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Charging System Wiring

Discussion in 'Chevy Trucks' started by s--k, Jan 6, 2016.

  1. s--k

    s--k Junior Member
    Messages: 12

    OK, been doing lots of reading tonight and a head full of opinions and food for thought, but now I want to pose my specific issue with you all. Lots of threads on here about high output alternators, but not too many get into specifics on wiring.

    First, 1988 Chevy K3500 454, just outfitted with a Western Pro Plow.

    In getting this truck ready for first season of plowing I'm going through a bunch of things as time permits (weather has been permitting).

    I checked the OE alternator and it is putting out 30 amps at idle and 50 amps at 2000 rpm. This sounds about right for a OE CS130 alternator which produces peak power of 100 amps at some high engine rpm that I will rarely be at. I checked the output with my snapon microvat tool.

    So that kind of output at those rpms is not going to fly.

    I buy a Powermaster 95a/145a alternator, the 95 amp output being on the idle side of the spectrum. 145 amp somewhere at the highway speed/rpm spectrum. Powermaster does not sell a direct fit higher amp alternator for my truck, other companies do, but Summit had this in stock and it was priced reasonable.

    So then how to wire?

    My truck has about a 5' length of 8 gauge wire from the alt to the power distribution bar on the firewall and then another 5-6' 8 gauge wire goes from this power distribution bar to the battery. There are OE fusable links on both wires.

    I was going to upgrade this wire to 6 gauge due to the higher amp and the length and then dug into how it was wired exactly and started to think that I could run a wire directly from the alt to the battery. The plow is connected right at the battery and all other vehicle power is coming off this power bar on the firewall. With the highest amp load on the truck (the plow) being on the battery I figured it would be good to have the alternator go direct to the battery.

    So I call Powermaster and they start telling me for 11' of length I need like 4 gauge wire, which I already knew, but I asked them if I can run a wire right to the battery at like 6 gauge which would be maybe 4-5' and they said yes. Then I said but what about the power bar on the firewall, can I run the wire from the alternator to the firewall like it is now? And they said yes just make sure the gauge is the right size. Then I said, can I run a wire to both the battery and the firewall power bar from the alternator and they said yes. I don't know myself it that was a good idea or not, but they said yes.

    Now I'm thinking that running 2 wires from the output of the alternator to two different locations is a bad idea. I'm based off of reading tonight I'm thinking of keeping the OE wiring method and just upgrading the gauge although i don't know what to do about the fusable links.

    Maybe I can just go right from the alternator to the battery and keep the wire from the battery to the power bar on the firewall. Remember currently it goes Alt > power bar > battery. I'd be going Alt > battery > power bar.

    What say any of you? Hoping to have this wrapped up tomorrow night or Friday morning at the latest.
  2. s--k

    s--k Junior Member
    Messages: 12

    Something I read tonight here is shaping my view on just upgrading the OE wiring size and keep the routing: http://www.pirate4x4.com/tech/billavista/Wiring/Part2/

    The thing that makes me want to wire direct to the battery is that the plow power comes off the battery and there will be high amp draws there.

    Thanks for any input you have.
  3. s--k

    s--k Junior Member
    Messages: 12

    To button this up if anyone is interested, I reread that incredibly indepth "alternator bible" and realized I was taking that quoted portion out of context.

    The author was a big proponent of using the sense wire on the alternator at the charging/draw source. OE my alternator uses the output voltage as the sense. If I did run a wire from the alt plug to the power distribution block on the firewall, then I shouldn't go straight to the battery.

    In my case the way it is, from the alternator I ran two wires: a 6ga wire to the batt with a 200 fuse and left the factory 8ga wire with fusible link going to the firewall power block. I eliminated the OE wire from the batt to the power bar.

    Just a little different than how it was stock, but all is well. And this way with the plow power coming straight off the battery, I have the alternator connected straight to the battery so any high amp flows don't have to go all the way to the firewall and then to the battery.

    Everything seems to be working fine. Just need some snow now. Looks like tomorrow night.