3G Alternator - I'm missing something

[Ford-f100-1972]

Hello everyone. I'm looking for some suggestion on a charging system problem. About 3 years ago I converted to a 3G Alternator on my '72's 302. Worked great until recently. Battery gave out so was replaced with a new 710CCA group 27 battery. Charged great at 13.8 volts and kept up with all of the lights, a/c and electric cooling fan.

The alternator gave up shortly after the battery. Replaced the old 3G with a reman unit. It would only charge up to about 12.3 volts regardless of rpms and would drop below 12 volts with the electric cooling fan running. Thinking i got a bad alternator, i took it back and upgraded to a brand new alternator.

Now I still have the same problem with the new alternator. 12.29 volts max and drops with a load. The alternator case is grounded directly to the battery and the engine ground is making a solid connection. The alternator connections are clean and the connectors are in good condition. The battery tests at 12.51 volts a few.minutes after shutting down the engine with 715 CCA after it cools down completely.

What am I missing here? Any suggestions will be appreciated.

[yellercat]

Same pulley size (diameter)?

[390FE1972]

My truck has a 60 amp alternator, so I don't have any experience with the 3G alternator, but here are some threads with very good info that you might want to look thru to see if they help:

http://www.fordification.com/forum/view ... =8&t=13062
http://www.fordification.com/forum/view ... =8&t=62271
http://www.fordification.com/forum/view ... =8&t=70371
http://www.fordification.com/forum/view ... =8&t=65312

Let us know what the fix is

Regards

[Ford-f100-1972]

Thanks for the information! I went ahead and replaced.all of the cables and everything is good now. 14.5 volts at the battery. Must have been a week area in one of the cables. I appreciate the help! :thup

As for the pulley, I had to change the serpentine pulley out on the new alternator to my original v pulley. Both are roughly the same size.