Apples to Apples? Bosch vs. Bafang Ultra

[Stefan Mikes]

Why shall it be limited? Ultra or not? Archon controller I hear so much about?

 

[McCorby]

What conjecture are you talking about? This is quite a fundamental concept in Electromagnetics and practice follows theory very precisely in this field.

I don't know what your background is but I actually did take electromagnetics class during my bs years that is why I am familiar with these concepts.

I am not going into details on flux density here, if you are curious and genuinely want to learn google should be a good place to start.

Regarding motor efficiency:
You said - “But more importantly larger electric motors are simply more efficient due to having thicker coils, larger core size etc.. So given the same controller, Bafang ultra will be more efficient than a mainstream like Bosch, Brose etc. for the simple reason that it has a larger volume and contains more copper.”

For a given application, such as ebikes, a larger motor definitely does not automatically equate to it being more efficient. For example, a larger motor operating at 50% of its rated power will typically be much less efficient than a smaller motor (of similar design) operating at 90% of its rated power under the same load case. This is why I have asked you to show me data/information that backs your claims that the Bafang motor is more efficient and thermally superior to the smaller motors. You obviously know something about their designs that I don’t.

With that said, how often is a typical Ultra motor actually running at or near its rated power level? For the typical rider, I’m guessing not all that often. So under “normal” operating conditions (i.e. cruising down the bike path at 15-20mph), it is most likely being operated in an output range where it is actually not all that efficient compared to the big four operating under the same conditions.

Regarding thermal management:
You said - “Another important point is heat dissipation , more mass means better heat dissipation so an Ultra will tolerate heat better than the smaller counterparts.”

Producing power results in generating heat. In simple terms, the more power you produce, the more heat you will generate....so it only reasons that the Bafang will need to dissipate more heat than a motor that produces less power. Again, what information do you have that the big four motors are not able to adequately dissipate the heat that they generate? Do you think them being lighter means they are unable to adequately dissipate the heat they generate? Also, adding mass is not the only means for effective thermal management.

In the same vein, you said - “Second the mainstream mid drives will dial back when put consistently under their peak power output for a prolonged amount of time, my Bosch cx does it”.

For thermal protection, I would think Bafang does this as well. I would sure hope so anyway. That’s just sound design practice. My Shimano E8000 has thermal protection as well. I have never had it go active though and I ride in a very hilly area.

 

[Stefan Mikes]

For thermal protection

I was riding my Brose TF (Specialized 1.2s) motor for one and half hour in 100% Turbo mode. It had only several seconds by the end of the ride to get into the "yellow zone" at 50 C.

"Bigger motor" = heavy motor. "Powerful motor" = big battery, even more weight. I'm really fed up with the "Bafang Fast & Furious".

 

[reed scott]

I was riding my Brose TF (Specialized 1.2s) motor for one and half hour in 100% Turbo mode. It had only several seconds by the end of the ride to get into the "yellow zone" at 50 C.

"Bigger motor" = heavy motor. "Powerful motor" = big battery, even more weight. I'm really fed up with the "Bafang Fast & Furious".

You just cannot help yourself can you Stefan? I've been bombing around with my Bafang and a 48 volt 17Ah battery for three days ( not all day I admit ) doing exploits and I finally got the battery below 60% an hour a ago. If my keister could take it I am sure I could do sixty miles on this puppy in eco 3. Screw the weight.

 

[Stefan Mikes]

I've been bombing around with my Bafang and a 48 volt 17Ah battery for three days ( not all day I admit ) doing exploits and I finally got the battery below 60% an hour a ago

It's so funny no Bafang rider can show their exploits on Strava.

 

[Gionnirocket]

I was riding my Brose TF (Specialized 1.2s) motor for one and half hour in 100% Turbo mode. It had only several seconds by the end of the ride to get into the "yellow zone" at 50 C.

"Bigger motor" = heavy motor. "Powerful motor" = big battery, even more weight. I'm really fed up with the "Bafang Fast & Furious".

It's so funny no Bafang rider can show their exploits on Strava.

Strava app... another "Look at Me" from the Pompous & Obnoxious.
Believe it or not... Not everyone cares to count cadence and post personal achievements

 

[reed scott]

It's so funny no Bafang rider can show their exploits on Strava.

Stefan Stefan Stefan.... If I ever start advertising my riding habits thru Strava or any other ride app .... you have permission to shoot me.

 

[Johnny]

I was riding my Brose TF (Specialized 1.2s) motor for one and half hour in 100% Turbo mode. It had only several seconds by the end of the ride to get into the "yellow zone" at 50 C.

"Bigger motor" = heavy motor. "Powerful motor" = big battery, even more weight. I'm really fed up with the "Bafang Fast & Furious".

1.5 hours at peak output ? I don't think so since Brose peaks around 600W, if you were peaking that would translate into 1100-1200wh given %70-80 efficiency. Isn't your battery around 600wh ? What was your average motor output during that ride ?

 

[Johnny]

For a given application, such as ebikes, a larger motor definitely does not automatically equate to it being more efficient. For example, a larger motor operating at 50% of its rated power will typically be much less efficient than a smaller motor (of similar design) operating at 90% of its rated power under the same load case. This is why I have asked you to show me data/information that backs your claims that the Bafang motor is more efficient and thermally superior to the smaller motors. You obviously know something about their designs that I don’t.

This statement is false. First of all it is not that straightforward many factors come into play in terms of efficiency. While these motors will give their highest efficiency around %80 of their maximum rated load(this can change and design dependent) at %50 they are still fairly efficient. As a matter of fact a 2kw motor at %50 load can easily be more efficient than a 1kw motor at full load. Below is a chart from an old study by department of energy on motor efficiency vs load percentage.

At %50 the 1.5-5hp motor is close to its peak efficiency while the 0-1hp one is actually lower than that at its %90 load. As the motor gets more powerful/larger, its efficient power band actually increases. Even if they operate at the same efficiency, the generated heat will be the same for the same power output and the larger motor will dissipate it better and stay cooler, smaller motor will lose efficiency as it overheats...
Of course this doesn't mean you can use a 100hp motor for an ebike, yes it will be very inefficient since you will be running it at .

 

[Ravi Kempaiah]

@McCorby and @Johnny ,

It's quite difficult to compare the Bosch Gen 4 system to a Bafang ultra system.
Power and efficiency can be compared only if the motor construction (armature), windings and controller etc. all are identical.
Also, discussing power without considering RPM is not going to lead to meaningful discussion. Justin at Ebikes.ca has a very detailed article on how power ratings can be highly misleading.
https://ebikes.ca/learn/power-ratings.html

Many of those insights are relevant to mid-drives as well. Mid-drives employ gearing ratio within the motor and also between the motor and the rear wheel.

1. Bosch Gen 4 system uses magnesium housing and the electronics have been overhauled for efficiency.
   
   
   
   The controller algorithm can also be different. For example, with the same hardware, Bosch Gen4 cargo line has a slightly different behavior compared to the Gen4 performance line.
   So, the motors can be setup to behave differently. So, the gearing at the wheel can play a role as well
   
   
2. There are various videos on YouTube where someone installed a Phaserunner controller for the ultra and the motor was running cooler and more efficiently.
   Some people who are using the Innotrace controller also report better efficiency. So, it means the controller makes a significant difference as well.
   
   
   

   Emtb - Bafang Ultra G510 3500W Innotrace controller

   My fatbike is still going strong https://endless-sphere.com/forums/viewtopic.php?t=96212 But it was time to build a new bike Got this Seroxat frame from Salto bikes http://www.salto-bike.com/ecp_view.asp?id=653 This frame is meant to fit a "smaller batterycase designed for 14S4P cells...

   endless-sphere.com
   
   
3. Gearing within these motors is quite different.
   I believe the ultra motor has an 18:1 ratio as quoted in this article: https://www.electricbike.com/bafang-ultra-max/
   Bosch has a different gearing ratio.
   
   
4. The armature size is also very different. The rotational mass of rotors is quite different if you just look at the visuals.

Considering all these, it is not accurate to state that one system is more efficienct than the other.

 

[ElevenAD]

Which is illegal in the U.S., too. I know many people think "if they don't catch me, no harm done" but come on...

Yes, they are large and in charge !

man the Ultra is over built! is that other motor a BBS02?

 

[ElevenAD]

Which is illegal in the U.S., too. I know many people think "if they don't catch me, no harm done" but come on...

i get what your saying why make it easy to get an illegal bike?it could be opening a can of worms,we will see but for now the Police dont seem to care( for the most part) as long as your riding responsibly,its not all doom and gloom, i have only gone past 28mph 3 times in the past 2 years so not everyone with an Ultra is going bring negative attention to biking. Tesla S does 155mph, speed limit is 65mph but its cool because we know every Tesla owner is not going to drive around at 155mph.....and for the select knuckle heads that do,well....

 

[Stefan Mikes]

1.5 hours at peak output ? I don't think so since Brose peaks around 600W, if you were peaking that would translate into 1100-1200wh given %70-80 efficiency. Isn't your battery around 600wh ? What was your average motor output during that ride ?

I see @Johnny you have an analytical mind, so I have all the answers for you.

1. I had two 604 Wh (nominal) batteries with me;
2. I went into the 100% Turbo mode after 6 min 56 s when I rode onto an open road;
3. After 33 min 39 seconds of Turbo ride, I had a stop for 31 minutes;
4. Meanwhile, I replaced the battery with 231 Wh left with a spare that initially had 583 Wh;
5. Then I continued the ride for 39 min 52 s, all in 100% Turbo mode.

Below, there are filtered analytical data from BLEvo app for Specialized e-bikes. I think BLEvo reports not the "Motor Power" but rather "Power Draw from the Battery". I estimate the efficiency of the Brose TF/Specialized 1.2s motor to be at 78% (as the actual peak power of that motor is 520 W).

If you're interested with the Excel file, I can share it with you.

P.S. Do Bafang motors provide such data?

 

[Gionnirocket]

I see @Johnny you have an analytical mind, so I have all the answers for you.

1. I had two 604 Wh (nominal) batteries with me;
2. I went into the 100% Turbo mode after 6 min 56 s when I rode onto an open road;
3. After 33 min 39 seconds of Turbo ride, I had a stop for 31 minutes;
4. Meanwhile, I replaced the battery with 231 Wh left with a spare that initially had 583 Wh;
5. Then I continued the ride for 39 min 52 s, all in 100% Turbo mode.

Below, there are filtered analytical data from BLEvo app for Specialized e-bikes. I think BLEvo reports not the "Motor Power" but rather "Power Draw from the Battery". I estimate the efficiency of the Brose TF/Specialized 1.2s motor to be at 78% (as the actual peak power of that motor is 520 W).
View attachment 75230

If you're interested with the Excel file, I can share it with you.

P.S. Do Bafang motors provide such data?

Your data has obvious flaws

 

[TForan]

man the Ultra is over built! is that other motor a BBS02?

Yes

 

[TForan]

I'm really fed up with the "Bafang Fast & Furious".

That is so sad. They are freakin' bicycles ! We can discuss the different attributes but I don't think getting "fed up" is healthy. I'm on my fourth year on my Ultra powered fat bike and still enjoy it, but next spring , when I look for a bike for my wife, I might go with the big four because she doesn't need all that torque for a cruiser. Just buy what fits your needs and don't get so worked up.

 

[Gionnirocket]

That is so sad. They are freakin' bicycles ! We can discuss the different attributes but I don't think getting "fed up" is healthy. I'm on my fourth year on my Ultra powered fat bike and still enjoy it, but next spring , when I look for a bike for my wife, I might go with the big four because she doesn't need all that torque for cruiser. Just buy what fits your needs and don't get so worked up.

I agree ... Bosch and the big four are geared more towards women.

But then again... why not save a few dollars and just castrate the Ultra with a little tuning?

 

[TForan]

I agree ... Bosch and the big four are geared more towards women.

But then again... why not save a few dollars and just castrate the Ultra with a little tuning?

That would be like disconnecting the back four barrel on a dual quad setup.

 

[Gionnirocket]

That would be like disconnecting the back four barrel on a dual quad setup.

Perhaps... But a bit more cost effective and works just as well if you are happy with the Ultra bike in all other aspects.
In experimenting with tuning I've tried a variety of settings to experience the differences and you can definitely tame it safe enough for even a child to not be overwhelmed.
You could then save both profiles so that you could easily switch between and if you had a need to borrow the bike in the future... it wouldn't feel like you're on a ride to grandma's house

 

[TForan]

Perhaps... But a bit more cost effective and works just as well if you are happy with the Ultra bike in all other aspects.
In experimenting with tuning I've tried a variety of settings to experience the differences and you can definitely tame it safe enough for even a child to not be overwhelmed.
You could then save both profiles so that you could easily switch between and if you had a need to borrow the bike in the future... it wouldn't feel like you're on a ride to grandma's house

I'm happy with the Ultra because I have a fat tire bike that inherently has more resistance and drag, therefore it needs the torque. I rode a Felt Outfitter with a Bosch and it simply didn't have enough for that heavy of a bike and it was $2000 more than my Biktrix. Otherwise there's lots of good choices in motors. One size does not fit all.