You can make a dual  alternator / motor that is essentially cogging
free - even with iron in rotor and stator..

If you use "ironless" construction for the stator you can get
essentially zero cogging as of right. This is realistically only
possible with rare earth magnets. You can get alternator efficiencies
over 90%.

Making a motor regenerate is not overly hard. But for best results
you'd want to smps convert it to the appropriate energy for battery
storage.

Battery charge rate is a significant consideration. No matter how
little power you expend when running , you want to be able to reduce
velocity at a "good" rate so power delivered is high. If you were
using a say 12V 7AH AH battery then even at say 10C charge you are
allowed 70 A x 12 V =3D 840 Watt =3D slightly over a  HP. Consider how
rapidly 800 odd Watts would accelerate you and decide if you want to
decelerate no faster than that under braking.
I didn't think so.
Oh well.
(Some might say).

Lead acid is not too keen at very high charge rates although, properly
done it can tolerate higher curr4ents than usually claimed. LiFePO4 is
far more tolerant but so far is very very expensive compared. Overall
lifetime cost of ownership is lower than any other common battery but
capital cost is mny times larger.



       Russell
--=20
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