Cadence sensor driven rear hubs.. adding a torque sensor to existing systems?

[PCeBiker]

If your battery is a 48V 25Ah with these cells it is probably a 13S 5P configuration
5 cells in parallel provide 5 x 4.9Ah = 24.5Ah
These in series 13 times create 13 x 3.6V = 46.8 Volts (manufacturer often use 3.7V for their calculations... hence the 48V)

If so, then its max safe charge current would be 2.45 A x 5 = 12.25 Amps
With possibly a peak charge for brief moments of 4.9 x 5 = 24.5 Amp

So with being said, your 8000 Watt e-bike should be able to safely produce roughly 4000 Watts of regenerative power?

The specs do say though "(not for cycle life)" and the standard charge rate is half the maximum.

My battery came with a 4 amp charger but I only charge it at 2 amps to help increase my cycle life.
I don't mind waiting for it to charge.

 

[PCeBiker]

I read somewhere that regen recovery with general traffic use is only 5-7% with all the associated losses. I do not know if this is accurate, but seems in range.

I was considering a GRIN regeneration motor, but even the guy from GRIN said that the most you can expect is around 10% even in mountainous terrain.

The area around me is almost completely flat, and I can ride for more than half an hour without ever using the brakes.

I may actually even lose some range with a regenerating motor?

 

[scrambler]

So with being said, your 8000 Watt e-bike should be able to safely produce roughly 4000 Watts of regenerative power?

The specs do say though "(not for cycle life)" and the standard charge rate is half the maximum.

My battery came with a 4 amp charger but I only charge it at 2 amps to help increase my cycle life.
I don't mind waiting for it to charge.

On yours I would not regen at more than 2.45A /cell or 12.25A x 48 = 590W

My battery is a 12S12P but with older 18650 cells that only do 1.7A charge, so I am limiting my regen to 25 battery Amps which is max 1200W

BUT, on my bike, The controller Can modulate the voltage to get more Motor Phase amps for more torque.
For example, My battery has a max Amp of 15A/cell or 180A for the 12P pack, and a Nominal voltage of 43V for the 12 S configuration.
That means the battery can push a nominal 8kW. BUT, at lower speed, the controller can push 360 Motor phase amps by reducing the Voltage to 21.5V.

And so the same thing applies to regen, I can tell the controller it can go as high as 50 Phase Amps of regen, as long as it does exceed the 1200W of power to the battery. At low speed when the Motor voltage is lower I can actually get much stronger regen torque at the rear wheel that way.

This is actually plenty, and I would not want any more regen braking power. I tried and it was just too strong.

 

[harryS]

Getting back to the original question about adding a T/S to a cadence bike. This discussion on another forum is an example of getting too deep into the details to make an add-onT/S work. Just buy a T/S system if that's what you want.

Delayed overshoot in torque assist after pause in pedalling (Sempu T2 + Cycle Analyst)

Hi, I have been running a GMAC + Phaserunner + Cycle Analyst (all 3 from Grin) + Sempu T2 torque sensor (Aliexpress) for a few years now and while the overall performance is generally good, I have been frustated with the torque assist. The main issue is a delayed response of the motor after a...

endless-sphere.com

 

[Slaphappygamer]

Piggybacking in the above, there is even a 3 part video series. This one, below, explains what it would involve to install a torque sensor on a rad bike.