Alternator question ?

[Highbanked Hauler]

  Time to replace the old one in my sled which was stock and other than an electric pusher fan  and electronic ignition nothing else has been added. WHAT is the best amperage to get as I see Summit has 90, 130 and 160 I think it was  Thanks..

[Nacho-RT74]

how much the electric fan sucks out ?. That will be the key. 130 could be quite enough. Actually even 100 amps ( tuff stuff has those, and Summit sell them ). 90 could be a bit on the tight line if you have A/C and drive daily specially at nights. Wipers sucks a lot too, but that could be a problem being a driver and finding lot of rain.

More than the max output, if you get specs at idle will be better. something like 60-65 amps at 2K Rpms at alt should be enough. That would be close to 1050 engine RPMs. So at iddle should be on 55-58 rate.

( electronic ignition is not a problem )

[Highbanked Hauler]

how much the electric fan sucks out ?. That will be the key. 130 could be quite enough. Actually even 100 amps ( tuff stuff has those, and Summit sell them ). 90 could be a bit on the tight line if you have A/C and drive daily specially at nights. Wipers sucks a lot too, but that could be a problem being a driver and finding lot of rain.

More than the max output, if you get specs at idle will be better. something like 60-65 amps at 2K Rpms at alt should be enough. That would be close to 1050 engine RPMs. So at iddle should be on 55-58 rate.

( electronic ignition is not a problem )

   No AC and not likely at night. The fan has a relay in line so that would be OK wouldn't it ?

[Nacho-RT74]

The relay only helps on get the switch saved from loads or work as a switch by itself with a trigger signal from some sender. But would be interesting to know the load the fan sucks. They usually are on 8-12 amps rate.

If you still have ammeter, please source it from alt stud

[b5blue]

I'm liking these: https://www.qualitypowerauto.com/pages/ChryslerMegaAmp.php    Fan could be up around 30amp while spooling up.

[Nacho-RT74]

I don't think 30 amps ever! what's the wire gauge for it ?

[John_Kunkel]

The instructions with CCI fans says:

"These fans draw 60+ amps on initial startup and have an operating amperage draw of 16-22 amps. Due to the high amperage these fans pull on initial startup, we highly recommend using 70 amp fan relays"

[b5blue]

Yup Rainbow's low/high (2 wires for high so I assume 2 windings.) about the same.