Alt. Output

[markm]

Spent the day working on a 71 GMC 4x4 with a plow and salt spreader, I have 14.15 volts at alt and 13.88 at Bat. I would have like to have seen less drop. It has a 94 amp 10SI off an 87 GMC. What do you all think is normal, I was thinking about two tenths drop.

[chevynut]

It depends on the load. How much current are you drawing? How long is the wire from the battery to the alternator, and what size is it? Where are you sensing the voltage?

[markm]

Duh, runs through the OEM 14 gauge charging wire, its a non ac cab probably had a 37 to 45 amp alt. I had thought about the LMC Truck adaptor but not wire size. Thanks.

[chevynut]

I think 14 gauge is way too small for a charging wire. I'd go 10 gauge at least, possibly 8 gauge. Also if it has a sense wire you can move it to the fuse box...that's what I did on my Nomad with the CS130 alternator.

[markm]

Both of my 87 GMC 4x4s are equipped with a 94 amp 10SI with an 8ga wire from Alt to Bat. Would I be correct in adding a 10ga wire to this truck and leave OE 14 in harness. If its not hooked at battery whole truck is dead.

[chevynut]

Why would the whole truck be dead if you take off the charging wire from the alternator to the battery? The fuse box should still be connected to the battery somehow. Perhaps the wire from the alternator also goes to the fuse box? Is there more than one wire on the alternator terminal?

I guess I don't see anything wrong with leaving the 14 gauge wire in parallel, if it goes from the charging terminal on the alternator to the battery. In fact, it makes it work like a larger wire so perhaps you don't need an 8 gauge wire.

[markm]

My 67 Camaro, 72 Cheyenne and 72 Blazer are all wired this way, but remember they all were equipped with externally regulated alternators when new.

[cardoc55]

Always use a fuse on 8 wire, maxe 80 amp.

[markm]

Added a 10 gauge wire from alt to bat yesterday leaving factory 14 gauge in place. No voltage drop now, I cut wires to the POS Sony radio and no more voltage drain while parked. These new car radios are good for nothing except running down battery's.

[Rustaddict]

Added a 10 gauge wire from alt to bat yesterday leaving factory 14 gauge in place. No voltage drop now, I cut wires to the POS Sony radio and no more voltage drain while parked. These new car radios are good for nothing except running down battery's.

Almost all the music that gets played these days ain't no good either. I used to think cutting radio wires was a crime but haven't felt that way in years. It's no surprise that demand for radio delete plates is so strong.