TSDZ2B (2025) Failure - Heavy Resistance from Day 1 & Seized Motor Core

[Mahis]

Hi everyone,

I’m seeking technical insight into a progressive failure of my TSDZ2B (48V system, 860C display, 960Wh battery, Batch tf2025h).

Phase 1: Initial symptoms (The first 50 km)

From the very first ride, the bike felt unusually heavy to pedal without assistance. I configured the display for 3 assist levels and used only Level 1. Despite the light assist and the large 960Wh battery, I only got about 50 km before the battery died very unexpectedly (likely a sudden voltage sag under load).

Phase 2: Total failure

The unit has now failed completely:

Manual test: With the drivetrain removed and phase wires separated, the bare motor core is extremely stiff to turn by hand and makes a grinding noise.

Power test: Under throttle, the motor barely rotates, struggles, and gets very hot almost instantly.

Two Theories – What happened?

Mechanical Drag in Housing: Could a manufacturing defect or misalignment in the main housing/shaft bearings have created enough constant friction to make unassisted pedaling heavy and eventually overload the motor to the point of seizure?

Defective Motor Core (The "Lemon"): Alternatively, could this be caused purely by a faulty motor core from the factory? If the motor had internal mechanical interference or a shorted winding from day one, would that explain the heavy pedaling feel and the extreme energy consumption even on Level 1?

Questions for the community:

Has anyone experienced this level of resistance "out of the box" with the 2025 "tf" batches?

Given the symptoms, does this sound like a housing/bearing issue that killed the motor, or just a DOA motor core?

With a 960Wh battery, 50 km on Level 1 is approx. 19.2 Wh/km. How much of that was likely lost to internal heat/friction?

I’ve attached a video of the seized motor core. Any insights would be much appreciated!


Link to video

 

[dgc]

I can get 30 miles on a 36V 10Ah (360Wh) battery riding on the flat with some inclines. You feel the magnetic "poles" as you turn the motor shaft other than that it turns easy with no noise. I have had many TSDZ2(B)s. Duff motor, yes, DOA yes, you may have answered your own question with "With the drive-train removed and phase wires separated, the bare motor core is extremely stiff to turn by hand and makes a grinding noise". Is this unit new out of the box? from where? was the delivery packaging damaged when you received it? or had it been dropped? Cannot remember the internals of these motor, thinking it could have dropped a magnet segment or two, is there shaft movement on the bearings? For a start.

 

[dgc]

Watch the video again, the TSDZ2(B)s tend to have what I call sloppy fits on their bearing, I checked a couple of bare motors I have and yes if you turn their shaft the casing will tend try and follow but there is no grinding noise, the stator could broken up, have to open the motor up to find out, or it's 55 euro for a bare motor.

 

[Mahis]

Thanks for reply. I think motor is definitly Broken. I wanted to know if something caused it to overheat and fail. Do you think it is normal that main shaft has that much friction and noise?

 

[Zambam]

Thanks for reply. I think motor is definitly Broken. I wanted to know if something caused it to overheat and fail. Do you think it is normal that main shaft has that much friction and noise?

Of course it's not normal!

Did you test ride the bike with power off to the motor before the noise and friction started? Did it ride normal or was there a lot of resistance?

 

[Mahis]

Hi. I did pedals without assistance before motor broke up.
It felt that there was sometimes More resistance. Sometimes More, sometimes less. Also range was surpricingly low. Resistance was not very heavy. Definitly More than on bike without assistance. I mean bike without motor at all. If this is normal I'll just Renew motor and hope it lasts longer than 300km.

 

[themountain]

Just send it back

 

[dgc]

Just send it back

As said here you have not said if it is brand new or not.

 

[OlderGiantFan]

Bafang mid-drive motors are tested before, during, and after assembly to ensure quality. This includes testing the controller function and a full loading test under simulated road conditions. The TSDZ2B mid-drive motor is a budget-friendly torque-sensing motor praised for a natural riding feel, but it is generally considered less reliable than premium options like Bosch or competitors like Bafang

to cut out the intro stuff 7:40s

 

[Mahis]

As said here you have not said if it is brand new or not.

Tongsheng TSDZ2b and battery are installed about one month and they were brand new. Assistance worked on The beginning. But range was poor from The beginning. I am new with these assisted bike systems so I am not sure how much IT should assist and how heavy IT should Be to driver without assistance etc. But I was suspicioius right on The beginning because of poor range and heavy pedaling without assistance. TSDZ2B Have this two way clutch and it is claimed to Be driveable without assistance.
I Also noticed that motor gets quite hot during ride Even when there is zero Celsius degrees outside.
BR Marko

 

[Zambam]

Tongsheng TSDZ2b and battery are installed about one month and they were brand new.

Hope you bought it from a supplier who will honor your warranty claim.

 

[Mahis]

Hope you bought it from a supplier who will honor your warranty claim.

Yes. I bought it from PSWPower and we have had good discussions. It's not quite clear what is broken. Let's see if get common understanding.

 

[dgc]

My feeling about PSWPower, I have had no problems with them, I have brought a number of TSDZ2(B)s along with importantly a few faulty returns which I originally brought for spare parts and subsequently repaired, (retired engineer needing something do). Anyway something to look at knew I had seen it somewhere and it's here, bare motor in bits, TSDZ2 Bare Motor Strip-down I even commented on it, brain gone.

 

[Zambam]

Anyway something to look at knew I had seen it somewhere and it's here, bare motor in bits, TSDZ2 Bare Motor Strip-down I even commented on it, brain gone.

@bikes4two's thread is from June 2023. Title says TSDZ2. Is that correct or does he have TSDZ2B's?

I asked google "when did TSDZ2 motor stop being sold"

Answer:
AI Overview

The original Tongsheng TSDZ2 motor was effectively pulled from major Western markets, such as AliExpress and Amazon, around September 2021 following a lawsuit by Bafang for patent infringement.
While the original TSDZ2 was phased out, it was not completely discontinued. Instead, it was replaced by the updated TSDZ2B model to navigate the patent issues, with dealers like PSWPower maintaining stock.
Key Trends & Replacement Info:

• The TSDZ2B Transition: The TSDZ2B, which addressed structural weaknesses like the cracking casing, became the standard replacement for the original version.
  Endless Sphere DIY EV Forum +1
• Availability: While you can still find new TSDZ2B kits as of 2024, the market has shifted towards the newer TSDZ8, and some users are experiencing limited, or inconsistent availability.
• Support: Parts for the original TSDZ2 remain easy to find, and many sellers still offer the updated TSDZ2B kits.
• Market Shifts: Many sellers now recommend moving toward the TSDZ8, though some continue to use the updated TSDZ2B.

 

[dgc]

Years back I had a AKM mid-drive unlike the TSDZ2 that was a clone of the Bafang mid-drive, even worked the same way. Myself I still like the TSDZ2 and TSDZ2B mid-drives as I have with a bit of luck enough spare parts. I have said before I do a mild tune so as to not turn them inside out power wise, I fit the extra support bearings etc, they suit me fine, have covered thousands of miles. Have a 3D stl main gear cover file for allowing a TSDZ2B main gear to fit a TSDZ2 mid-drive to print at some time. Do fancy trying a TSDZ8 but not in a rush.

 

[Mahis]

It seems that supplier will send me new motor. That's very good.
I would like to make sure new motor lasts longer. What kind of cooling solutions you recommend? I have heard that there are cooling kits available. How about OSF? Is it worth installing and what hw I need to be able to install ?

 

[dgc]

I run the OSF on my bikes, but I only do a slight "tune up" to suit myself for better rideability, which means I do not bugger the drives up over powering them, but I have done the bearing mods on the thro axle, there a videos for that as well. Have a look at this video this is where I started.

Luke has a series of videos. You will need the the ST-Link V2 adapter to plug into a computer or laptop and go from there. There are many videos around regarding the programing software. I use the DZ41 Display UART Tongsheng TSDZ2 compatible 6 pin mostly and modded the display cable so I can use brake sensors as the DZ41 doe's not have a brake option.

IMPORTANT. Where did you buy your drive from as there a two versions, there is the V1 controller which is programmable and the V2 controller which not programmable. I even brought a TSDZ2B as a non working return from PSWPower and switched the controller from a V2 to a V1 which is on my 29er. Have a look at the link below, and there is a way to check which controller you have on this site will try find link saving you having to take the drive apart.

TSDZ2 OSF for all displays, VLCD5-VLCD6-XH18, LCD3, 860C-850C-SW102.

One question: have you also tried v20.1C.5? To understand the source of the problem, it's important for me to know if this version also has the same issue. If you haven't tried it, can you? Thanks. I haven't tested version 20.1C.5. I can test it after my vacation (early September). Regards

endless-sphere.com

 

[dgc]

In fact read the whole thread.

 

[Zambam]

What kind of cooling solutions you recommend? I have heard that there are cooling kits available.

What kind of terrain and riding? What's bike's and your weight? How fast do you want to go?

On my TSDZ2, I bought all the parts needed for cooling mod. I then bought a $4 thermocouple meter, epoxied the probe on the motor stator lamination (quick and easy), learned that I could not get the motor hotter than 60 C in the heat of summer with the kind of riding I do. So I did not need to install the cooling mod stuff, which is messy and makes servicing the motor more difficult.

 

[Mahis]

What kind of terrain and riding? What's bike's and your weight? How fast do you want to go?

On my TSDZ2, I bought all the parts needed for cooling mod. I then bought a $4 thermocouple meter, epoxied the probe on the motor stator lamination (quick and easy), learned that I could not get the motor hotter than 60 C in the heat of summer with the kind of riding I do. So I did not need to install the cooling mod stuff, which is messy and makes servicing the motor more difficult.

I drive bike mostly on asphalt roads. 20 km to work and back. I am about 95 kg and Max speed is 30-35 km/h. I guess my 26 inch wheeled hardtail is about 25 kg with motor and battery.

Some budget friendly solution would be good. Equipment needed for programming seems to quite pricy. I have to find out if I have controller version V1 or V2.

 

[dgc]

It's down to if you can use a solder iron or not, the st-link v2 are about 6 euros and a cable to cut back about 7 euro, all the software is free.

Before anything else regarding the controller type look here. TSDZ2 - When were the non OSF flashable controllers introduced?

Not sure currently if you program the V2 with a J-link cable, I have had no need as I have a few V1 36V and 48V controller as spares.

 

[Zambam]

I drive bike mostly on asphalt roads. 20 km to work and back. I am about 95 kg and Max speed is 30-35 km/h. I guess my 26 inch wheeled hardtail is about 25 kg with motor and battery.

Some budget friendly solution would be good. Equipment needed for programming seems to quite pricy. I have to find out if I have controller version V1 or V2.

I'd suggest install new motor, see how it performs stock, whether it meet your expectations or not, before deciding if you want to go OSF.

 

[dgc]

Good idea, see how it feels, there was two reasons I use the OSF, first I like / use the Hybrid Assist Mode to improve rideability etc on my 36V e-bike and on my 48V e-bike as well as using the Hybrid Assist Mode I increased by 20% the Power and Torque Assist Mode values to give me the same feel as on my other bike, did not want a this point in time to open the drive up and mess with the torque sensor.

 

[Mahis]

It's down to if you can use a solder iron or not, the st-link v2 are about 6 euros and a cable to cut back about 7 euro, all the software is free.

Before anything else regarding the controller type look here. TSDZ2 - When were the non OSF flashable controllers introduced?

Not sure currently if you program the V2 with a J-link cable, I have had no need as I have a few V1 36V and 48V controller as spares.

I think I can solder. Just have to find right parts. I have understood that it could be worth of upgrading SW to 860C display unit and it needs own programming cable. It seems to something like 60 euros in ebikestuff.

 

[Mahis]

I'd suggest install new motor, see how it performs stock, whether it meet your expectations or not, before deciding if you want to go OSF.

This sounds like a good idea. Some cooling improvement. Maybe.