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dual battery setup 2004 1500 z71

Discussion in 'Chevy Trucks' started by captainquad, Dec 11, 2005.

  1. captainquad

    captainquad Junior Member
    Messages: 10

    I have a 2004 chevy 1500 z71 that came with one battery from factory. I have now installed two identical bigger batteries and have noticed that they seem to leak a bit of acid. I am running them positive to positive and aux battery negative to the front of the passenger side cylinder head. I alreayd burnt one of the batteries because I am guessing they werent the same, and was discharging to the old batteries level. Now i put two new ones exactly the same, and it seemd to be doing it again? Im stuck, I used good cable and also have a 145-165 amp alternator? I increased the alternator wire as well? Not too sure what going on, but it getting pretty expensive. I just hope i dont have to replace any more batteries. Any help?

    thanks
     
  2. Joe D

    Joe D Senior Member
    Messages: 605

    Is the alt over charging? It sounds like the batterys are boiling over. Check the volt output and make sure it's not over 13.5 max and also check that something is not digging into the battery like a sharp edge on the tray.
    Where did you mount the battery? i know that a 2nd battery is available on the 2500 and 3500 trucks.
     
  3. captainquad

    captainquad Junior Member
    Messages: 10

    well i mounted everything properly with the tray from the dealer for the 2nd battery option, and I just bought one of those digital volt gauges that plug into the cigarette lighter, and noticed that when I started my truck, the voltage went to 15.1, 15.2, 15.3, then after a while dropped down to about 14.4 +- It was constant around 14.4 or so? Is that too high? The only time it dropped down was went I plugged in my rotating roof light, and then it dropped to about 13.9v. I dont know why it would go so high? If the alternator is overcharging, shouldnt there be a regulator to prevent that?
     
  4. Bad Luck

    Bad Luck Senior Member
    Messages: 741

    At start up my trucks voltometer spikes as well. I have two same age Interstates. Hooked up + to +, - to -. I did not ground the aux battery to the frame but to the other battery.
     
  5. captainquad

    captainquad Junior Member
    Messages: 10

    Have you noticed any of your batteries boiling over or leaking acid?
     
  6. 99 z71Silverado

    99 z71Silverado Member
    from Chicago
    Messages: 41

    I always thought in ideal conditions your alternator should be putting out 14.4 volts. I installed car audio at best buy for a couple of years and most vehicles are running 14.4 volts
     
  7. captainquad

    captainquad Junior Member
    Messages: 10

    well thats what it was putting out when the truck seemed to warm up a bit. But when i started it, it was at about 15.2v. I thought that would be a little high?
     
  8. 99 z71Silverado

    99 z71Silverado Member
    from Chicago
    Messages: 41

    how long was it running that high?? it doesn't seem right to me- i don't remember seeing cars/trucks run that high. Most cars/truck will normally run a little under 14.4 volts when at idle.
     
  9. Bad Luck

    Bad Luck Senior Member
    Messages: 741

    No.

    Try grounding them together and see if that helps.
     
  10. captainquad

    captainquad Junior Member
    Messages: 10

    So what your saying is get the negative from the aux battery, and connect it to the negative side of the main battery? Thanks
     
  11. djd427

    djd427 Member
    from NEPA
    Messages: 98

    Take the ground from the cyclinder head. Hook it to the frame or negative on other battery. When I installed my 2 sets in my trucks, I couldn't get a good ground from the motor.
     
  12. captainquad

    captainquad Junior Member
    Messages: 10

    Thanks, Im gonna try that, I have been watching the gauge, and actually it has been in and around the 14.4v mark, but im not taking that too seriously if there is acid leaking from the battery!!:dizzy:
     
  13. 99 z71Silverado

    99 z71Silverado Member
    from Chicago
    Messages: 41

    where are you guys putting the 2nd batt. there doesn't seem to be any room under the hood. i got a 99 silverado with 5.3L
     
  14. TLS

    TLS PlowSite.com Addict
    Messages: 1,425

  15. djd427

    djd427 Member
    from NEPA
    Messages: 98

    not 2 sure on a 99 but on my 2 trucks they are on the passenger side against the firewall, right above the tire. Do a search for it there are alot of pictures on here for them