BBS02 Improving Heat Dissipation

hias9

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I recently ordered a BBS02 which should arrive soon. An external ASI low power controller will be used instead of the internal controller. I will also add a temperature sensor to the motor.
Which maximum phase current do you recommend for the BBS02? At which motor temperature should foldback/cutoff be done? (maybe some people using the BBSHD with built-in temperature sensor could help with that)

Are there any mods that can be done to improve the heat dissipation of the BBS02?
 
I've heard some weird stories about the nylon gear melting on the BBS02. According to this thread https://electricbike.com/forum/forum/main-forum/diy-discussion/6734-karl-was-right the nylon gear gets so weak that it breaks at 60C, that seems really low to me...
Seems like the same guy also limited the battery current to 18A, I'm not sure what that would translate to in phase current, maybe your controller got field-weakening which probably would allow you to push it further.

I got a BBSHD (with a BAC855) and I don't know about the RPM of the BBS02, but you want to make sure it runs at a higher RPM. When you put a lot of current into them at low speed they heat up a bunch!

I doubt there are any usable mods that can improve the heat dissipation of the BBS02, the weakest link appears to be that nylon gear. Keeping the motor relativity clean and allow wind to blow on it will help.
But if we talk unreasonable mods there are plenty, like adding a heatsink or maybe even watercool it!
 
Fins.JPG
Extruded aluminum heat sink fins made for Raspberry Pi

My FIN reference : Justin Le analysis of the mid drive
https://endless-sphere.com/forums/viewtopic.php?f=2&t=100461
 
Stealth_Chopper said:
Fins.JPG
Extruded aluminum heat sink fins made for Raspberry Pi

My FIN reference : Justin Le analysis of the mid drive
https://endless-sphere.com/forums/viewtopic.php?f=2&t=100461

Woh, that's amazing! Loving the modding. 8)
Rip your leg if you fall tho. :shock:
 
Wrong motor to use an external controller.
 
Thank you for the replies. I am still waiting for the motor. I think I will definitely add thermal compound, but not sure if I will also do the heatsink mods.

fja2 said:
I got a BBSHD (with a BAC855) and I don't know about the RPM of the BBS02, but you want to make sure it runs at a higher RPM. When you put a lot of current into them at low speed they heat up a bunch!
I will use a 52V battery and chose the BBS02 because it has slower RPM than the BBSHD, so I can keep up with pedalling. The ASI controllers have field weakening of course, but it's not necessary in this case because RPMs would be too high to keep up with.

tomjasz said:
Wrong motor to use an external controller.
Why? I would say an ASI BAC555 is superior to the stock controller. I am using it to make it run smoother using FOC control, and because there are lots of options to set it up how i like it. The plan is not to push more power through it. I read many stories about failure of the internal stock controller, too.
 
The BBS02 motors are not any where as tough as a BBSHD. But hey, what do I know after supporting BBSxx customers for more than six years.
 
I still don't get it why an external controller should be a bad idea on this motor.
I am not planning to run more amps through it than stock, cooling should be way better than on an internal and I read a lot about controller failures with the stock controller probably due to overheating and high failure rate when used with 52V batteries.
 
tomjasz said:
The BBS02 motors are not any where as tough as a BBSHD. But hey, what do I know after supporting BBSxx customers for more than six years.

Mine (now entrusted to other hands) has been fine except for the wheel speed sensor and the pedal sensor. I think it's worth it for better Q factor, chainline, and chain/cassette lifespan-- if you don't need the extra power BBSHD offers.
 
Well,
I don't quite understand everything, but I believe that I limit the power whenever required during every ride as I select the PAS level, (1 ) - (9)

OK if you settle for less voltage power and capability than you paid for, it's up to you.
I bought the unit to save space, avoid interferences, chain line problems, and complexity, avoid mounting and wiring a controller.
However: It goes FAST when required.

Heat rejection must occur at every power level, and poor heat rejection remains unchanged without modification.
Heat sink fins are a common 'bolt on' accessory for high performance RC cars, wrapping around the steel cases of those GHMs
The BBSHD added big thick fins and mass in the cases and other components to overcome excess heat.
I have not read that the BBSHD needed any additional thermally conductive potting which transmits the heat to the cases.

Adding mass is easy and heavy and 'grows' the whole unit, incurring chain line and offset design challenges.
You do know that the current production BBSO2 unit has an improved and effective built in thermal overload to shut down system?

I monitor the motor system temperature with a 'fish tank' ( 2 for $6 ) thermistor taped to the top of the unit.
TEMP.JPG

hias9 said:
I still don't get it why an external controller should be a bad idea on this motor.
I am not planning to run more amps through it than stock, cooling should be way better than on an internal and I read a lot about controller failures with the stock controller probably due to overheating and high failure rate when used with 52V batteries.
 
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