One for the clever people who know about controllers...

stargazer30

Pedelecer
Sep 29, 2020
34
15
Does anyone know if there is a controller out there that can be setup like the Gtech controller?

The Gtech BB sensor and controller is pretty smart. It varies the current and max speed by cadence. When you first pedal it gives full power but as the pedals speed up the power drops off. The power is cut when a certain cadence rpm is reached or the actual speed of the hub motor hits about 13.5mph, whichever happens first.

On a geared bike like my Boardman MTX it works really well as you can use the gears to set the assist. Its a better system than the on or off PAS system on my Ezego which turns on the power until you hit the set speed for the assist level.

I read that the KT controller has current control but the implementation seems a bit basic, like its a fixed current set by assist level? If I understand correctly , its not smart enough to do what the Gtech controller does, apply max current at low RPM and reduce it is as you speed up?

Ideally I'd like to fit a bigger battery and controller to my Boardman to get the top speed and range up a little but I don't want to loose the variable assist.
 

vfr400

Esteemed Pedelecer
Jun 12, 2011
9,822
3,950
Basildon
Does anyone know if there is a controller out there that can be setup like the Gtech controller?

The Gtech BB sensor and controller is pretty smart. It varies the current and max speed by cadence. When you first pedal it gives full power but as the pedals speed up the power drops off. The power is cut when a certain cadence rpm is reached or the actual speed of the hub motor hits about 13.5mph, whichever happens first.

On a geared bike like my Boardman MTX it works really well as you can use the gears to set the assist. Its a better system than the on or off PAS system on my Ezego which turns on the power until you hit the set speed for the assist level.

I read that the KT controller has current control but the implementation seems a bit basic, like its a fixed current set by assist level? If I understand correctly , its not smart enough to do what the Gtech controller does, apply max current at low RPM and reduce it is as you speed up?

Ideally I'd like to fit a bigger battery and controller to my Boardman to get the top speed and range up a little but I don't want to loose the variable assist.
The Gtech doesn't do anything clever. There are no gears so pedal speed and wheel speed are in direct proportion. It's the wheel speed that cuts the current, not the controller.

The controller only allows current. At low speed, you'll get whatever the controller allows, but at some speed, the back emf from the motor starts cutting the current in proportion to speed until the current is zero at the motor's maximum RPM.

Without a controller, the motor would draw enough current to burn itself out at zero RPM. That current ramps down in a straight line to zero at max RPM. Let's say that the motor can do 20 mph and it would draw 40A at zero RPM. Without the controller, it would draw 20A at 10 MPH, 10A at 15 MPH and 5A at 17.5 MPH. If a 15A controller was set to maximum, it regulate the current at 15A until 12.5 MPH. After that, the motor speed would be controlling the current.

I've never heard anybody complain about KT controllers when set to current control. You're worrying about nothing.

It's not clever to know about controllers. It only takes a short while to study them and learn. Remember, just about every Chinaman that was unfortunate to be born with a very low IQ, still managed to figure out how to speak Chinese. Controllers are not nearly as difficult as the Chinese language.
 

stargazer30

Pedelecer
Sep 29, 2020
34
15
The Gtech doesn't do anything clever. There are no gears so pedal speed and wheel speed are in direct proportion. It's the wheel speed that cuts the current, not the controller.

The controller only allows current. At low speed, you'll get whatever the controller allows, but at some speed, the back emf from the motor starts cutting the current in proportion to speed until the current is zero at the motor's maximum RPM.

Without a controller, the motor would draw enough current to burn itself out at zero RPM. That current ramps down in a straight line to zero at max RPM. Let's say that the motor can do 20 mph and it would draw 40A at zero RPM. Without the controller, it would draw 20A at 10 MPH, 10A at 15 MPH and 5A at 17.5 MPH. If a 15A controller was set to maximum, it regulate the current at 15A until 12.5 MPH. After that, the motor speed would be controlling the current.

I've never heard anybody complain about KT controllers when set to current control. You're worrying about nothing.

It's not clever to know about controllers. It only takes a short while to study them and learn. Remember, just about every Chinaman that was unfortunate to be born with a very low IQ, still managed to figure out how to speak Chinese. Controllers are not nearly as difficult as the Chinese language.
I have retro fitted a gtech v1 controller and bb speed sensor to a geared boardman mtx bike. Pedal and speed are not in direct proportion. I am sure the gtech setup measures cadence speed as on my bike the assist cuts off at a different speed depending on the gear it’s in. Depending on gear it will cut off at anything from 9mph to nearly 14mph.

I can’t be sure but I think the current is variable too. This is just my butt Dyno comparing it to my other hub ebike.
 

Nealh

Esteemed Pedelecer
Aug 7, 2014
16,938
6,612
59
West Sx RH
The only way to know if the current is variable is to wire in ammeter and watch the current draw, most current controllers to some degree has variable current, as speed rises back emf will reduce current. It isn't smart, just natural characteristic.
I see this with my current control controllers via the watt's displayed as they back off nearer the cut off.