I’m fairly new to efoils, but have built a few eskates and scooters and I’m in process of starting an esurf build. The topic of ESCs are ever present in every e-vehicle forum. The most common observation is that cheap ESCs can’t handle their rated max current, that you need to go 50% or even 25% of its rated max.
I came across this video, where this guy tests 2 ESCs (a castle 160HV and kosmik200) at full throttle, at 50% of their rated max current, the castle at 80a and kosmic at 100a: https://www.youtube.com/watch?v=z7jewAN1dTw&t=1s
They pretty much handle it with ease.
But then, he continues with a second test at partial throttle, at merely 25% of their rated max current, the castle at 40a and the kosmic at 50a:
It was a complete surprise to me, but both ESCs heated up far beyond their full throttle test and the castle 160HV actually failed and went into thermal shutdown protection.
A quick google led me to this post:
Basically, FETs don’t like to be turned off and act as resistors when they do. So at partial throttle due to the PWM of motor control, the FETs are turned off longer and thus act as resistors, and heat up and the more they heat up, the more they act as resistors, in a feedback loop.
This would explain why so many ESCs fail. That 400a Flier is probably capable of 400a at FULL throttle. But at partial throttle, even 100a will probably cause it to overheat. That 130a Seaking, sure full throttle at 130a, but at prolonged partial throttle, will probably overheat at only 25% of its rated max, 33a. Maybe this is old news to you guys, but it was an eye opener for me.
TLDR: partial throttle hammers your esc WAY more than full throttle. 25% or less of max rated current at partial throttle can kill it.