1966 c10 alternator: How many amps?

[bloo]

How many amps was the stock OE alternator on a 1966 c10?

Thanks.

[rpmerf]

OE would had been an externally regulated generator. Seeing on RockAuto 42 or 61 amps. The 42 is an AC Delco, the 61 is a Remy. Not sure if the 61 is stock or an upgraded reman.

[bloo]

Thanks. I am trying to figure out if I have too much alternator for the wiring.

The one on the truck now is a stock type, with an external regulator. I haven't measured how many amps it can do yet, but I will soon. I was just wondering how big the one was GM put on it back in the day. This one seems to be getting the charge wiring a little hot.

[Vincenthdfan]

Originally Posted by bloo

Thanks. I am trying to figure out if I have too much alternator for the wiring.

The one on the truck now is a stock type, with an external regulator. I haven't measured how many amps it can do yet, but I will soon. I was just wondering how big the one was GM put on it back in the day. This one seems to be getting the charge wiring a little hot.

I just got a conversion wiring segment/harness from American Wiring to convert my 62 from a Generator to an Alternator.

They recommended no more than 62 Amps for factory truck wiring...I'm installing a 63 amp, figure that's close enough (hopefully!).

[rpmerf]

If you are able to find a part number, you could reference that to what amp generator it is.

You can look up amp / wire gauge charts. 1970 with AC was factory 63 amp generator and 12 gauge wire. I now have a 78 amp alternator and 8 gauge wire.

[bloo]

So the factory used 12 gauge with 63 amps? Good to know. Thanks!

[vince1]

I am under the impression that the Delco alternator with the external regulator is 42 amps. I did find the output wire a little burnt right at the alternator. When I changed to the 10si 63? amp with internal regulator I also changed the wire from #12? to #8, from the alternator to the junction block (horn relay?) and across to the battery. This would also be heavy enough if changing to a CS130 105 amp as supplied on an 89 Pontiac Safari.

[MikeN]

Interesting question, I was under the impression that the original alternators were really low amps, like 29 or maybe 39?

[MikeN]

NAPA online lists the stock alternator for a 66 C10 w/o A/C as either a 37-amp or 42-amp alternator.

[The Rocknrod]

In the factory historical manual you can download from GM the C10 section shows(there are two pictures shown here, smaller print for standard and larger print for options):

[franken]

Originally Posted by bloo

Thanks. I am trying to figure out if I have too much alternator for the wiring.

The alternator doesn't put out the rated current. It puts out what the load demands. That said, newer alts may have a higher voltage setting and therefore deliver more power.
I'd tend to look at the condition of the wiring if something is getting hot.

[vince1]

I think the charging voltage across the board for most alternators is about 14 to 14 1/2. I don't know what happens with a lower rated amp alternator. Does the voltage just drop off when it can't keep up to demand?

[bloo]

Originally Posted by The Rocknrod

In the factory historical manual you can download from GM the C10 section shows(there are two pictures shown here, smaller print for standard and larger print for options):

Thanks! That is exactly what I was looking for!

[bloo]

Originally Posted by vince1

I think the charging voltage across the board for most alternators is about 14 to 14 1/2. I don't know what happens with a lower rated amp alternator. Does the voltage just drop off when it can't keep up to demand?

Yes. If the alternator can keep up, the whole truck runs at the regulator voltage (probably about 14.7 volts). Any leftover current capacity (amps) goes to charge the battery. The battery takes what it wants. If the battery is low it might take all the leftover current available, but usually not.

When the alternator can't keep up, the voltage in the truck will drop fairly quickly to the natural voltage of a 12v battery (about 12.6 volts). The voltage will continue to drop as the battery discharges. Eventually the battery would go dead if this went on for a long time, but usually it doesn't.

When the alternator catches back up, the voltage will go back up to 14.7 or so, usually instantly, but if the battery is about half discharged it might draw all the current available for a short period of time. In that case the voltage would head back up to 14.7 a little slower as the battery charges.

Even a 37 amp would keep up with most trucks just fine. Huge 100+ amp alternators are unnecessary 99 percent of the time. Some people want them. Nothing wrong with that, but the wire has to be big enough, because it could melt, and it won't happen until some cold morning when the battery is half dead.