Difference between 250w and 350w motor

[saneagle]

Look at the comparison between the BPM and the much smaller G370. Everything is nearly identical throughout the rpm range -speed, power and torque

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[Peter.Bridge]

Look at the MXUS efficiency curve. It has a big dip just before maximum efficiency. That's not normal. If it had the same shape as the BPM, it would have made more power. I would have wanted that one tested again, if that's what they did, otherwise they need to sort out their prediction algorithms unless someone can explain why it should be like that.

Also, look at the torque. How can the MXUS make 35% more torque than the BPM. I don't believe that it can by that much.

The BPM (despite having a 5kph higher no load maximum speed) also has a slightly higher hill speed ( and output power and efficiency) than the much newer , very lightweight G370.

Eta - you can see it more clearly on the heavier G60 fatbike motor vs lightweight G370

 

[saneagle]

View attachment 59787

The BPM (despite having a 5kph higher no load maximum speed) also has a slightly higher hill speed ( and output power and efficiency) than the much newer , very lightweight G370.

Eta - you can see it more clearly on the heavier G60 fatbike motor vs lightweight G370
View attachment 59788

Wrong version of the G370. Use the standard one, which has nearly the same speed as the BPM. It's in my link above. Whatever, you can still see that the slower motor always makes more torque at low speed. In the above graph the smaller one wins all the way up to 14 mph.

 

[Peter.Bridge]

Wrong version of the G370. Use the standard one, which has nearly the same speed as the BPM. It's in my link above. Whatever, you can still see that the slower motor always makes more torque at low speed. In the above graph the smaller one wins all the way up to 14 mph.

That's the 2.5kg G310 rather than the 1.6kg G370. But let's compare the G310 with the much heavier G60 fatbike motor

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[Sturmey]

View attachment 59786

Here - the xf07 has a no load max speed of 30km/h and the BPM a no load max speed of 39 km/h. However up a 10% hill the xf07 only generates 323w and reaches 13.8 kph compared to the BPM that generated 391w and reaches 15.8 kph for the same input voltage / current from the controller. The BPM shows 70.6% efficiency vs 58.4% for the xf07 - this is how I understood it worked - bigger motors are more efficient at lower revs (going up a steep hill)

Re The graph above, you have set the controllers with a maximum phase current limit of 30Amps and this is putting a limit on your BPM torque and is causing the torque blue line to abruptly level off horizontally as RPM drops. If you change you controller phase current limit from 30A to 70A as I have below to remove the phase limit, you will correct this as I have below.
This then explains the problem with the BPM low torque limit with your model. A higher rpm motor usually has more strands but less turns (all other things been equal) and needs more phase current which you put a 30A limit on..... Phase current is not the same as battery current and increases above battery current as the rpm drops below the peak power point on the curve.
PS. The reason I originally used the BPM as a comparison is because I thought it might come close to the xf15 which I upgraded to which is not modeled. Incidentally, what motor do you have at present?

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Our ebike motor simulator allows you to easily simulate the different performance characteristics of different ebike setups - with a wide selection of hub motors modeled, and the ability to add custom batteries and controllers and set a wide variety of vehicle parameters you'll be able to see...

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[Sturmey]

Look at the comparison between the BPM and the much smaller G370. Everything is nearly identical throughout the rpm range -speed, power and torque

Motor Simulator - Tools

Our ebike motor simulator allows you to easily simulate the different performance characteristics of different ebike setups - with a wide selection of hub motors modeled, and the ability to add custom batteries and controllers and set a wide variety of vehicle parameters you'll be able to see...

ebikes.ca

The G370 as a small motor performs well(I think) because they run the internal motor very fast and reduce the speed by something like 11:1 as compared to 5:1 with the BPM and xf15. But I wonder how does it compare to the BPM on long runs with 20 minutes continuous hill climbs in terms of overheating and durability? The 'Final Temp' on the simulator puts me off.
One of the attractions of mxus motors is that are very cheap and easily available at present and the xf15 upgrade seems (and has been) a good option.(so far so good)

 

[Peter.Bridge]

Re The graph above, you have set the controllers with a maximum phase current limit of 30Amps and this is putting a limit on your BPM torque and is causing the torque blue line to abruptly level off horizontally as RPM drops. If you change you controller phase current limit from 30A to 70A as I have below to remove the phase limit, you will correct this as I have below.
This then explains the problem with the BPM low torque limit with your model. A higher rpm motor usually has more strands but less turns (all other things been equal) and needs more phase current which you put a 30A limit on..... Phase current is not the same as battery current and increases above battery current as the rpm drops below the peak power point on the curve.
PS. The reason I originally used the BPM as a comparison is because I thought it might come close to the xf15 which I upgraded to which is not modeled. Incidentally, what motor do you have at present?

Motor Simulator - Tools

Our ebike motor simulator allows you to easily simulate the different performance characteristics of different ebike setups - with a wide selection of hub motors modeled, and the ability to add custom batteries and controllers and set a wide variety of vehicle parameters you'll be able to see...

ebikes.ca

Ah, thanks for explaining, I had for some reason thought the max phase current set to 2*max battery current was appropriate

I have an xfO8c (in a 700c wheel), a Bafang g020 otherwise known as h405 ? (In a 26" wheel) and an 1.6 kg akm74 in a 20 inch wheel (which seems to have nearly identical properties to the 1.6kg Bafang g370 in a 27.5" wheel

Motor Simulator - Tools

Our ebike motor simulator allows you to easily simulate the different performance characteristics of different ebike setups - with a wide selection of hub motors modeled, and the ability to add custom batteries and controllers and set a wide variety of vehicle parameters you'll be able to see...

ebikes.ca

)

The simulator seems to show a heavier duty motor with the same no load max speed, fed the same current by a controller, will have greater efficiency and a faster speed up a steep incline than a smaller motor (which is the impression that I had before)