Converting from Swytch to standard equipment

rig the jig

Pedelecer
Dec 29, 2019
41
2
Hi I'm new to this forum, I'm a semi retired office equipment technician, I want to convert my Swytch bike to standard 36V 15A.H. battery. The 250W wheel on the Swytch is a 9 pin sensorless wheel, so I 'm looking for a sensorless controller, that will support PAS, a display, and a throttle. From reading various posts I think I need a KT 22Amp controller. Can anybody advise me on this please.
Kind regards
Rig the Jig.
 

saneagle

Esteemed Pedelecer
Oct 10, 2010
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I think 22A is too much for the Swytch motor. There's a fair chance that you'll strip the gears. If you want it to last, 18A is about as high as I'd go at 36v.

A nine pin connector would normally indicate a sensored motor. Did you check and find so e not connected?
 

rig the jig

Pedelecer
Dec 29, 2019
41
2
Thanks for the quick reply, its definitely a nine pin connector, and I'll take your advice on the 18A or less. Does the amperage of the battery have an effect on the motor, is 15 Amp 36V ok?
 
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saneagle

Esteemed Pedelecer
Oct 10, 2010
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Thanks for the quick reply, its definitely a nine pin connector, and I'll take your advice on the 18A or less. Does the amperage of the battery have an effect on the motor, is 15 Amp 36V ok?
The battery needs to be able to provide the current that the controller allows plus some headroom. I'd allow 5A headroom, so a minimum 20A battery for 15A controller and 25A battery for a 20A controller. You'd probably be OK with a 20A battery for a 17A controller.

Don't get mixed up between amps (current) and amp-hours (capacity).
 
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rig the jig

Pedelecer
Dec 29, 2019
41
2
The battery needs to be able to provide the current that the controller allows plus some headroom. I'd allow 5A headroom, so a minimum 20A battery for 15A controller and 25A battery for a 20A controller. You'd probably be OK with a 20A battery for a 17A controller.

Don't get mixed up between amps (current) and amp-hours (capacity).
Thanks so much for the good advice.
Rig the jig
 

Cisco-man

Pedelecer
Sep 27, 2023
154
29
I think 22A is too much for the Swytch motor. There's a fair chance that you'll strip the gears. If you want it to last, 18A is about as high as I'd go at 36v.

A nine pin connector would normally indicate a sensored motor. Did you check and find so e not connected?
Hi Saneagle. I’m glad I saw this post. I’ve been considering moving to a KT22 controller when I move away from my Swytch setup - but retaining the Swytch hub. I didn’t realise that the controller was the limiting factor regarding max current drawn. I assumed (wrongly it appears) that I had a 250w hub and that would limit the max current. What KT controller would keep my setup legal in the UK?
 

Nealh

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Aug 7, 2014
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There is no set limit on current on can use, all that matters is the motor is 250w rated. That said one has to be careful with how much current one applies as eventually the motor may get hot and strip the nylon planetary gears.
One should be fine with 22a for short bursts, typically 15 - 18a is fine and 20a maybe ok , it really depends on the motor and voltage.
 

Cisco-man

Pedelecer
Sep 27, 2023
154
29
There is no set limit on current on can use, all that matters is the motor is 250w rated. That said one has to be careful with how much current one applies as eventually the motor may get hot and strip the nylon planetary gears.
One should be fine with 22a for short bursts, typically 15 - 18a is fine and 20a maybe ok , it really depends on the motor and voltage.
Thanks Nealh - but surely in the UK anything over approx 8 amps on a 36v wheel would be pushing more than 250w. I’m trying to establish what keeps it all uk-legal. Is it a setting in the controller that limits the power to legal limits? Am I allowed to burst to higher powers on a 250w hub?
 

Cisco-man

Pedelecer
Sep 27, 2023
154
29
Ah, I see the point. So I can push as much power as I like - as long as the hub is RATED as 250w. sorry for being thick!
 

Nealh

Esteemed Pedelecer
Aug 7, 2014
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Yes correct , one can push 1000w if you like thru a 250w rated motor as that is the relevent law and legal.
In reverse putting 250w thru a 1000w rated motor is illegal because of the motor rating.
With the 250w rated motor the power is a temporay power.

The risk which one has to weigh up is if the 250w motor can take xxx power before either the windings burn/heat up and demagnitise or the nylon gears go gooey.
One is better to apply 48v at say 15a rather the 36a at 22a.

If the current is judicially used one will be surprised how much power can be used with a 250w motor if one doesn't live in too a hilly location.

On the German pedelec forum one use fitted a Bafang sxwh hub to a tadpole trike, with some motor cooling he put 2kw thru the hub.
 
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rig the jig

Pedelecer
Dec 29, 2019
41
2
Yes correct , one can push 1000w if you like thru a 250w rated motor as that is the relevent law and legal.
In reverse putting 250w thru a 1000w rated motor is illegal because of the motor rating.
With the 250w rated motor the power is a temporay power.

The risk which one has to weigh up is if the 250w motor can take xxx power before either the windings burn/heat up and demagnitise or the nylon gears go gooey.
One is better to apply 48v at say 15a rather the 36a at 22a.

If the current is judicially used one will be surprised how much power can be used with a 250w motor if one doesn't live in too a hilly location.

On the German pedelec forum one use fitted a Bafang sxwh hub to a tadpole trike, with some motor cooling he put 2kw thru the hub.
Hi , could anyone recommend a K2 36V 15A controller that would fit the swytch 250W motor with a 9 pin connector, that is coupled with an LCD back lit display, a throttle connection , and a PAS .
 

Cisco-man

Pedelecer
Sep 27, 2023
154
29
Hi , could anyone recommend a K2 36V 15A controller that would fit the swytch 250W motor with a 9 pin connector, that is coupled with an LCD back lit display, a throttle connection , and a PAS .
For me too please! I’ve landed on the KT37/48SVPR-EP02B as being a likely choice, because it opens the door for 48v later on too, but I’m confused by the connectors. The information I have found puzzles rather than helps. I’m guessing that you buy a controller + display and a connection conversion harness comes with it? Where does one go to buy what we need at the right price? All help appreciated!
 

Woosh

Trade Member
May 19, 2012
19,294
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Southend on Sea
wooshbikes.co.uk
I don't understand the advice given to the OP. He's got a fully working kit, he wants a bigger battery. Why change the controller?
 

saneagle

Esteemed Pedelecer
Oct 10, 2010
3,540
1,763
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For me too please! I’ve landed on the KT37/48SVPR-EP02B as being a likely choice, because it opens the door for 48v later on too, but I’m confused by the connectors. The information I have found puzzles rather than helps. I’m guessing that you buy a controller + display and a connection conversion harness comes with it? Where does one go to buy what we need at the right price? All help appreciated!
You buy the controller, connect the battery, motor and LCD, then the throttle test it, connect the PAS (not 12 magnet one), brakes and speed sensor (optional), do the settings and ride the bike. It's as simple as that.

Potential problems:
  • You forgot to read the manual
  • You don't know how to connect wires in the right sequence
  • You went against our advice and fitted a 12 magnet sensor
  • You can't understand push the motor connector in all the way to the line
  • You thought the connectors for your previous controller were the same as KT ones because they fit
  • You forgot to buy a throttle for testing
  • You connected a fully-charged 36v battery or a completely discharged 48v one so that the controller couldn't figure out what you had.
  • Your motor has an unusual hall phase sequence and you didn't think to try different connection sequences to get the right one. because your ADHD can't deal with connecting a blue wire to a green one
 

Cisco-man

Pedelecer
Sep 27, 2023
154
29
Beacause the original controller is shite!
I was waiting for the OP to reply, but Saneagle is definitely right! I can’t adjust anything on it, it’s locked down pretty tight.
I’m not faint-hearted, I’ve investigated the current swytch setup so I understand every wire and signal. I just don’t want to spend c. £100 and buy the wrong thing. Interesting you should say about the 12 magnet sensor - I hadn’t heard of that before. I’ll see what the swytch sensor is…
 

saneagle

Esteemed Pedelecer
Oct 10, 2010
3,540
1,763
Telford
… it’s 12. So the Swytch PAS is no good.
It might work and it might not. All we know is that every time someone can't get the PAS to work, it's a 12 magnet one. They then buy an 8 or 10 magnet one and it works. I've had 12 magnet ones work OK, and on one bike (Freego)with OEM controller, the guy broke his pedal sensor., which was a large 8 (?) magnet one. The only one I could find in that size had 12 magnets. I couldn't make it work, then I took out every other magnet to convert it to 6 magnets, and it worked perfectly.
 

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