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2008 Silverado/Fisher Plow voltage issue

Discussion in 'Truck & Equipment Repair' started by 2004blkcorvette, Jan 17, 2011.

  1. 2004blkcorvette

    2004blkcorvette Junior Member
    Messages: 5

    I've read all the post I could and followed all the directions BUT . . .
    I have a 2008 Silverado 2500 HD with the 160 Amp Alternator (OEM). I have an 8" Fisher Minuteman II plow set up - installed by professionals. I have burned through 2 OEM Batteries in 2 years. Took to dealership and was told Alternator meets spec, they said must be my plow motor. I went home and tested the amperage of my plow motor and get 157 - 169 amps DC, which should be normal for the Fisher 2KW motor at 12+ vDC. So I came here and read all the posts I could ingest. I upgraded the "Big Three" with 2 AWG Ground wires and 4 AWG wire from alternator to maxi fuse block. I purchased two new Optima Yellowtop D34/78 batteries and installed them in parrallel with 2 AWG wire as instructed here and elsewhere. YET, when I raise the plow I still get a voltage drop from the normal 14 vDC to just below 12vDC. When the truck was new this meter did not budge. WT* do I do now??? I need Expert Advice.
     
  2. stacks04

    stacks04 Senior Member
    from ct
    Messages: 119

    Maybe look into the napa 250 amp alt kit. I just priced it out the other day and it was about 300 bucks, but since you have done the cables already then you would only need the alt for about 200.
     
  3. t-sig

    t-sig Senior Member
    from 607
    Messages: 121

    Stacks04,

    I think you will always see a certain amount of voltage drop when you run a plow. The alternator just can't maintain 14 volts on its own. Just looking at your numbers, you have a 169 amp draw and a 160 amp alternator output. And that output is likely at high RPM's. One thing some people are doing is putting a smaller pully on their alternator to spin it faster at idle. If you aren't running out of juice by the end of the day, I wouldn't sweat it.
     
  4. Andy96XLT

    Andy96XLT Senior Member
    Messages: 323

    I don't think dropping from the normal 14.4 to 12 under load is bad at all. Does it jump back to 14.4 once you release the controller?
     
  5. 2004blkcorvette

    2004blkcorvette Junior Member
    Messages: 5

    Yes voltage recovers, but slowly over time, not immediate. The single battery did the same. From what I've read it is the voltage cycling up and down that killed the OEM battery twice. Maybe the Optima's can handle the cycling and won't fail, but I would have thought with two of them there would be no or very little cycling of voltage.
     
  6. 2004blkcorvette

    2004blkcorvette Junior Member
    Messages: 5

    Thanks to all. I will see what happens and leave it as it is. I'm pretty sure this will get me through this winter and if something goes bad next winter, I guess I will look into the alternator upgrade. Just pisses me off that GM sells a truck and charges you $1,100 for an OEM "plow package" which in the end has little or nothing to do with actually running a plow!
     
  7. Andy96XLT

    Andy96XLT Senior Member
    Messages: 323

    I am not very familiar with the new chevys but do you know if your voltage regulator is a standalone unit or if it is built into the alternator? I am thinking maybe your voltage regulator has something wrong with it which could show some signs you are seeing. Your voltage should really jump back almost immediately once you are no longer under load. This kinda hints a voltage regulator issue. Just a thought!
     
  8. mbaldasaro03

    mbaldasaro03 Member
    Messages: 47

    i have an 08 chevy 3500hd with a gas motor and it does the same thing also the plow relay has been getting louder every time i move the plow