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Discussion Starter · #1 ·
I am having a problem maintaining a constant output voltage from my alternator after the car warms up.

Car is a 72 nova, all 12v system, running a NAPA rebuilt 94A 12SI alternator. I have an electric water pump, electric fuel pump, and electric fan as add ons, and the ignition is a simple HEI.

A month or so ago I got distracted after a pass and left the fan and pump on a little too long and drained the battery. Got a jump and ran the car for a few minutes to charge enough to get back in the staging lanes. Made a pass and the alternator shorted out. The fusible link to the starter burned out as well. I looked over everything else and replaced the alternator and link, thought I was good to go.

Now the problem maintaining a steady voltage and the alternator gets way too hot, you could cook an egg or two on it.

On a cold system I have 14.48v with no accessories, 14.28v with water pump and fuel pump only, 14.09v with fan on, all at the battery. I'd have to check again, but voltage drop from alternator to battery was .1 or .01v. After the car warms up the voltage drops to 13.6v with fuel and water, and 13.01v with fuel, water and fan. And performance drops significantly too from 11.40/117 to 11.60/114.

Do you think it is just an alternator or is there a bigger problem going on? Thanks for any and all advice.
 

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Alternator needs to be checked for sure, it sounds like it is not working properly. Does it use the two spade connectors 9regulator) in the side of it, or is it a one wire? Have you have the battery tested?
 

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Discussion Starter · #3 ·
The alternator I use has a two spade connector. The alternator has a lifetime warranty so I exchanged it at Napa tonight. After swapping alternators, engine running and the voltage at the battery is 14.28v running the waterpump and fuel pump. Add the fan and it drops to 13.89v. I didn't have the time to take a short spin and get everything up to temperature yet to see if I still have a voltage drop like I did before.

The battery is an Excide that is 3 years old. I haven't had it tested.
 
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