TSDZ2 - 48V or 52V for Cargo Bike

TCW

1 µW
Joined
Jun 11, 2022
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I'm planning to add the TSDZ2 to my Bakfiets.nl classic long cargo bike. I value the natural feel of cycling and so this coupled with a blog of someone successfully adding the TSDZ2 to my exact bike has lead me to settling on the torque sensing TSDZ2.

I'm planning to buy the 48V version via ECO Cycles since they seem to sell the TSDZ2 in a 'build your own' format that comes preinstalled with the open source firmware version and temperature sensor which appeals to me. The main question I have is whether to go for a 48V or 52V battery. High speeds are not at all what I'm after, just moderate assistance to 25km/h and help on the occasional hill I'll encounter on each ride.

  • My initial thoughts were to simply get a 48V battery since that was the version of the TSDZ2 I'm getting and I'm not interested in overvolting a motor to the brink. I value reliability and simplicity for this build.
  • On the other hand (after some reading) a 52V battery may be useful for my cargo bike build since for a given power output the motor would require less current (P=VI) and therefore less heat through the motor windings. I'm aware of the TSDZ2's limited ability to dissipate heat and so this may be beneficial for a cargo bike. Is my understanding correct?

What are some other pros and cons of a 52V battery when compared to a 48V?
Is a 52V battery still ultimately going to push the motor too hard? (I'm aware of setting the max current in the firmware)
Will I get reliability issues - i.e. does a 52V work seamlessly with the open source firmware?
Any efficiency gains of one voltage over the other?

Voltage decisions aside, has anyone got experience with the batteries sold by ECO Cycles compared to em3ev batteries?
Buying it all from ECO cycles and paying one amount for shipping is more cost effective, however the em3ev batteries are held in such high regard that at this stage I'm willing to buy the battery separately from them.

Thanks in advance for your help
 
You have correctly summed up the advantages of running the motor with a 52V battery.
I use one on mine (48V motor, power/current limit 750W/15A) and it works just fine with OSF. The difference with a 48V battery is probably not huge though.
Besides heat considerations, another advantage of a higher voltage battery is the higher pedalling cadence with assist. The field weakening option in OSF does compensate for this with lower voltage batteries, but at the cost of a reduced efficiency.

However, for use with a cargo bike (or, in general, if you want to use more than 500W of power) I strongly recommend doing a heat dissipation mod.
As you mentioned, without it the motor can overheat, and reach well over 70°C very, very quickly (the exact temperature from which there is permanent damage to the motor magnets is not exactly known).
I did an extensive heat dissipation mod on mine and I can pull 750W for a comfortable amount of time before overheating (actually I haven't reached the temperature limit since I did the mod, while I would reach it in a few minutes without the mod when pulling 750W).
There is a dedicated thread for this : https://endless-sphere.com/forums/viewtopic.php?f=28&t=102046

Adding 6902 bearings on both sides of the axle also helps protecting it when pushing hard on the cranks.

It's a nice, cheap little motor but unfortunalely requires some work beforehand if you want to get the best out of it.
 
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