ESC Motor Limits - Why?
 

Kinda of a newbie question from a non-newbie here. What is the reasoning behind motor limits on ESCs? EG: If I've got an ESC with a 5.5T limit, but want to run a 3.5T motor, what are the dangers? If it's heating, could a very powerful fan deal with it? If the motor is undergeared so it's allowed to spin up easily and never stress itself on the torque side of the equation, would this make it work?

What are the guidelines? How much wiggle room is there?

The limiting factor is the MOSFETs: they have a maximum current rating, maximum power rating, and limited Safe Operating Area (SOA). (The SOA limit involves both power and time.) A fan can help with the power rating and SOA.

The motor limit is dependent on the timing, gearing, and load-- for instance, a FWD car draws less current when the wheels spin. It is possible to blow an ESC even with a motor with more turns than the ESC rating.

My advice is: don't push it. Get an ESC that is extra hairy, so you have a safety margin.

Thanks, as always, Howard. I've got an ESC that can handle a 3.5, but, due to my unwavering dedication to laziness, didn't want to swap the ESCs between cars. If I do this, it'll be going in a car with an fdr of 5.5-6 and a weight around 1000gr. Pretty light and rev happy.

Thanks again.