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2008 2500HD 6.0 Gasser Dual Battery Question

Discussion in 'Chevy Trucks' started by robertbick, Dec 28, 2011.

  1. robertbick

    robertbick Junior Member
    from NY
    Messages: 15

    Hello all. I have an 08 2500 with the factory dual battery option but not the plow option. I have noticed that the driver side battery is always at or above 12.8V (100%) but the passenger side battery is usually 12.1-12.3V (50-70%). This voltage is checked after the truck has been sitting for a few days and up to a week.

    My truck is not used much and sits in the garage up to a week or two between uses. Could it be because any accessories like the clock that draw power when the truck is off only draw from that one battery? I have not used the plow before checking this voltage.

    Is the primary battery the one on the drivers side or the passenger side? When I bought the truck new from the dealer, they also installed the Fisher plow. The plow is powered off the passenger side battery. Is this correct?
  2. dieselss

    dieselss PlowSite Fanatic
    Messages: 10,739

    if its the same as our factory systems, the pass battery is controlled by the computer via a solenoid. It only uses this battery when it needs to. Check to see if you have big or small wires running to it.....not the plow wires. That will tell you if its primary or not.....right or wrong i have disabled the factory setups on our trucks and hooked both batts together.
  3. calhoun

    calhoun Senior Member
    Messages: 165

    08 truck (900) I believe the primary battery is now on the passenger side. That means the passenger side battery is powering all the "hibernating" electronics and the secondary battery, on the drivers side, is not connected to anything (untill the engine starts) thus the difference in voltages.
  4. robertbick

    robertbick Junior Member
    from NY
    Messages: 15

    Yep! Just found this out also and you are correct.
  5. jklawn&Plow

    jklawn&Plow Senior Member
    Messages: 469

    My 2011 (1yr old) has same voltages, 12.8-driverside, 12.4-passenger after sitting. Passenger side is main battery and runs the plow. In 4-5 yrs I might do a dual install and run them in parallel. Then hook plow to the drivers side and decrease length of wire to plow and closer to alternator.
  6. FuturePilot4u

    FuturePilot4u Member
    Messages: 72

    i have the option for dual batteries, tell me- can you tell a big difference in performance and what are some perks of it???

    also do you need another alternator for a 2nd battery or do they connect to the same battery?
  7. jklawn&Plow

    jklawn&Plow Senior Member
    Messages: 469

    Factory setup, it just is there as a backup and for the trailer. Even need jumper cables to use it I think. If you wire up a dual battery in parallel with the other one it provides Double the amperage at 12V so twice the power. One really good battery is better than 2 bad ones and is comparable to two mediocre ones. So depends on what your powering.