[Mike S]

After 20 tears my alternator on the race car bit the dust. I have a new 100 amp coming. I had the old one wired with switched B+ to terminal 2 and nothing on 1. I would have to rev it to 2000 to get it to start charging.
I was thinking of changing it to constant 12v to term 2 and use the switched 12v with a small bulb in series to term 1 so it would charge at idle.

How are you guys wiring alternators on your race cars?

[Scott65]

There is a wealth of information here:
http://www.madelectrical.com/electrical-tech.shtml
on charging systems and alternators specifically. And some nice parts to do the job.

[stellar]

Originally Posted by Mike S

After 20 tears my alternator on the race car bit the dust. I have a new 100 amp coming. I had the old one wired with switched B+ to terminal 2 and nothing on 1. I would have to rev it to 2000 to get it to start charging.
I was thinking of changing it to constant 12v to term 2 and use the switched 12v with a small bulb in series to term 1 so it would charge at idle.

How are you guys wiring alternators on your race cars?

That would work. I assume the way it was wired was to shut down the alt for the race giving you a little more horse power. With the #2 only it is going to act like a 1 wire alternator. Cutting off power to #2 will shut down the charging. If you connect the #1 and have the #2 connected it will charge at idle, but even if you break the circuit to #1 it will continue to charge so you have no way to make the alt inoperative.

[73LeMans]

I wired my mid 10 sec car with a "street" alternator (powermaster 140)because it sees more idle time and 40 mph then it does high RPM. Charges at idle, and no revs to turn it on.

Kinda on topic.....

If the alternator is still spinning and not charging, how much power does is really rob? I understand in a competitive environment, you need all the HP you can get, but wouldn't it then be better to remove the alternator and all its associated weight for better ets?

[Mike S]

Got the new alternator on. Bought a new 100 amp. Just wire battery voltage from the fuse block to number 2 term and of course battery voltage to the output. With the car running and fuel, water pump and fans off I get 14.3. With everything on I get 13.4. I used a DC amp meter and read 48 amps from the alternator. Does that sound right? Seems kind of high. Do you think I should change the 6 year old battery?

[Scott65]

Voltage seems low considering you're using ~half the output. What size pulley?

[77 TRASHCAN]

A 6 year old battery is OLD!!!