Ideally, yes, but that completely misses the point of programmable ESCs, which is that you can program current limits to get around exactly this kind of thing.
If you’re using a dumb, shuntless, non-programmable ESC like a Hobbywing or any other RC-derived thing, yes the over-rating holds true. But with VESCs and their derivatives, that is no longer necessarily the case.
While I agree that this does answer the question that OP asked, I submit to you that the OP is, in fact, asking the wrong question out of ignorance of how esk8 power systems work.
If the question is “How much power would I theoretically need to have zero bottlenecks between the cells and the motor?”, then that answer is great. But rarely if ever do most riders actually come anywhere near that level of power draw under any real-world conditions, and having that kind of potential explosive acceleration up near top speed is just a serious injury waiting to happen in the hands of anyone but a veteran rider.
Given that they’re a complete n00b on the forum with less than 20 minutes of read-time when I began my reply, and their questions, I’d say they are highly unlikely to need even half that level of power to have a blow-your-socks-off esk8 experience.
With 20A limit, vesc will only draw 960W from the battery. It would convert it to either high voltage low amp for speed or low voltage high amp for torque. This is how the battery amp is maxed out.
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Here’s when motor amps = batt amps. No bottleneck but… Not riding full speed on steep uphill all the time, arent’ya?
You can get the bemf v by dividing the motor rpm by the kv, and you get the winding resistance by mutiplying the vesc detected resistance by 2 since it detects single phase resistance, but you need the 2 phase resistance, and that resistance has to be in ohms not milliohms. Those formulas are for BLDC not FOC.
hence why i stated rc esc not VESC. VESCs are smart, you set the current limit and it will run upto that, a rc esc like (trackstar, quickrun, mamba, traxxas, hobbywing) are mostly dumb and will spin the motor to the desired speed amps be damned
i was just saying that for comparable dumb escs the parts must be overrated motor-battery to run properly. of course with smart/highly programmable escs like VESCs you can bottle neck it to prevent failure.
still don’t change the fact that if you got the motor amps and duty cycle you can work out the battery need for it.