alt Hacker News> If you have a lighter more efficient motor you need a smaller battery for the same range
Nitpick: You can have a lighter motor, but you're never going to have a significantly more efficient motor because existing EV motor systems are already 95% efficient or better. The electric motor is an old and refined technology.
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Qwertious • last Monday at 7:50 PM
Suppose you go from a 95% efficient electric motor to a 99% efficient motor. How much more efficient is it? You might say 1.04x (or actually 99/95 efficient). Except, that's not the whole story - electric motors need cooling, and you've just dropped the heat output five-fold (going from 5% heat to 1% heat). Lower heat output means less venting needed and thus better aerodynamics.
I'm not an expert - but the axial flux design while old is been largely ignored due to manufacturing problems that have now been overcome ( so most of the dev has been on the radial flux variety ).
And apparently axial flux motors have shorter magnetic flux paths which reduces losses.
ie the efficiency gain is due to the switch from radial to axial flux - not some incremental gain on radial flux.
Having said that the efficiency gains are relatively small - 1-2%.
However again there is a compounding effect, in that the reduction of loss of energy as heat, leads to requiring less cooling - and/or the motor is able to operate a full efficiency over a wider power output range ( as heating the copper increases the electrical resistance ).
https://www.stanfordmagnets.com/advantages-and-disadvantages...