2014 S-Pedelec Lishui controller replacement

Hi guys,

After a few years absence from e-bike building I'm back on ES once again, trying to remember all sorts of technical Ebike stuff I knew a couple of years ago

I have a 2014 S-pedelec (cheap and obscure brand that doesn't exist anymore) that I bought used in 2018. Since then, I've used it as a daily commuter. Apart from a new battery, it has run without any issues.

Current setup:
Bafang (8-Fun) 500W rear hub motor (with at least 15.000km in all weather conditions on it, possibly a lot more. Still runs great!)
Lishui LSW772-96F 48V 20A controller. Date of mfg. 2014.
Bafang 850C display (uses non-Bafang firmware made by the bike company that has some limitations, like speed limit of 45km/h that can't be changed as that is a legal requirement for S-pedelecs here)
48V20Ah battery pack

Lately I've had some issues that I think are due to a bad controller, but I would like your opinion:

Last week when I took it off the charger I noticed that according to the display the battery was at 56V.
After panicking that the charger/BMS somehow overcharged/destroyed the pack I took out my multimeter and measured the battery to be at a perfectly fine 52V. Since then, the voltage indicator on the display has consistently read too high, but everything works fine.

Yesterday the PAS started cutting out. While pedaling, the power would cut randomly, to come back after a random time and cut out again. There are no errors displayed. The display has no 'PAS active' indicator, so I can't see if it is registering pedaling.
When using the throttle everything worked fine, but throttle is limited to 25 km/h
Suspecting a dirty/faulty PAS, when I came home I cleaned the PAS and checked the wiring.
The PAS LED blinks every time a magnet passes, magnets and gap are OK, so the PAS seems fine, but there is no response from the motor.

Link to image of the controller:
https://ibb.co/F5LT9R3

The controller is hidden inside the frame (and is a major PITA to remove/install). It has suffered no water/moisture damage and all connectors inside the frame look like they were made yesterday. But it still is an 8 year old controller with a lot of km's on it. Combining that with the issues above makes me think it is time to replace the controller. But with what?

I've read this topic that updated just a few days ago https://endless-sphere.com/forums/viewtopic.php?f=2&t=116101 with great interest. If possible, I would like to replace the controller with a KT 22A controller as well. It looks like they are made in different configurations, with a 'Bafang' style as well, that seems to match the waterproof connectors on my bike. (It has the 4-to-1 connector that my bike has as well)
Would I be able to still use my current Bafang 850C with such a KT controller? Or do I need to get the KT-LCD4 as well?

Last question: as I need this bike for my daily commute, are there any local webshops that ship to Belgium within a few days?
Searching turns up a few UK shops, but they don't ship to the mainland.
I used to order my ebike stuff from BMS battery or Aliexpress but this time I cant afford to wait for a month for new parts

PeterT12 said:

Last week when I took it off the charger I noticed that according to the display the battery was at 56V.
After panicking that the charger/BMS somehow overcharged/destroyed the pack I took out my multimeter and measured the battery to be at a perfectly fine 52V. Since then, the voltage indicator on the display has consistently read too high, but everything works fine.

Yesterday the PAS started cutting out. While pedaling, the power would cut randomly, to come back after a random time and cut out again. There are no errors displayed. The display has no 'PAS active' indicator, so I can't see if it is registering pedaling.
When using the throttle everything worked fine, but throttle is limited to 25 km/h
Suspecting a dirty/faulty PAS, when I came home I cleaned the PAS and checked the wiring.
The PAS LED blinks every time a magnet passes, magnets and gap are OK, so the PAS seems fine, but there is no response from the motor.

Click to expand...

I realize you're probably not really trying to troubleshoot the system, but since I don't have information helpful to your upgrade questions:

If the controller has an HVC (where it stops operating above a certain voltage to protect itself, just like the LVC to protect the battery), perhaps whatever is wrong with it that causes it to see too high a voltage is now seeing a high enough voltage that it is beyond it's HVC.

If there is electrical noise in the system (which always happens when the motor is running, but could happen at any time), and capacitors (especially teh can-style ones) have failed, the noise could affect operation of the system.

If it has ebrake levers, there could be a wiring or switch fault causing false operation of the ebrake line, causing the controller to stay inactive while otherwise operating normally. (the fault could happen anywhere up to the PCB inside teh controller, but is much more likely at the lever itself or the connector to the controller).

Thanks for the reply.
I did some more troubleshooting and in the process managed to destroy the display
(while measuring the battery voltage at the display terminals managed to short Batt+ en Batt-. Small explosion, but the BMS/pack is fine)
So now I'm definitely looking for a new controller/display combo.

I found out that the motor is actually a sensorless motor. Never really counted the pins in the connector (just knew it was more then 3, so concluded it must be with hall sensors).
It actually is a 6 pin connector, which after searching seems to be an old Bafang sensorless motor with the extra wires used for a speed sensor.
I happened to have a spare S-KU63 controller that supports both sensored and sensorless and works fine on this bike, but is only 36V/15A.

I found a KT controller online that perfectly matches the connectors on this bike (except for the motor connector).
But I can't seem to figure out if this controller also supports sensorless motors. I've found that the KT controllers come in 3 flavors: Sensored, sensorless and dual mode.
But how can I see from the product code which is which? The seller doesn't know, and he is the only one offering this exact controller (amps, connectors, light wire).

There may be info on whcih ones support which functions in one of the KT Kunteng Open Source Firmware OSFW threads.
https://endless-sphere.com/forums/viewtopic.php?f=30&t=87870

More here, but most not relevant:
https://endless-sphere.com/forums/search.php?keywords=kunteng+open+source+firmware&terms=all&author=&sc=1&sf=all&sr=topics&sk=t&sd=d&st=0&ch=300&t=0&submit=Search

Just letting you guys know that this problem has finally been solved and a suitable replacement controller found!

Since I already had a KT-LCD4, I needed a KT controller. It was quite difficult to find a suitable controller that support sensorless motors (marketed as Dual Mode) AND also has the correct Julet connectors I was after.
The controllers seem to be made in many different versions and most sellers on Aliexpress have no clue what they are actually selling :lol:

So if you're looking for a 22A KT controller for a sensorless motor that has waterproof Julet connectors AND a separate light wire:
In the end I got this controller from ChamRider (the one explicitly mentioned as 22A Dual Mode):
https://nl.aliexpress.com/item/4001038008873.html

The bike runs great again! Thanks for the help.