Without getting too deeply into the tech, this Evelo video explains some of the issues.
Some systems are better than others and the subject is certainly debatable but I tend to look at it from a real world perspective.
I watched the video and I have a few things that I question.
This is my old e-bike with regenerative braking,..
In the video he said that it doesn't have a free wheeling mechanism, but you don't need one.
If the the regeneration isn't turned on, then the wheel spins freely.
My regeneration turns on when either brake switch is activated or my ebike goes over 25 kph.
If you are riding a non regenerating ebike, going downhill, you can try to conserve energy by going as fast as possible and use your built up momentum to carry you further past the bottom of the hill so you don't need to power up the motor as soon.
But, if your speed increases from say 15 mph to 30 mph, the wind resistance is at least 4 times as great, (and 9 times as great if you triple your speed)
If you have a regenerating ebike, you could use regeneration to maintain the 15 mph so you're not wasting all that energy pushing you through the wind. You could probably regain 2-10 times more energy than speeding up and trying to harness momentum.
And if you keep pedaling during the decent, you get even more energy put back into the battery.
Also, I go a lot slower downhill because I toggle the regen on and try to harvest as much power as I can.
That all makes sense to me.
That's what I do.
One thing mentioned in the video was that regenerating/charging creates a significant amount of heat in the battery but I question how significant that is, and I would think Grin would have taken that into consideration in their design.
I'm sure it won't overcharge a battery (that would be stupidly dangerous!!), and they probably limit the recharge rate on a battery that is close to fully charged ?
My understanding is that a lithium battery that is closer to empty, can take a huge charge current without getting as hot as the same battery closer to fully charged.
@gromike said that he generated 600 Watts briefly. 600 Watts into a 48v battery is 12.5 amps.
That may very well be OK as long as it's not for extended periods of time.
I certainly wouldn't want to charge my battery at home at that rate.
As far as generating electricity (the reason I went with a DD motor), when I put the bike on a training stand, pedaling on regen was so difficult as to be almost impossible. So my bicycle emergency generator probably needs adjustable levels, as opposed to just toggling regen on.
You need a KT controller/display.
It has 5 levels of regeneration,..
It looks like Grin has taken care of the "damaged motor shaft" issue with your torque arm placement.
I'm pretty sure that you could pedal the bike at the "Bad energy recovery" setting?
Just keep the wheel spinning as fast as you can (not your cadence).
Hub motors aren't very efficient at low RPMS.
Or, better yet, make a variable regeneration throttle.
All that the 5 different KT regeneration settings do is adjust the voltage going to the motor in the reverse of power mode.
The higher the voltage the greater the regeneration output.
Why not a double twist throttle?
Twist it one way the ebike accelerates proportionally. Twist it the other way and the bike brakes/regenerates proportionally.
Come On Grin !!??
Gimme a throttle and controller that I can work with !!
And make sure that the motor is on the rear wheel.
You don't want to go over the handlebars.
Having steering and regular braking on the front wheel is enough.
Skidding out the front wheel is a lot worse than skidding the rear wheel.
I had a geared hub screwdriver in the 90's. It was a ten dollar piece of crap because it would regenerate instead of locking the axle.
It used two AA batteries to power a 0.00001 Watt motor (or however many horsies a tiny 3v motor can deliver).
When I hit the power to unscrew a tight screw, it wasn't powerful enough to undo the screw, and when I twisted the handle, the handle just rotated so I had to use a normal screwdriver to at least loosen the screw, but that pretty much defeated the purpose of an electric screwdriver.
I bought a better one that had more power, and if it wasn't powerful enough to undo a screw, I could twist the handle and the gears would binde so I could loosen it, then hit the power to undo the rest.
So I get why they say you can't regenerate a geared hub motor, but there are ways around it.
Apparently Grin is working on a geared hub regenerating motor where the armature is spinning 5 times faster.
Now all they need is a proper throttle with reverse twist to go along with it.
Just ditch the rear brake lever and work the rear brake with a variable regenerating reverse twist throttle.
