Swytch MK2 (Air) motor — want to reuse with KT controller + battery — advice needed!

[snowman77]

Hi everyone,

I’m a Dutch user of the Swytch MK2 (Air) kit. I bought the kit earlier this year, but it had already been sitting in its box for 1 or 2 years before I installed it — “easy does it”!

Unfortunately, after just two months of light use, the display stopped working completely. Possibly the controller or the display malfunction. The battery itself seems fine, but the display does not light up at all anymore.



I also noticed that with moderate assist, the Air battery only gives me about 10km range — a bit disappointing. Now we have moved and I really need around 30km of light assist for commuting.



I can solder and do some basic electrical work, but I’m not an electronics expert. However, I am very good at ordering cheap Chinese parts .



I’ve read a bit about KT controllers (and other open controllers) being an option. I would love to reuse my Swytch MK2 front hub motor and just pair it with a good budget display + battery (with decent BMS).



The problem is: I couldn’t find clear info about what is compatible with the Swytch MK2 motor. I’m happy to change connectors if needed (just need some guidance on the wiring).



Can anyone help me figure out:

1. What kind of controller/display is compatible with the Swytch MK2 motor?
2. What wiring/connector changes would I need to make?
3. Any recommended KT controller/display + battery combo (affordable but reliable)?

Honestly, I have lost a bit of trust in buying a new Swytch MAX battery and display at premium prices — I would much prefer to go the DIY route if it’s doable.



Thanks so much in advance for any tips and experiences!
Snowman

 

[saneagle]

All controllers are comparable with the Swytch motor because they all work the same. There are basically three categories: For sensorless motors; for motors with hall sensors; dual mode that work with both. Assuming that your motor has the standard 9-pin connector and not the 3-pin one, choose a controller for a motor with hall sensors or a dual mode one.

I always recommend KT because they have a better control system than the cheap oner ones, and the difference in performance is easily worth the difference in cost. I also recommend that you get the type with block connectors rather than the ones with sealed waterproof connectors because you can't test the sealed ones if you get any connection sequence problems. You should also get an LCD, throttle and pedal sensor at the same time to ensure compatibility. You can setup the throttle as a boost button, which is very useful and fully legal.

I'm assuming that your Swytch kit has an LCD, which would indicate that there's a speed sensor in the motor. If it's the LED type with no speed display, you should get a speed sensor too.

You can use any battery with a KT controller. Look for a controller that is 36v/48v dual voltage, which gives the option of using more batteries. 48v gives more power for hill-climbing and higher speed (if you want it). If you weigh more than 95kg, 48v is better.

Assuming that it's the normal front wheel kit, you might want to think about fitting at least one torque arm unless your bike has steel forks, especially if you go up to 48v.

If you don't weigh much and/or you don't have to deal with steep hills, a 15 amp max 36v controller should be OK. You can go up to around 17A if you want a bit more help. If you go with 48v, get a 15A one.

 

[snowman77]

Hi saneagle,
thanks for taking the time to explain this so clearly — I really appreciate it!

I will look for a suitable KT controller + display as you suggested.

For the battery, I am considering starting by using two or three Parkside 20V batteries (2x or 3x 4Ah) connected parallel all the way up to 12ah, just to test if the system works — I already have a bunch of those for my DIY projects in house

Of course I understand this is not the safest long-term solution, and I would upgrade to a proper e-bike battery with a good BMS if necessary.

I’ve attached a photo of my motor connector — it’s a 9-pin connector, so I assume it’s the standard one and I will probably need to cut it off.

I hope I can figure out the pin layout so I can wire it correctly to the new controller.

Is there any particular KT controller you would recommend that works well with a voltage range starting from ~18V (or ideally supports also 36V and 48V when I upgrade my batteries?

I think I need to go with one of these or won't that work?

KT24/36/48SVPR Sine-Wave

Windmeile KT 24–48V

Elifebike KT Sine-Wave 24–48V

Or is this approach (with Parkside batteries) too risky or unreliable for testing?

Thanks again for your help!

 

[thelarkbox]

Yes a standard motor 9 pin connector, Be mindful the pins are delicate, 1x already looks a bit bent, tho cld just be a pic artefact? perhaps a big blob of blutack to protect em till the new kit arrives..

re testing with 20v batteries, no- just dont, for one while ads will headline 24/36/48v options when you dive a lil deeper the options will be 24/36v and 36/48v etc you may find exceptions,, but so far i cant recall ever seeing any.. (edit, fwiw imho 36/48v dual voltage option is superior to 24/36v option for most cases, -power/range capacity etc.. )

You can use power tool batteries and many have built and designed 3d printable socket solutions, there are a few buts and if a real e bike battery is a viable option budget wise its the best option unless you are prepared for a 100 hours of intensive browser starring research . (well thats what i would need,,)
then you get into mechanical mounting issues and weatherproofing/splash proofing..

A bench psu or even a ebike battery charger can provide the required volts to turn on and configure an ebike control system and even drive the motor upto 4-6km/h walk mode when so configured.. However attempting to run the motor full speed WILL DRAW TOO MUCH POWER (amps)

Sinewave controllers are a little more complex and expensive than square wave controllers they are supposed to run the motor more smoothly and quietly, i screwed up and bought a bargain $5 cheaper square wave controller (the add just didnt specify which) , it works.. and the difference is subtle but noticeable.
google suggests if "SVP" is included in the model number its probably a sine wave controller and if "ZWS" is in the model number its probably a square wave controller..

 

[saneagle]

I'm not sure about Parkside batteries, but most like that don't have the necessary safety controls. They rely on the unit they power to look after that, so it's always a bit dodgy going in that direction. Good ebike batteries can be had from PSWPower very cheaply if on a tight budget, otherwise you might as well get a battery fit for the purpose at the beginning if you serious about having an electric bike. Those Parkside batteries would be OK for testing or something like that, but I wouldn't advise using them for any permanent solution.