onboard computer may be able toidentify the source of the drain. Is this true as I don't want to go to the Chevy guys & ask them to plug it in if it can't be done.

Any suggestions what can be doing this or are there any suspects to check first.

By the way, before I left I had removed the fuse for the roof lights so it can't be them. I don't think!

 

When I've seen batteries go bad that fast it is either usually from a bad battery/shorted inside or an alternator short that drains power from it. Security systems, clocks and other stuff can drain power, but not generally that fast. Other things can also drin, but you will need to test for problems and drains on those circuits.

Since your Blazer had drained batteries previously then you need to start checking for drains.

 

The OBD2 system will not be able to identify the source of the drain. You basically need to run down through the fuses, pulling them and putting them back, one at a time until you find the source of the drain (multimeter is required). Some systems may have a high initial current draw, but should step down in amperage when they go to sleep.

Maximum current draw should not be over 100mA after you have waited 5 minutes.

Basically, remove the negative battery terminal, set your multimeter to AMPS, put the multimeter in series with the battery and watch the current draw. It may be as high as a few amps when first connected, but after 30 seconds it should drop down significantly, then after 1-2 minutes it should drop again and be at its steady state level. If this exceeds the amperage above, you need to start messing with the fuses to find the circuit that is at fault.

What are the chances that the dome light was left on while you were away? Is there any aftermarket electronics (stereo, remote start, etc) installed?

 

Pretty sure the dome light had not been lefy on & no, there are no aftermarket accessories - other than the tow hitch which I see had been hooked up to the rear lights.

I'll get someone to run the tests with me.

Thanks guys.

 

Thought I had a drain too. Turns out the NEW battery I bought had 2 bad cells which gave similar symptoms to yours. IF the battery checks out ok. Run an ammeter on the +ve side with the ignition off to see if you've a bigger current draw. One last thing. Check the connections at the post. The dust boot can get trapped between the mating faces and thus give a poor contact which could give bad charging/recovery.

 

Yah I drained a battery overnight by the rear dome like for the liftgate window. Its easy to accidently push the hatch button and that will turn the light on if you have it switched with the hatch switch. I turned mine off after this incident to avoid jumping it again.

 

On Wednesday the battery was flat so I could not do any checks but put the battery on charge for 24hrs & achieved 11 volts. Friday I returned the battery to the supplier (which was only5 months old) & he confirmed it was dead & replaced it free. This time for one with additional terminals on the top. The old one had them on the side only & fitting jumper leads was a pain in the a***.

The alternator checks out ok. sonow that all seems well I'll keep an eye on the voltage. If there is a drain issue I'll address it then.

 

The previous owner of my '96 Blazer says that there was no problem with the Blazer when he had it. I have had it for about 3 months now and I have had the ame problems with the batttery draining. He had the Ungo security sytem w/ remote start installed would that be a part of the problem?

James