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New truck (to me) Dead Battery Again

Discussion in 'Chevy Trucks' started by G-rott, Aug 23, 2003.

  1. G-rott

    G-rott Junior Member
    Messages: 19

    Hello all,

    I am looking for some help. I have been lurking for some time and thought you guys would be a good source for information.

    I purchased a 2000 GMC SC 2500 4x4 with the Plow Prep Option this spring. I had been running a similar 1500 w/o the plow prep.

    I am a builder and I drive alot. Mostly town to town on the highway. The problem is I have had a dead battery three time this year with the 3/4 ton dual batteries and all.

    Before this with the 1/2 I had two or three in the three years and 60000 miles I drove it. Each of those times I could understand what I did to kill the truck.

    The latest with the 3/4 ton I beat the crew to work by 20 min and sat in the truck w/ the radio on and my coffee and waited for the first of them to get there. We took one of the guys trucks to lunch and at quitting time my truck wouldn't start. Lucky for me one of the guys was still on the site.

    What Gives? Is it possible to jump from the "extra battery" to the regular one? Or am I draining both of them somehow??

  2. Pelican

    Pelican 2000 Club Member
    Messages: 2,075

    When you are playing the radio, do you have the switch on "Accessory", or switched past off one click backwards? This gives you the least amount of draw on the system.

    If you have the key turn to "On", or one click forward, you've got the ignition and fuel pump energized along with other circuits that draw a lot more energy and could be causing your problem.
  3. JohnnyU

    JohnnyU 2000 Club Member
    Messages: 2,037

    These dual batteries were a factory option, right? They have an isolator module to keep one from draining the other, unless the batteries were added later and just tied + to + giving 12 volts, but 2x the current reserve.

    I'd have a dealer check the truck, my dad's 00 has a feature that prevents teh battery from being run down, I think it shuts it off after 45 minutes. We left the dome light on one night, it was off by morning, but the truck was no worse for the wear.
  4. wyldman

    wyldman Member
    Messages: 3,265

    You would need to do some testing,to find out what's going on.

    If both batteries are dead,then maybe it's not charging properly,or you have a pretty big draw.

    If one battery is dead,then maybe a problem with the isolation circuit,or one bad battery.

    If the extra,or second battery has power,you could try to jump it from that battery.
  5. G-rott

    G-rott Junior Member
    Messages: 19

    Me again

    I actually turned the key off and left the radio on until I got out, it shuts off when the door opens. I'm really confused buy the dead battery thing. I think the regular battery is the one that is dead but I have not checked the "extra" one for charge.

    How does the isolator work and can it be by passed for emergency starting?



    ps Yes this is the factory dual battery.
    Last edited: Aug 24, 2003
  6. snowjoker

    snowjoker Senior Member
    Messages: 283

    Maybe you can unhook one of the battery's and run a single battery to possibly isolate the prolbem. Maybe one has a bad cell.