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Alternator, battery and charging question with plow use ?

Discussion in 'Truck & Equipment Repair' started by Maleko, Jan 23, 2011.

  1. Maleko

    Maleko Senior Member
    from Ct
    Messages: 781

    have an 05 gasser 6.0 2500HD i have the snow plow prep package with a 145amp alternator. I have a MM2 X-Blade plow , dual Viar compressors a 600 watt amp. i have dual batteries Optima red tops.( I know should be Yellows )

    My question is when Im running Normal the volt gauge is right around 14Volts
    as soon as i use the plow it drops down big time. But comes right back up when i stop using it. This means the alternator is working right?

    Also when i start my truck my compressors come on with the ignition i have a slow leak in the air system , The alternator is really working to charge the truck batteries and power the compressors. When its really cold it almost sounds like the alternator is squealing, like it struggleing to charge??

    DO i need a bigger alternator? Im just confused. It drives me nuts that i get such a drop when i use the plow??

    What are your thoughts? Thanks in advance
  2. theplowmeister

    theplowmeister 2000 Club Member
    from MA
    Messages: 2,617

    Have you ever seen the batterie voltage when starting the truck? The plow uses an electric motor (150 to 250 amps) that is BIGGER than most starters, so yes there is a voltage drop when using the plow, yes the alternator charges the batteries when the plow is not used.
  3. Maleko

    Maleko Senior Member
    from Ct
    Messages: 781

    Voltage is up past 14 volt sometimes when i first start it in the morning, then slowly goes down to right around 14 after a bit. Im assuming this is because after a long night of plowing the batteries are a bit low? then in the morning the alternator is charging them back up?

    i need to add a switch to my on board air compressors so they dont turn on right away when i start the truck. This must be making a big drain on the batteries as well as the alternator..
  4. theplowmeister

    theplowmeister 2000 Club Member
    from MA
    Messages: 2,617

    Maybe when you start the truck it starts on the batteries. so the alternator is charging them up.
  5. monson770

    monson770 Senior Member
    Messages: 133

    i had posted a couple weeks ago with a similar problem. i had severe voltage drops when using my plow, enough to cut off my stereo. i installed what the parts store had said was the HO alternator for my truck...
    well... the parts guy didn't hear me when i said 2002 2500HD, so i got a 130amp... went through their website after having my voltage problem, and discovered what the parts guy didn't do correctly when looking up my part.. he didn't hear me say HD.....

    so i went back told him, "i needed the REAL HO alternator", told him, "i already have the fused wire installed for it", and that fixed my problem.

    200amp alternator is probably what u should be using.. check with your parts store, make sure you tell them it's an HD with a plow..
    Last edited: Jan 25, 2011
  6. Mark Witcher

    Mark Witcher Senior Member
    Messages: 605

    145 amp alt is plenty for a plow truck. Its normal for the volt gauge to drop to 12 volts or less on any truck. If the alt wasnt keeping up the batteries you would have trouble starting the truck after shutting it off.