Bafang H640
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AHicks
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Re: the H630, curious that they rate it with a range of 750-1000w. With 90nm of torque, it sounds like it may be on the low side of a 1000w rated motor. For comparison, the MAC 12t is rated 1000w and makes 106nm.
There's no mention of drop out width here either. I wonder if these are all 135mm?
There's no mention of drop out width here either. I wonder if these are all 135mm?
AHicks
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- USA
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- Snow Bird - Summer S.E. Michigan, Winter Gulf Coast North Central Fl.
Been looking all over for the 135mm (or so) drop out version of this motor. Thanks! Now to source it...
Regarding the difference in torque (MAC 12t vs 1000w Bafang), I believe I have that mystery under control. I believe it's about how the motors are wound, which can be seen with the difference in rated rpms. The MAC 12t torque monster is rated at 250 rpm or so if memory serves me. The 750/1000w Bafang is rated for a little over 400. A motor wound for low speed is going to have more starting torque, where a motor wound for speed will have less.
Check out the Grin graph for the MAC 12t and 8t. Clearly the 12t has way more starting torque as compared to the 8t, but that's NOT the end of the story....
Check out "graph" at the lower left of the screen for the difference in rpm's 12t vs. 8t. -Al
ebikes.ca
Regarding the difference in torque (MAC 12t vs 1000w Bafang), I believe I have that mystery under control. I believe it's about how the motors are wound, which can be seen with the difference in rated rpms. The MAC 12t torque monster is rated at 250 rpm or so if memory serves me. The 750/1000w Bafang is rated for a little over 400. A motor wound for low speed is going to have more starting torque, where a motor wound for speed will have less.
Check out the Grin graph for the MAC 12t and 8t. Clearly the 12t has way more starting torque as compared to the 8t, but that's NOT the end of the story....
Check out "graph" at the lower left of the screen for the difference in rpm's 12t vs. 8t. -Al
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AHicks
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A perfect example of 'druthers, no?
May I remind you of my weight, and the fact that rarely do I have power on at speeds over 15mph?
12t suit's me perfectly. Huge power on tap, and very efficient at speeds I travel most frequently.
I agree. The 8t, or even the 10t Mac is more about guys running at 15mph+. That ability is nice, but how often do you REALLY ACTUALLY find yourself at speeds like that? Put it in percentages!
12T suits my purposes best 90% or more of the time. If you can get an 8 or 10t Mac that will satisfy your purposes at a percentage that high, I'd say go for it! Just consider how much power you're using while doing that.....
May I remind you of my weight, and the fact that rarely do I have power on at speeds over 15mph?
12t suit's me perfectly. Huge power on tap, and very efficient at speeds I travel most frequently.
I agree. The 8t, or even the 10t Mac is more about guys running at 15mph+. That ability is nice, but how often do you REALLY ACTUALLY find yourself at speeds like that? Put it in percentages!
12T suits my purposes best 90% or more of the time. If you can get an 8 or 10t Mac that will satisfy your purposes at a percentage that high, I'd say go for it! Just consider how much power you're using while doing that.....
AHicks
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Too, I can assure you that the 12t will do 28mph pretty easily. It has no trouble cracking 30mph in a sprint.
Further, due to the motor being buried deep in that case with absolutely no cooling available, it's going to build heat quickly no matter how many turns of wire are on the armature. Even though the 8t and 10t are set up for faster speeds, there has been nothing done to add extra cooling to allow that extra speed for any distance to speak of. A mid drive is no different. You need a direct drive for that kind of an application.
Use Grin's chart to add a load, and see how long it takes to heat up a motor under different conditions.... -Al
Further, due to the motor being buried deep in that case with absolutely no cooling available, it's going to build heat quickly no matter how many turns of wire are on the armature. Even though the 8t and 10t are set up for faster speeds, there has been nothing done to add extra cooling to allow that extra speed for any distance to speak of. A mid drive is no different. You need a direct drive for that kind of an application.
Use Grin's chart to add a load, and see how long it takes to heat up a motor under different conditions.... -Al
AHicks
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- USA
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- Snow Bird - Summer S.E. Michigan, Winter Gulf Coast North Central Fl.
Another thought-
Consider the motor rpm requirements as related to wheel size. For similar perfomance using a smaller diameter wheel (say a 16"-20"?) I'm going to want a higher rpm motor to make up for the smaller diameter - as compared to the rpm's required for a 26" or bigger wheel.
Consider the motor rpm requirements as related to wheel size. For similar perfomance using a smaller diameter wheel (say a 16"-20"?) I'm going to want a higher rpm motor to make up for the smaller diameter - as compared to the rpm's required for a 26" or bigger wheel.
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