I am using 2 electric radiator fans from a 90's Camaro (and just about any other 90's GM car). Working on the wiring now and having a hard time finding information about ratings for relays, fuses, breakers etc. Most of the time, when you look for information on the internet, you will find so much information you can't really decipher accurate info. This is one of those cases. I have seen people post running current (per fan) of 5 to 50 amps. The 90's Camaro had a 25 amp fuse. I think both fans come on at the same time.
I'm not so concerned about running current. That I can measure. What concerns me is starting current. I have both fans on separate circuits with separate relays. Also the trigger for the fans is different so both fans don't power up at the same time. I don't have a scope to measure the starting current transient but I seem to recall that a loaded DC motor has a starting current transient ~5x running current.
So, my thinking is that the current spike would last less than 100ms and say that current is 50 amps. Would a transient current spike overload a relay, fuse or breaker?