Thread: Chevrolet Alt Charge rate

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Is 15v too high a charge rate for a sbc H E I.
Mine is charging at a firm 15v. I know that it requires 12v at the distributor for the car to start and run. The car has a Speedway alternator with about 300 miles on it and the module has gone belly up. Is this because of a bad module or is it due to the 15v overcharge rate?
Car has American Autowire harness with a Powermaster alternator in a 54 Chevy 210 sedan

yes, 15 is to much, normal range is between 13.8 and 14.2 volts. I had a similar issue with their alternator, turns out I had a weak ground and also the wire from the alternator has to go all the way to the battery. I had mine connected at the solenoid which was connected to the battery there. Why it made a difference? I don't know. But it had to run right to the battery.

Would a ceramic reducer like the 55 and 56 Chevy had in the wire going to the distributor work to reduce the voltage to 12 volts going to the H E I distributor or it reduce the voltage too much?

I suggest you have the alternator checked. I believe the problems is in the voltage regulator.

Originally Posted by onekarnut

Would a ceramic reducer like the 55 and 56 Chevy had in the wire going to the distributor work to reduce the voltage to 12 volts going to the H E I distributor or it reduce the voltage too much?

That wouldn't help your battery. You'll boil it dry and then go nowhere. I have the same exact alternator, and I thought it was a bad regulator too. BUT the manufacturer told me to run the alternator hot wire straight to the battery with no other connections and this fixed my problem(s) . as I said prior, I had originally had the alternator connected to the connection at the solenoid where the battery was also connected. This doesn't work. The alternator must go right to the battery terminal at the battery. Double check your wires, If the alternator is connected anyplace else, it will overcharge. It an easy thing to verify. If yours is wired ok, then we can go check other things, like pull the alternator and have it tested by a local shop. Mine would test fine at the generator shop, but back in the car it was overcharging!

Originally Posted by 34_40

That wouldn't help your battery. You'll boil it dry and then go nowhere. I have the same exact alternator, and I thought it was a bad regulator too. BUT the manufacturer told me to run the alternator hot wire straight to the battery with no other connections and this fixed my problem(s) . as I said prior, I had originally had the alternator connected to the connection at the solenoid where the battery was also connected. This doesn't work. The alternator must go right to the battery terminal at the battery. Double check your wires, If the alternator is connected anyplace else, it will overcharge. It an easy thing to verify. If yours is wired ok, then we can go check other things, like pull the alternator and have it tested by a local shop. Mine would test fine at the generator shop, but back in the car it was overcharging!

I will not dispute what you are saying but it seems odd as the battery cable at the solenoid and the connection at the battery are the same electrically,

Originally Posted by onekarnut

Would a ceramic reducer like the 55 and 56 Chevy had in the wire going to the distributor work to reduce the voltage to 12 volts going to the H E I distributor or it reduce the voltage too much?

Short answer is NO.

That was a Ballast Resistor on the old engines to drop the voltage after start to help not burn points. I believe it dropped the voltage to about 9V but could be wrong. Voltage to the coil came from the starter solenoid during crank, then through the Ballast Resistor with the key in "Run".

Check your alternator and your wiring like 34_40 suggests.

Originally Posted by NTFDAY

I will not dispute what you are saying but it seems odd as the battery cable at the solenoid and the connection at the battery are the same electrically,

And I thought the same thing. But, it didn't work that way. The connection has to be at the battery. Even more interesting, when I was assembling the systems, the alternator would work just fine. But as I added more electrical systems.. then things changed. By the time I got the cooling fan wired in. It was stuck on full charge!

The Powermaster is a great alternator. It’s straight-forward in its operation and seems to be a very solid unit. I have installed several of them over the years and never had issues with overcharging. My insides tell me that you have a grounding problem. Make sure you have a ground strap from the case of the alternator (Powermaster has a 5/16” – 18 tapped hole for this) to chassis of your car (see below).Also make sure your negative battery cable is well connected to bare metal on the engine block. I use star washers between the cable and the frame/block as they dig into the surface as they compress and help assure a good bond.

I also run a #6 wire (with crimped and soldered copper connectors) directly from the alternator to the battery – using a battery terminal connector with a lug designed to accept a connection.

Measure at the battery using a good digital meter – should be 12.6 – 13.4 volts

Regards,
Glenn