I'm wanting to upgrade the alternator on my 66 to a 100 amp unit. I'm currently running an older 63 amp GM alternator with built in regulator. It's works fine until I turn the A/C on and with the blower fan running, the volts drop to 12.5 and if I kick it up on high I'm down to 12. I don't run it that much but when I do, I don't want the battery going dead. I've read conflicting information regarding wire size for the charging wire. Some say 8 ga. while others say 10 ga. is fine if you're not running a lot of accessories which I'm not. I currently have a good 10 ga. wire running from the alternator to the horn relay, then from the relay to the battery. I would rather not have to pull the harness out and unwrap it to replace wires. Also, I have a set of the old style reproduction battery cables and the charging wire is made into the end. I don't want to change them either. Will the 10 ga. wire be enough or should I try an 80 or 90 amp alternator instead?
tider66
Joined
·
8,345 Posts
How long is the 10 gauge wire from the alternator to the horn relay?
Does your sense wire go to the horn relay?
Joined
·
8,345 Posts
Changing the wire from the horn relay ( the "charging" wire ) is not necessary. It will conduct plenty of current to charge your battery.
Changing the wire from the alternator to the horn relay, the 2' 10 gauge wire will make very little difference, since your sense wire is attached to the horn relay. The horn relay is the point to which you should attach all your various accessories, fans, pumps, etc. Changing from 10 gauge to 8 gauge will result in about 1 milliohm difference in wire resistance, less than 0.1 v difference at 60 amps.
The alternator upgrade by itself should be sufficient.
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
