The motor and battery current is in most cases not controlled directly by the ESC, except the VESC and some EV controllers. So the current (at full throttle) is dependent on the battery voltage and the load of the motor and its Kv. So using a smaller ESC with less Ampere rating will only lead to a burnt ESC. Maybe it will protect itself from Overtemperature in some way, but all the burnt ESC in the RC-world and also here, show this protection is insufficient.
To reduce the motor current you can do mainly these things:
- Choose a prop with less pitch and/or diameter
- Reduce the voltage of batteries
- Choose a motor with less Kv
- Choose a higher reduction gear
- Reduce the applied throttle signal (Dual rate it was called in former times, you can do this in your transmitter by the settings, e.g the enertion controller allows to half the max throttle, called beginners mode)
- Choose a ESC which has shunts or other measurement for the motor phase current to limit it.
Every solution has its pro and cons, and most times a combination will give the best results. E.g. if you go for 6. you might additionally choose one of the others to reduce overall motor current to increase the overall efficiency.
I have done so after burning a too small motor with a well cooled YEP120A HV watercooled ESC, which failed itself when the watercooling was not working anymore. Afterwards i chose a larger motor (6374 -> 6384) which burnt my VESC because i increased the temperature limit settings without having a proper cooling.
So next step is a better cooling for VESC in combination with a smaller prop (175mm -> 140mm) and a motor with less Kv (6384 130Kv -> 6384PG 100Kv). Direct drive outrunner with direct water cooling
So the misunderstanding here is that the ESC will limit the motor phase and/or battery current. The currents specified are a rating what the ESC can withstand without damage, often limited in time and always presumed you have a very good cooling.
So typically you end up with overdimensioned ESC, motor, batteries and cables to get the performance you want, burning some of the components from time to time, especially when the conditions change. This is intended by the RC industry, so they can earn more money. It could be solved easily with a phase current limitation which is matched to the motor and battery capabilities. The VESC provides all these features, but has the drawback that the original cooling is very bad. There are better cooled and designed VESC available, but the cost to performance ratio goes through the ceiling. You can try yourself to improve the cooling by water or air.