The Aptera Forum
The BMW i3 has done this for 8 years. It is called one pedal driving. The regenerative braking is very strong and takes some getting used to. If you let off the pedal, the car doesn't coast like on other EV's. To coast, one must keep the pedal at an intermediate level. But after learning the system, it is much more pleasurable than conventional systems. The only time the hydraulic brakes are required is when you need more braking than the regen can offer such as when you need to slow down rapidly. Otherwise with normal unobstructed driving, when hardly touches the brake pedal. The only time I really need the hydraulic brakes is when I am stopped, say at a traffic light and there is a slight downhill grade of even a few degrees, the car will creep forward. That doesn't happen if stopped at an upgrade. One of our BMW forum member was able to get 175,000 miles before replacing his brake pads. Kind of like hypermiling on the brakes.
I've ridden electric motorcycles where the brakes were hardly needed except of course for emergency stopping.
It maybe possible, depending on motor configuration and controller configuration. This recent interview with head engineer of Aptera motors, Nathan Armstrong said that motor controller technology can get to the point you describe. I forget when the video he says this https://youtu.be/vfihjJR6zXk
Okay, so a minimal electric parking brake, maybe rear-wheel-only, could be used in place of "park", to hold the car stopped on a hill without wasting energy, then release as soon as you hit the go pedal. That would still eliminate a lot of complexity, cost, & unsprung, rotational weight.
It is possible but very inefficient to use AC motors to hold a fixed position as you need to keep the coils energized back and forth in forward and reverse directions. So you would want a mechanical brake for low speed, stopping, and definitely for parking. They possibly could make a more complicated drive motor with some intrinsic holding torque (like a stepper motor), but that would add weight and compromise performance. The mechanical brake could be much smaller and you probably don't need a full hydraulic system. I don't know what the legal requirements are for autocycles.
I thank you all for your concision. I cannot wait for deliveery.
Yes unless you really needed to stop fast!
@OceanDragon 1-Pedal driving is a separate issue.
The left pedal of any EV activates regen for all but emergency braking, & sometimes activates friction brakes below a certain very low speed. For example, my 500e friction brakes come on during any braking below about 6mph. But in normal driving of an eGolf, even on it's lowest 1-pedal regen setting, it still comes to a complete stop without friction brakes. It uses only the regen which is activated by the left pedal. I believe Teslas do the same.
All that 1-pedal driving does is make lifting the right pedal perform the same function as pressing the left pedal, during normal driving.
As for eliminating all the cost, complexity, & rotating unsprung weight, of the entire hydraulic/friction system as Nathan said is possible: Since the motors have enough power for full-traction acceleration (burnouts) they ought to also be able to provide full-traction braking. & I wonder if when fully stopped for more than a few seconds the computer could just engage the park pawls in order to prevent power drain.
I don't think the Elaphe in-wheel motors have parking pawls, so they would need at least an electric parking brake. Only some EV's have parking pawls in their gear box. The Tesla Model 3 omitted parking pawls to save money, for example.