Hi, I have two big old DC motors I got from a swap meet. The only sticker on them says "Nominal 30vdc." They only have two terminals so no wire size to go by. They work fine, no load, using a 30vdc 15A Buck/Boost speed controller.
They are about 4" diameter and 8" long. No idea what they came from but size matters. It has a 5/8" diameter shaft with 3/16" key-way, so guessing it is made for some serious torque.
I'd like to use one of them as a variable-speed fan motor for our swamp cooler which currently has a two-speed 1/3-hp AC motor.
I there some rule of thumb by which I can guesstimate the max current I can **safely** put into them to get 1/3-hp or 1/2-hp? This swamp came optioned with 1/3-hp or 1/2-hp but the 1/3-hp was all they had in stock at that time.
Or, do I wait for smoke and then back it off a few Amps? Joking? Too nice motors to destroy.