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Discussion in 'Chevy Trucks' started by viper881, Oct 11, 2011.

  1. viper881

    viper881 Senior Member
    Messages: 477

    I have a 2003 Hd. Just went through my 4th alternator in my truck and I have only 64000 miles on it. Any ideas....I just run a blizzard front blade. I keep putting the stock alternor back in, which is a 105 amp. I found a different brand 145amp. Any body else have experience or ideas for me?
  2. captadamnj

    captadamnj Senior Member
    Messages: 148

    Key to alternator performance for typical pickup snow plowing applications is output at low RPM's. Stock 100 amp alternators are usually putting out less than 40 amps at idle - 1000 RPM's. This is typically insufficient for our charging needs. You want an HD alternator that is putting out 100 amps at low RPM's, then you've got what you need.

    Beyond low RPM output, next consideration is the killer for alternators - heat. Paying for better quaility heatsinks and better windings in an alternator is generally where the more $$ comes from, and quite simply, you get what you pay for in heat dissapation.

    Finally, if you go to a larger alternator, be sure to upgrade your wiring from the alternator to your batteries. The stock wiring with a H.O. alternator is like having a pumper outside your house to fight a fire but only hooking up a garden hose to it.

    Before you do any of the above, I would check your batteries and all connections. Trying to charge a bad battery can kill alternators and trying to charge a good battery through poor connections is almost as bad.

    If you do a search of the forums for high output alternator, you'll find plenty.
  3. viper881

    viper881 Senior Member
    Messages: 477

    Thanks for the input! I checked the connections and everything looked ok. I have two batteries in the truck. One battery is hooked up to the alternaor and the 2nd battery looks like its just hooked up to the first battery. Thats correct is it not
  4. sweetk30

    sweetk30 PlowSite.com Addict
    Messages: 1,588

    quality battery . full charged battery . clean conections on all power points from battery to starter / plow/ what ever. as corrosion = more amps draw = more work for alt.

    stock just cuts it barly for 98% of stock vehicles. start throwing big loads and watch it die.

    even if stock alt replace alt positive to batt cable with min 4 ga wire or better. also dont forget grounds from frame to engine to body to batt.

    then if problems you need bigger alt. like said look for dyno sheet with alt and you want at least 1/2 the amps min at idle and full output at around 2000 or so rpm as you are prob not seeing full speed rpm all the time its stop and go stop and go.

    the alt cant keep up with this . its like the garden hose to the pumper truck that was said. it dont work.

    i added a aftermarket alt to my truck fw years ago. 210 amp unit. at idle 800 rpm it shows output up to 125amps if needed. then by 3000 its 215 amps . so its better than advertised. also added the big power cables from alt to batt and grounds. now i can have everything on and running with zero problems. and thats with a 1000ca batt.

    also fixed the shop plow truck were i used to work it was eating alts just like you. i plowed 1 storm with it and it had to catch up 3 times to charge batt or i was dead. watching volt gauge it was barrly getting 12 volts when moving cause the truck was stop/go and small lot runs but big lot.

    boss said no go on big alt. so i swaped on a 1/4" smaller pully and shorter belt and BAM fixed the problem. made the alt think it was running faster like normal. yes its a bandaid but the truck dont leave the shop as dd use. so its cheep and worked perfect. so it goes to show you how it works all together.

    and 2 batts hooked together is normal but dont forget = longer before you finaly have to play catchup . then it takes 2x longer to catch up and the alt is going full bor longer and creating more heat in the end. and heat is the #1 killer of electronics basicly.
    Last edited: Oct 11, 2011