Bafang bbs01b 250w 36v or 48v?

[ibra2672]

Hello. I was looking to buy my first mid drive motor and found 2 versions of the Bafang bbs01b listed on Amazon. They have the 36v 250W version with a 15 Ampere controller and the 48v version with a 12 Ampere controller. I was wondering which of these 2 is the best one to get. Meaning the one with the most torque and higher max speed.
I also wanted to ask if it's possible to tune it with software in order to boost the power or maybe hook up a stronger external controller to it.

 

[amberwolf]

What do you need the system to do for you, under what specific riding conditions?

If your needs exceed what the mechanics of the drive can do, then more power may just break it (and will wear it out faster even if it doesn't).

You might end up needing one of the heavier-duty middrives instead of trying to upgrade this one, if your needs are high enough.

 

[Chalo]

If you want more power or max speed than BBS01, get BBS02. That problem has already been solved.

 

[ibra2672]

Thanks for the answers. I'm considering the bafang bbs02 750w at the moment.

 

[ibra2672]

Was just wondering if there's even a difference between the 2 models? If there is then what is it? If there isn't, then why did bafang bother to make 2 versions?

 

[amberwolf]

Was just wondering if there's even a difference between the 2 models? If there is then what is it? If there isn't, then why did bafang bother to make 2 versions?

Perhaps your question refers to some other property of the systems, but doesn't the first post in your thread (whcih I moved this post to) already contain your answer? (relevant line quoted below)

They have the 36v 250W version with a 15 Ampere controller and the 48v version with a 12 Ampere controller.

 

[ibra2672]

I was just curious if there were any other differences between the 2 versions.
In the end i bought a 250w 48v bafang kit cuz of the law that limit speed and power (EU e-bike laws suck ).

 

[ibra2672]

The fact that i was considering the 750w is because there a 12° (average) 270m long slope i wanted to climb. That slope has some points where it reaches 17° and there a critical point of 20°. Do you thing the 250w bafang can make it? I have a front 44t chainring and a 7 speed freewheel 11t to 34t

 

[amberwolf]

Just to be sure, since it is a large difference in calculations, are you certain it is degrees, not percent?
\

If you know the slopes, wheel size, bike weight plus rider and anything you carry, and any headwinds you'll encounter, you can use the http://ebikes.ca/tools/simulator.html to play with various configurations of systems to see how much power it will take to accomplish a specific job, using the "middrive" option and the various gearing you have available. If it doens't have the motor you want to use in there already, you can just pick a small hubmotor and a controller of appropriate current limit (or use the custom option to create one with that limit), to do the guesstimates with. It's not perfect, but it will get you in the ballpark.


This is a basic slapped-together comparison sim of 20 degrees vs 20% with the closest gearing it has available to your best low-gear combination, but not knowing your system/rider weight or other parameters I left those as defaults.
https://ebikes.ca/tools/simulator.html?mid=true&motor=MG310_STD&cont=cust_12_25_0.03_V&hp=0&grade=20&cont_b=cust_12_25_0.03_V&motor_b=MG310_STD&hp_b=0&mid_b=true&grade_b=11&bopen=true&batt=B4814_EZ&batt_b=B4814_EZ&tr=34&tr_b=34
The table doesn't come out aligned below but you can see the huge difference in the two--the system A on 20 degree slope literally can't even move, while the 20 percent slope (a bit more than half of 20 degrees) is able to reach about 12kmh on throttle alone, no human power. System A shows virtually no power usage but that's wrong because it would actually be at absolute max limits trying to move until it overheated or the controller shutdown to protect itself. The overheat warning time/etc here are not valid because those are for the little hubmotor I chose as I didn't see the BBS system listed.
Graph Syst A Syst B
Wheel Torq 41.5Nm 39.4Nm
Mtr Power 19W 411W
Load 31W 411W
Efficiency 12.7% 70.9%
RPM 7.2 rpm 161.3 rpm
Electrical Syst A Syst B
Mtr Amps 24.9A 24.0A
Batt Power 151W 580W
Batt Amps 3.1A 12.0A
Batt Volts 49.4V 48.4V
Performance Syst A Syst B
Acceleration -2.68 kph/s -0.01 kph/s
Consumption 274.6 Wh/km 46.7 Wh/km
Range 2.5 km 14 km
Overheat In 13 minutes 14 minutes
Final Temp >250 °C >250 °C



It is possible that the motors are a differnet winding, so that they spin the same speed at their respective max voltages. There is probably info about that in one of the many BBS01b threads (I have not looked at most of them in years, so I don't know for sure).

 

[ibra2672]

Oh my goodness, i wasn't expecting such a detailed answers. Thx a lot. I really appreciate it.
Btw they are degrees and not a percentage (about a week ago i didn't even know that there was a difference between degrees and percentage :lol: Lol)
My bike weights 19.7kg and the battery is 7kg. The bafang kit is 4kg and my body weight is 107kg. So the total weight is 137.7Kg. The tires of the bike are 20" x 4". The battery is 48v 28.8 Ah with a 40Amp BMS.

 

[SUPERJC]

we compared to several owners of BBS01(b)
according to our measurements bbs01(b) 36V and 48V it is the same motor (same rpm/V crankset = 2.35 without load)
2.35 x 42V = 98.7 rpm
The difference is only the controller

 

[amberwolf]

Btw they are degrees and not a percentage

Then at least the worst-case is probably too steep for the system's available power and your present gearing. You can change your front chainring to a smaller one, which will lower your top speed but give you more torque. How small you need to go depends on your system weight and wheel size, etc (play with the simulator to see).

My bike weights 19.7kg and the battery is 7kg. The bafang kit is 4kg and my body weight is 107kg. So the total weight is 137.7Kg. The tires of the bike are 20" x 4". The battery is 48v 28.8 Ah with a 40Amp BMS.

Using the closest presets to those in the simulator link I did above, it actually has worse results (because of the extra weight, most likely, as my original only used the default 100kg), it only makes it about 6kph on the lesser slope and still can't even start up the steep one.

Graph Syst A Syst B
Wheel Torq 41.5Nm 41.2Nm
Mtr Power 12W 286W
Load 21W 286W
Efficiency 8.7% 63.9%
RPM 4.6 rpm 107.4 rpm
Electrical Syst A Syst B
Mtr Amps 24.9A 24.9A
Batt Power 144W 447W
Batt Amps 2.9A 9.1A
Batt Volts 49.6V 49.0V
Performance Syst A Syst B
Acceleration -3.00 kph/s -0.00 kph/s
Consumption 522.8 Wh/km 70.4 Wh/km
Range 2.1 km 15 km
Overheat In 13 minutes 13 minutes
Final Temp >250 °C >250 °C


Going to a 30t chainring on the front (lowest preset in the sim) gives 9kph on lesser slope, still nothing on the steep one.


Just to repeat, this is not an accurate sim of the BBS01b, just a slaptogether guesstimate at about the same power level. The actual system may work better, or worse, or the same. It's really just to show that the total power available in the system isn't enough to handle the load by itself.

 

[ibra2672]

Thx a bunch for the replies. :thumb:
I guess my only solutions are either a 750w bafang or a smaller chainring.

 

[Chalo]

Thx a bunch for the replies. :thumb:
I guess my only solutions are either a 750w bafang or a smaller chainring.

Using a smaller than 42T chainring on BBSxx results in such poor chainline that the lowest gears may not work at all. I suggest using 42T and 750W.

Another approach that you can use with or without the above would be to switch to a Microshift Acolyte shifter, derailleur, and 12-46 cassette. It's the most cost-effective way to get into "one-by" gearing with low ratios.

 

[ibra2672]

Thx for the suggestion. The hub of my wheel is a freewheel hub. So that means I'd have to change hub to be able to mount a cassette, wouldn't I?

 

[Chalo]

Thx for the suggestion. The hub of my wheel is a freewheel hub. So that means I'd have to change hub to be able to mount a cassette, wouldn't I?

That's one way (the best way) to do it. I've seen freewheels as big as 42 teeth, but only in 8 and 9 speed formats.

Unless your existing hub is special, even narrower 7 speed freewheel spacing predisposes the axle to bend under normal riding loads (which is why cassette hubs were originally developed). So switching to a cassette hub will give you a more reliable wheel as well as better gearing options.

 

[ibra2672]

:thumb: :thumb: :thumb: