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Battery or charging issue

Discussion in 'Truck & Equipment Repair' started by rb8484, Dec 9, 2009.

  1. rb8484

    rb8484 Senior Member
    Messages: 419

    Hi guys. Finally had my first push last night, and now we are under a blizzard warning until tomorrow evening.
    This is a new truck to our fleet, and I was running it last night. I belive the battery is getting weak or my alternator is getting weak. When you hit a function on the plow, the battery light comes on on the dash and lights really dim. If I run my strobe light, the light cuts out when I hit a function on the plow, its like the plow takes all the juice and starving the strobe for power. Can I test the alternator with a volt meter. Will it give me an idea if it is getting weak? What should be a good reading? The truck is a 2000 gmc 2500 with the 5.7L. How many amp alternator should I run on this?
    Thanks in advance
     
  2. clark lawn

    clark lawn PlowSite.com Addict
    from NE ohio
    Messages: 1,233

    a volt meter will only tell you how many volts the alt. is putting out not the amps. go to a auto parts store and have them test it. you will want at least 100 amps, depending what else your running in the truck you may want to step up to an even bigger one.
     
  3. rb8484

    rb8484 Senior Member
    Messages: 419

    Yeah, I was hoping I could avoid taking it off just to see if it is getting weak. I have a load tester that I am going to test the batteries with, if they test ok, then I guess i will be taking the alterntor off.
     
  4. LEVE

    LEVE Member
    Messages: 79

    Take a look at the cables and connections. It could be something as simple as corroded connections or a bad cable. Also make sure the grounds are good. From your description, I'd say your charging OK, the battery's OK but the grounds may be corroded causing a higher than normal current draw.

    Are any of the larger cables heating up to the touch?
     
  5. farmer1009

    farmer1009 Junior Member
    Messages: 25

    Chances are it is the alternator starting to go. Take it in to have it tested, but you don't have to buy one from the parts store. Try to find someone locally that rebuilds alternators, and have them up the amperage on it when they rebuild it. My truck's alternator puts out close 130 amps. Rebuilding them and upping the amperage is usually a little bit more expensive, but it has proved to be helpful to me. Especially if you run a salter and plow.
     
  6. grandview

    grandview PlowSite Fanatic
    Messages: 14,609

    If your getting the alternator checked ,get the battery checked too .
     
  7. rb8484

    rb8484 Senior Member
    Messages: 419

    I was just told by someone that you dont want to amp them up from stock as it can screw up the electronics. I never heard this before.
     
  8. larrylaverne

    larrylaverne Member
    from ill.
    Messages: 46

    make sure alt. belt is not loose
     
  9. old skool

    old skool Senior Member
    from NW IL
    Messages: 167


    Ditto... In the "old" days with "v" belts, that was a definate problem. Today with serpentine belts,not as big a problem...But I agree, check the belt tensioner. Also,how old is the belt? A glazed/worn belt wont hold the "pull' of a hard working alternator as well as a new one.
     
  10. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    Do your best to not listen to that "someone" again when they decide to give you any so called helpful info when it comes to vehicle electronics.. Because he has no clue what he's talking about.
     
  11. grandview

    grandview PlowSite Fanatic
    Messages: 14,609

    Gospel according to BB!
     
  12. old skool

    old skool Senior Member
    from NW IL
    Messages: 167

    BTW, how old is the battery? How long were you plowing before you started having problems?
     
    Last edited: Dec 9, 2009
  13. farmer1009

    farmer1009 Junior Member
    Messages: 25

    I have never heard of any problems occuring from amping up an alternator, but I am by no means an expert on the subject. I know in my '99 Roush edition F-150 I had the alternator worked up to a really high amperage to support the lights and sound system in it. I never had a problem with it, but that not saying you won't.
     
  14. clark lawn

    clark lawn PlowSite.com Addict
    from NE ohio
    Messages: 1,233

    you dont have to remove the alt. to get it checked alot of the new machines will test the battery, alt. and starter while they are on the vehicle