The Stovebolt Site Forums The Shop Area The Electrical Bay I need help with my new alternator

Ok, so I have a 54 Chevy Truck that I got from my Uncle. He said it was re-wired to 12v however I'm finding a lot of what he said "should have been fixed" wasn't really fixed on the truck. So, I've been replacing one thing after another and now I'm working on installing the alternator because my generator crapped out on me. I went to alternator shop and they sold me a 100amp chrome alternator. The rep said it was a one-wire alternator however it also has the tabs for a GM plug, so I'm not sure if this is really a one-wire, three-wire, or both???

Yesterday I was able to wire everything up and it seems to be working fine. Although, I did have to bypass my Ammeter (I ran a jumper wire from each pole) in order to get it to work. However, I've been doing a lot more reading and have been somewhat scared that my 100amp alternator might fry my current wiring setup and that keeping the Ammeter may be a bad thing down the road.

So, I'm not too sure if I wired everything correctly and/or if my wire gauge is properly sized for the 100amps. Eventually I might replace the Ammeter with a Voltmeter just like its done in the Tech Tips. For now, I'd like to rest easy that my wiring isn't going to catch my truck on fire or shock the life out of me. Any info is greatly appreciated.

Not too sure what your question(s) are, or name.

Not sure what ammeter you have, maybe you can tell us the range of the scale.

The links to the pics on my computer are not functioning.

100 amps is a lot an can cause a lot of problems. Old original wires can be hazardous. Does not mean you need to wire the entire truck, just alternator to battery.

You really do not need a 100 amp alternator, it's really for vehicles dual AC, electric windows, electric sun roof, trailer with battery and big wattage stereo/speakers.

So seldom will 100 amps ever flow through the wires except maybe for a short period charging a really low battery.

Sorry to say I think the alternator shop guy sold you much more than you really needed. And chrome, did you want chrome?

Mike

I think you fried your link..............not working for me

Sorry for not being clear.

My questions are:
1. Will my alternator be too much for my current application?
2. Is my wiring correct

I'm sure #2 can't be answered until I can figure out how to get my photo links to work properly. I'll work on it.

Original ammeter? Range of ammeter? Original wiring or did Uncle install larger wires and if so what gauge?

Mike

You're still being moderated. Until you have more than 4 posts,your links won't work. Good questions! A friend has some electrical issues with his '59 Viking 60 bus,as well,and he's a journeyman electrician! Now if his bus was a 220/2-phase...L.O.L.

You're still being moderated. Until you have more than 4 posts,your links won't work. Good questions! A friend has some electrical issues with his '59 Viking 60 bus,as well,and he's a journeyman electrician! Now if his bus was a 220/2-phase...L.O.L. I'd think that your regulator,(built into alternator)?, would supply enough voltage to operate the essentials,without over-charging,or frying anything. But like Mikey pointed out-CHECK YOUR WIRING!! Replace any cracked/frayed wires! My '55 T.F. 6500,doesn't even have a fuse panel-YET! If your truck is "bare-bones",no radio,power accessories,then you may not have a fuse panel,either. Better to be safe than sorry. I'd at LEAST install an in-line fuse,between the alternator/battery.

the alternator will not put out 100 amps [or even 50] unless the battery and accessories combined ask for it, an original 54 generator would probably have been rated about 35 amps, so likely about 30 is tops a stock truck would ever ask for, although there can be situations just after starting there might be a momentary spike

if you want to be totally safe, replace the main output wire from the alt to the battery with 10 gauge, and yes, replace the ammeter with a volts meter or put a shunt on the ammeter so it doesn't take full current

Bill

I was under the impression that converting to a 12v would mean you needed smaller wires rather than larger wires (I'm rewiring my '37), what critical information did I miss?
Also am putting on an alternator but it was given to me and I'm not even sure its stats yet.

Rae, you never "need" smaller wires, the heavier gauge used with 6V works fine with 12V and provides a margin of safety, the heavier the wire, the less it will heat up under heavy loads - especially if you're going to an alternator, which will likely have higher amp capacity than the old 25-45 amp generators .... and note that the smaller the number, the heavier the wire

Bill

Bill -

My current wiring is a rotted-cloth mess, I was planning on replacing it with either 12g or 14g wire at the same time I am converting to 12v. I didn't know that certain lines would need to be larger( aka smaller numbered, thicker).

If I pick 12g, would I be able to use that for everything, then? Is that a good all-purpose gauge for this application?

The way I read this is, you plan to buy one roll of wire in one color and rewire everything. I hope I'm reading it wrong. If not, good luck getting it all connected to the right places and trouble shooting why it isn't working.

yeah, what Cletis says, you don't want to make everything the same color and gauge or you'll never be able to trouble shoot anything .... circuits are usually different gauges, from 16 to 10, depending on how much current they're expected to handle - assuming there's enough left of the originals, you should be able to tell which needs heavier or lighter, and most any auto or hardware store will have rolls 12' to 25' of at least half a dozen colors in different gauges - lighter gauge wire will be cheaper and fine for things like ignition and small lights, the more expensive heavier gauge is useful for the charging circuit, horn and headlights

Bill

There are charts on the web giving current carrying values for stranded copper wire sizes at various lengths. 6V wire is usually larger than 12V because the amp draw is twice that of 12V. Typically two sizes larger!
Note: when they calculate distance (length) they want you to include the ground return path thru the chassis for a total length number to use in the chart. Just double the wire length for that. Close enough for Gum'nt work.

Okay, I knew the circuits needed to be different colors, I guess I just missed the memo about needing different gauges. Thanks

IMHO, it would cheaper and faster to buy a ready made replacement harness from one of the many vendors. I don't think you can buy all the different wire needed cheaper than buying a ready made harness. The harness are available for: Under hood, interior, exterior, or something like that. So, only buy what you need. They even make an underhood harness for 12v conversions. Simple.

OK, I'm answering original poster. Getting confusing with several questioners. The Alt you have can be wired as one wire type by connecting to the spade terminals made for the connector and to the Big Pos lead. You need to read up on this, It really needs a sensing wire/bulb.
If your wiring is a rats nest or mostly in bad/old shape... rewire all. It's fun. I have done vendor kits and made my own. The make my own was same price as a cheap, no extras, low quantity circuit kit. Did it to get experience. I used Packard connectors and contacts and all good components. Old trucks have very little wiring and simple circuits. If your wiring is mostly good and a little bad, just buy wire and some crimped on components to spruce it up. Your wiring size and ammeter questions have been answered very nicely by others.

I bought an EZ Wiring harness and my alternator is a one-wire...next is fab an alternator bracket and buy a new gas tank. Finally warm enough in the Midwest to go outside again!