Need help on adding a throttle to an REI Co-op 1.1 bike

[Bob.A]

My step daughter bought one of these REI bikes last year when the went on sale. She really likes the bike except for one thing. She has MS and the bike does not have a throttle, it's a class 1. She needs the throttle to help start off from a stop so I offered to see what I can do with it.

I've built 3 ebikes so far for myself, all recumbents with mid drive motors. This bike uses a 36v 350w bafang hub motor along with hydraulic brakes. It's a decent bike considering she paid 700 for it when they went on sale. I picked it up yesterday and started some exploratory surgery on it today. I got the controller out from its tight little hiding spot, it's a bafang branded controller that I cant find much information on .

I'm not looking to spend lots of money upgrading a 700 dollar dept store ebike. It's not a bad bike considering. Has hydraulic brakes and a name brand hub motor. As for the torque sensor, that can just stay where it is, I can add an external PAS sensor. I asked her last summer if she knew what she had and she didnt have a clue.

What I'm looking for is some type of controller I can swap in for the existing box that will work with the existing bafang motor without any problems. Current controller is rated for 15a at 36v. If I have to start cuttin and splicin I can do that, though it's not the first choice. If I can fit it in the existing space, thats fine too, otherwise I figure out a spot to mount it outside. I'll also need a matching display and the new PAS and throttle.

I do wonder if it is worth opening up the OEM box to see if there may be some terminals or unused connection for a throttle switch that was not used to keep it as a class 1. Sorta like the Tongsheng mid drive controllers that could be hacked to hook up a throttle.

The bafang hub motor:

The controller out of its hidey hole:

9 pin connector to the motor:

The existing connections. The one with the two larger terminals is battery. I think the lavender is the torque sensor and the last is the display and brakes

 

[harryS]

I'm partial to KT controllers for hub motors. I also have two TSDZ2 mid drives and one Bafang BBS02.

About $100 to get everything and replace the bafang electronics. If you hunt around, you can get a 17A KT sinewave controller and an LCD display for maybe $80, but it's worth $24-30 not to have to splice connectors for PAS sensor and brakes, The KT 9 pin motor cable is plug compatible with bafang motors. Have converted three bafang hub motors. They always have built-in speed sensors.

 

[indianajo]

There are a lot of throttle only controllers on ebay that you can drive the bafang motor with. Most do not have the center pin for temperature. Just 8 pins. You will not find IMHO those sensor connectors and the scooter controllers do not come with a display. They require a "door switch" which turns the controller on or off. I use a toggle switch in a pill bottle under the seat, to connect "alarm power" to "door switch". Alarm power is a red connector with red & black wires usually. If you don't turn the door switch off when you stop the controller runs the battery down a couple of volts every day.
Those sensor and brake connectors are weird. If the brake handles short when you pull them, you could connect the wires from them to the 2 pin brake connectors on the scooter controller. Grey/black usually. May not find the mating connector, you may have to cut the connectors off. Or you could buy brake handles with the right connectors.
Don't go wild on the amp rating, I've burned some 350 w motors with a 25 A controller.
Scooter controllers tend to rotate backwards from ebike, so you may need to swap colors on two phase wires and a couple of hall sensor wires. Or short the "learn" connectors on white wires briefly every time you turn the power on.
I ride without PAS pickup. PAS1 was too fast for most pavement anyway. And being whacked in the back of the leg when I spun the pedals backwards to get a good start got really annoying. Controller powered up in PAS1, had to be turned down to zero. Display shorted out in the rain first year anyway. No PAS sensor, no adjusting the levels with the display.

 

[Bob.A]

Thanks for the quick replies.

I've found one kit on Amazon that I think might do the trick. Amazon link It has the controller, pas sensor, display, I looked again last night at the bike and the output cable. The only existing connections I have to use are the output to the motor and the DC in and that is just 2 wire. There are no brake switch inputs since it was a torque sensor crank and as long as you stop pedaling, the motor stops instantly. I'd rather order off Amazon than Aliexpress, If I have problems, returns should be much easier.

I'm thinking I can hook this up for testing first without cutting any of the existing wiring and see it work. I gotta keep in mind that I'm not the end user and that it has to be pretty seamless or I'll hear about it for a long time. If it doesn't work well enough, I want to be able to put it back as it was and tell her I gave it a good try. Lots of these offerings seem to have the same parts, the controller in this case has speed misspelled as Speet and that pops up on more than a few I've seen.

 

[harryS]

Thanks for the quick replies.

I've found one kit on Amazon that I think might do the trick. Amazon link

It will run the bike, like any other kit, Will it feel right?

I would think that the original REI, if it was torque sensor feels as natural as an ebike can feel, as far as power delivery, The cadence sensor systems use pedal motion like an on/off switch, but the more popular ones can do some tricks to deliver power with a more natural feel, After doing a few ebike conversions, I decided I liked the feel of the KT controllers. I've found in other ebike build forums, that guys who do it for money feel the same way, There reallly are some kits out there with awful PAS.

WHat motors on your recumbents?

 

[Bob.A]

Motor is a Bafang 350w 36v. The controller on Amazon is a sine wave type, from what I understand it should be pretty smooth. I want to get something that has the controller and at least a display and PAS sensor included so I know they should all work together from the gitgo.

 

[PCeBiker]

BTER E-Bike Motor Controller Kit, 36V48V 500W Electric Bike Motor Speed Controller with LCD Display, DIY E-Bike Conversion Kit for KT, for Electric Bicycle, Scooter, Electric Skateboard https://a.co/d/7qtgrJ8


This kit comes with brake levels with switches for cable type brakes, and sleeker looking waterproof connectors..

Amazon.com

 

[PCeBiker]

The controller on Amazon is a sine wave type, from what I understand it should be pretty smooth.

You can program the power delivery of the KT controller with the KT display to suit the riders needs.

I put a KT Display/Controller on my almost new ebike because the power delivery sucked.

AliExpress has a lot more options with better prices. (at least here in Canada.)

 

[PCeBiker]

This stuff on Amazon would work,..

Controller with waterproof plugs,..

Amazon.com

A KT PAS sensor,..
This one you have to pull a crank arm off to install it.

Amazon.com

This one has 12 magnets and can be installed without removing the crank arm.

Amazon.com

And a low profile PAS sensor (I think it's thicker though?)


https://a.co/d/ayOVnwp

And a throttle,..

Amazon.com

 

[PCeBiker]

You've got a standard BAFANG motor connector that would plug into any KT controller that is 500 Watts or less.

EDIT: The KT controllers that are rated 25 amps and up use a different, larger capacity motor cable connector.

Three large pins for the phase wires.
Three small pins for each Hal sensor monitoring each phase wire.
One pin for the Hal sensor monitoring the speed magnets. (Usually 6 speed magnets in a BAFANG hub motor)
As well as positive and negative +5 Volts powering the Hal sensors.


I just took my 500 Watt BAFANG hub motor apart and took a bunch of pictures,..

 

[PCeBiker]

The controller on Amazon is a sine wave type, from what I understand it should be pretty smooth.

My original controller was a sinewave controller but the PAS modes and the throttle kicked in Way Too Hard.

It was like how @harryS described as on/off.

A sinewave controller is quieter than a squarewave controller and is kinder to the motor.
A squarewave controller is more efficient than sinewave, but all that efficiency is lost as heat, noise, and buzzing in the motor.

 

[PCeBiker]

,.. There are no brake switch inputs since it was a torque sensor crank and as long as you stop pedaling, the motor stops instantly.

That's the way the PAS sensor works too, but the sensor can fail and the motor will either not engage, or it won't disengage.

EDIT: The motor should always stop if you stop pedaling, but if the PAS sensor is stuck, your motor could turn on when you pedal backwards.

The throttle can fail too.
If the ground wire disconnects, the open circuit will send the throttle to full power.

I wouldn't want to ride my ebike without brake switches to kill the motor.

The KT controller has two inputs for brake switches and they have add-on switches available that plug directly into the controller.

https://a.aliexpress.com/_mMOug67

 

[PCeBiker]

EDIT:
The controller I linked to has only one brake switch input.
A Y-connector will enable both brake switches.

Amazon.com