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alternator identification?

Discussion in 'GM Electrical Tech' started by quicksilver8817, Nov 6, 2012.

  1. quicksilver8817

    quicksilver8817 Rockstar 100 Posts

    how do i figure out which alternator cam on the factory setup of my 2001 gmc 2500hd 4x4 .. it does have plow prep.the alternator has been replaced once by previous owner . i notice a 105amp , 130amp , 140 amp replacements available from autozone .. can i use any of those ore does it have to be a factory spec one?
     
  2. T-bone

    T-bone Rockstar


    You can post a picture here and someone will likely be able to tell you. Also remove it and bring it to your parts store and compare to the different flavors available. Shoot off the hip guess is that you can rule out the 105, its either the 130 or 140. Autozone is fine but get the right one
     
  3. Pikey

    Pikey Moderator Staff Member 3 Years ROTM Winner 1000 Posts

    you could always try putting the vin in here http://www.compnine.com/vid.php It will tell the rpo codes and what they mean. It should tell you what size was on it from the factory
     
  4. quicksilver8817

    quicksilver8817 Rockstar 100 Posts

    i mean i guess what im asking is if the 145amp fits correctly , would it hurt anything to run a higher am alternator?
     
  5. T-bone

    T-bone Rockstar

    hard to say.

    more juice higher incidence of blowing fuses...

    unless you have a specific need stick OEM
     
  6. Conlan Rose

    Conlan Rose Active Member 2 Years 1000 Posts

    Alternators have a built in regulator that prevents sending out to many amps it works on an on demand basis.
     
  7. Crawdaddy

    Crawdaddy ↑↑↑ Has no life Staff Member 5+ Years 1000 Posts Platinum Contributor

    Yep, going with a higher amp alternator won't hurt anything so long as it's the same series of alternator and fits in the bracket.
     
  8. quicksilver8817

    quicksilver8817 Rockstar 100 Posts

    thanks guys .. i do have certain needs , i plow so between running the plow , strobes , and whatnot i feel better having a higher output alternator .. i think i may also run a second battery too.
     
  9. Conlan Rose

    Conlan Rose Active Member 2 Years 1000 Posts

    A few things:
    1. Second battery only increases power when starting and helps add capacity to running stuff when the truck is off, for when the truck is on the alternator does all the work
    2. you might want to look at a bigger than factory spec alternator if you are running so much stuff. A Lot of people on the site are getting into DC power alternators they are ridiculously powerful and reliable. This Christmas I'm getting one for my self :glasses: site: https://www.dcpowerinc.com/high-output-alternators.html?make=GMC&model=Sierra&year=2001
    3. An extra battery can be wired a couple different ways. Way one: easiest only need the second battery relay 2 new batteries and cables for second one, I'm not going to fully explain it but all you are doing is adding a second starting battery. Way two: both batteries are charged by the alternator but they run different things, one is dedicated starting battery other runs accessories this is the best way because you don't need to worry about running down you starting battery when running lights and stuff, but this way is much more difficult to set up. Either way bother batteries must be the exact same age, type, amps, and brand or it can cause problems.
     
  10. PantheraUncia

    PantheraUncia Active Member 2 Years 1000 Posts

    The 105amp is the "standard alternator" I have that in my 2000 1500. The 135 or 145 amp was for heavy duty applications like the snow plow prep package...... Funny thing now is the standard alternator on a 1500 now is the 145 or a 165 and the heavy duty is bigger.

    If you have allot of stuff you plan on running you can get a 350amp alternator after market for your truck for some serious $$$$$
     

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