TSDZ2– No overheating for me

[Bikes4two]

TSDZ2– No overheating for me

Here’s my observation about motor overheating (or not). I hope those who may have been put off looking into using the TSDZ2 because of this issue, find the following useful, and of course your own observations and comments are welcome (but no repeating unsubstantiated web chatter please).

• You won’t have to look far on the internet, especially the Endless Sphere forum, to find tales of the TSDZ2 overheating, causing the motor magnets to demagnetise and rendering the motor useless. And there’s a whole group of folks who have come up with different methods of keeping the motor cooler.
  
• What you won’t find much about is exactly how the motor was being used. By this I mean was it being driven at full assist with a 52v battery at maximum current on a red hot day somewhere in the wilds, or ridden by someone like me using the lowest power setting on a 36v 250w version of the motor in UK temperatures.
  
• Whilst I have no doubts that under certain circumstances the motor can overheat, what I can tell you is that I’ve ridden my TSDZ2 for nearly 3,000Km now and the last 300km was in France last week (June 2022) during their heat wave in temperatures toping out at 35degC at times and I have not had an overheating issues or even anything approaching it.

My Riding Profile

• Firstly, how do I use my TSDZ2? I’m retired, fairly fit for my age and ride on road around 150Km a week this time of year (if it’s not raining or too cold – yeh, a fair weather cyclist!).
  
• The TSDZ2 is on a converted Dawes Galaxy which with all the paraphernalia on it comes in at around 20Kg plus me at around 97Kg.
  
• I also run the motor with the Open Source Firmware (v20.1c) using only the Power Assist Mode with ECO set to 50% assist.
  
• I first used the bike to recover from a long downtime and I now ride it almost exclusively on the lowest power setting (ECO) and in my home area of South Hampshire, where the terrain is a mix of flat and the South Downs hills. (I get 50+ miles out of my 10Ah battery).

Temperature Monitoring

• To monitor motor temperature I used RS Components ‘RS PRO Non-Reversible Temperature Sensitive Labels’ which come in various temperature ranges and cost less than £20 for 10.
  
• These are on shot temperature sensitive strips and I fitted one label to the outer motor casing for any early warning of over heating, and one to the motor itself (It takes around 10 minutes to remove the left crank, motor assembly lock nut and motor casing and re-assemble).
  
• As you can see from the pictures, neither label has registered any temperature above the label’s lower reading of 77degC. (The red gunk in the pictures is ‘red rubber grease’ which I use on the motor casing seal).
  
• Further, I did on a regular basis during riding, put my hand on the motor casing to see how warm it was and it never got anything above luke warm.

Conclusion
For my style of riding I have no concerns about overheating. However, if say you use the motor more aggressively than I do, e.g. consistently higher assist levels, high voltages and higher rated/powered motors, then maybe you should read more about the issues around overheating and cooling on Endless Sphere. You could of course buy some RS Pro labels as a first measure and maybe save yourself some time and trouble fitting goodness knows what to your motor when you don’t need to.

Footnote on De-magnetisation of Neodymium Magnets

• I read a number of articles on this subject and found this one here quite useful.
  
• In essence it seems that whilst the magnets seem to like cool operating conditions, its also the case that the composition of the magnets can be manufactured to perform at different temperatures.
  
• Further, to quote from the article “… some grades of neodymium magnets can also be exposed to very high temperatures before their properties begin to change and they lose their magnetism, either temporarily or permanently.”
  
• So far I’ve not found anything about the design characteristics of the magnets used in the TSDZ2, so from that point of view I’ve no idea what a ‘safe’ operating temperature range might be.

 

[Sturmey]

One thing I notice and think is well worth considering is the cadence of the rider. If the cadence (and therefore the motor) can be kept spinning fast enough (>70 rpm), the motor seems to stay cool.
PS. re the magnets, the motor is an 'inrunner' in that the rotating magnets are enclosed inside the copper windings (rather than on the outside with hub motors), and I presume they have a harder life if the motor windings get hot.