SOURLEMONJUICE

Now the question is, will the KT system somehow read the speed from 3 hall sensors? Or do I need the external speed sensor?

Thanks for recommendation, I'll move to KT.

Hi, I did some research and yes KT will be the solution. Thanks

They are both 6 speed, identical freewheel and handlebar shifter. Forgot to mention d4s has 20inch wheels and d2s 16inch wheels. Now I know d4s has one extra wire for speed sensor(?), so there will be probably issue with speed reading when use d4s components?

Bellow is answer from Fiido support when I asked for both motors specs. D4S motor: motor~20 "CZJB90TZ rear 36V 250W rear left inner outlet, disc brake OLD 137 6S thread 36H 13G black with one speed gauge, wire length 800mm, maximum speed 31km/h 9-core ordinary wire, phase wire 3C head, Hall 2 8-piece flange nut with rubber sleeve D2S motor: 36V 16 inch high-speed integrated wheel motor, equipped with 6-speed flywheel, all sub black color, disc brake variable speed, imperial thread, 145mm on gear, load speed of 25 kilometers per hour, right outlet, with internal speed measurement, ordinary nine core wire length of 710mm (excluding wire stripping)

Hi, thanks for comment. I forgot to mention in firs post that the battery is fully charged and holding 41.8V over last few days. So battery is not the issue

Thanks for explaining the wiring, anyway there is no extra 3 wires. By the 3 wires beside the terminal connector was meaning 3 thick phase power wires. I just double checked the controller/motor wiring and there is 5 wires (black, blue, yellow, red and green) on terminal and 3 phase wires, so total 8 for d2s. Also I checked photos of d4s controller and there is one white wire extra compare to d2s controller. So 9 in total (black, blue, yellow, red, green and white[speed sensor?]). That mean the motors are not identical and with d4s controller and display connected to d2s motor it would run but no speed reading...CORRECT?

Hi, thanks for reply. Both motors have 3 wires beside the 9 pin connector. Can I ask why this should be a problem?

I already checked all possible websites that are selling fiido parts, but there is lack of specs.. As you saying, the wires on the d4s photo from their website are not fitted in the terminal, anyway the wiring and colour coding are identical. Just swapping the pins in the terminal will do the job. Possible crimping or soldering is no problem, but in this case not required. I worried more about the speed sensor output. I contacted Fiido support again to send me detailed specs of both motors..

Both models are fitted with 36V , 250w brushless motor. Design are different, battery on d4s has slightly larger capacity, but that's all. In my opinion, a controller and display unit from d4s should work with a d2s motor without any problems. Please correct me if I'm wrong. Thank you

Hi, thanks for answer. I understand and totally agree with you. Anyway as I mentioned I would like to order both, handlebar display unit and controller for d4s. I wonder if anyone sees a potential problem in this. So, if someone could confirm for me whether the engines from both models are identical, in my opinion that is the only thing that could cause a compatibility problem

I did, their support worker doesn't seems to be much helpful in technical questions. They said that the g20 display unit were never mounted on d2s, which is not true. Also they mentioned that the motor is different on d4s, by tech. specifications I found, they are identical..

Hi guys Qiuck question, I got second hand d2s which doesn't turning ON. As I will need to replace handlebar display and controller, I was thinking to order both parts for d4s to get little bit more features. To me motor on both ebikes looks identical, and other parts shouldn't cause any problems. Did someone tried to use those or upgrade d2s with aftermarket display and controller? Thanks