Bafang motor upgrade comparison

[JTK77]

I went ahead and bought the "upgrade" motor for my RadMini. It wasn't a need, and I bought it partly out of curiosity, but it provided a nice opportunity for testing and comparison.
If you spend any time on e-bike websites and forums, I'm sure you've heard the claim that Rad motors are not "true" 750 watt motors, and you need to buy an upgrade. This idea started in an online forum, then became popular through YouTube. Oddly, most opinions on this are based on looks, and while there are many things you can determine by looks, electrical specifications are not one of them. That being said, I do like the motor and will be keeping it. It's a high quality unit and worth the money, depending on your needs.


Side by side comparison



The Rad and upgrade motors do have some differences in design. Most notable is the magnet shell. This is narrower on the Rad motor, and wider on the upgrade. What does this mean? It means the shell is wider. What seems to throw people off is that the Rad motor has this empty space between the stator windings and the mounting plate. The upgrade motor does not have this space... or does it? It turns out the upgrade motor also has an empty space. It's just in a different location.





Although it seems the upgrade motor has bigger windings, in reality, it does not. The stator coils are the same size, as are the magnets.

The installation of the new motor itself went fine, with only one hitch: I was using a cast bit to remove the T-20 Torx head screws with anti-tamper pins, and the bit shattered. To avoid that, I purchased a forged Craftsman folding driver set, and used a butane mini-torch to soften the Locktite for the screws. The only settings changes required to the controller display was changing the speed pulse sensor (P2) from five to six.

Doing the math

I was a bit surprised when I could not get the motor specifications, so I had to do some testing on my own. Below are the results.

Stock Rad motor
Top speed: 23 mph
22 inch wheel RPM at 23 mph: 351.592
Motor RPM at 23 mph: 1757.96  (351.592 x 5)
Motor rating:  32.55 kV (approximate - electronically limited)
-------------
Bafang upgrade motor
Top speed: 27.4 mph
22 inch wheel RPM at 27.4 mph: 418.85
Motor RPM at 27.4 mph: 2094.26  (418.85 x 5)
Motor rating: 38.78 kV

The Rad kV rating is an estimate because it has a built-in limiter that starts reducing power electronically, so the motor is not free to reach it's natural RPM. The Bafang upgrade motor does not have this limiter, and this was one of the reasons I wanted to try it out. You can see the difference on the wattage being used at top speed: The Rad motor is only pulling a couple hundred watts at top speed, even though over a thousand watts is available, while the upgrade motor actually is pulling over a thousand watts at top speed.

Acceleration and hill climb tests

Tests with both motors were done on a RadMini 4 with dual batteries and a 35 amp controller, battery voltage at 54.3 volts, and the tires at 12 PSI. Performance would be better with more air in the tires, but since the first tests were done at low pressure, I kept them the same.

Original Rad motor 0 to 20 mph: 4.9 seconds
Bafang upgrade motor 0 to 20 mph: 4.9 seconds

Wait, what? You read that right, and I ran the tests multiple times. The motors had the same acceleration times. They are both a blast to ride with the 35 amp controller, with the Rad motor pulling ahead off the line and the upgrade motor catching it.

The hill climb test was a bit more subjective, but basically I drove up an absurd 28% grade berm for a freeway overpass. The Rad motor seemed to have a bit more low RPM torque, getting up without me touching the pedals. The upgrade motor had a little harder time, and although it made it, it was not as confidence inspiring.

In top speed, there was no comparison. The Rad motor can hit 23 mph if you change your settings, but the power starts being electronically reduced above 20. If you are already riding at 20 mph and go full throttle, the response is like "Well, ok, give me a minute" as it gradually gathers momentum on the restricted power. With the upgrade motor, it's prime time, and giving the throttle a full twist at 20 mph responds with the attitude of "Hold my beer!". Yes, it does top out at 27/28 mph because kV x voltage = RPM, but it gets you there decisively.

In conclusion, if you have off road or private areas where you can safely use the extra speed, the Bafang upgrade motor is worth every cent. If you need to keep it locked to 20 mph though, the Rad motor will do the same job and can handle the 1,600 watt power levels fine.

Couple of things here.
Most importantly there are MORE THAN ONE KV VARIANT OF BOTH MOTORS. The 750 is slightly more efficient at high power levels but how that affects performance depends on the kvs and test setting.
Second if you look more closely you find that the windings are actually bigger in 750 vs 500. There is slightly bigger gap (750 vs 500) in output side of the housing but less than you marked on your picture. Also the magnets are comparably longer and weight is more.
When you test low kv vs high kv at same input power you will find torque and topspeed differences (though the 750w has more torque when kvs are the same)  However 750w version enables using higher power slightly more efficient.

[Altema]

Couple of things here.
Most importantly there are MORE THAN ONE KV VARIANT OF BOTH MOTORS. The 750 is slightly more efficient at high power levels but how that affects performance depends on the kvs and test setting.
Second if you look more closely you find that the windings are actually bigger in 750 vs 500. There is slightly bigger gap (750 vs 500) in output side of the housing but less than you marked on your picture. Also the magnets are comparably longer and weight is more.
When you test low kv vs high kv at same input power you will find torque and topspeed differences (though the 750w has more torque when kvs are the same)  However 750w version enables using higher power slightly more efficient.

The windings are bigger in the Rad motor. I've pulled the motors the rest of the way apart and measured them directly. The stator coil windings on the Rad motor are 0.65mm in diameter. On the upgrade motor they are 0.55mm.

The magnets are longer, but not by much. The magnet shell is 14mm wider, but the difference in the magnets is only 5mm. Actual magnet size is 16 x 25mm for the Rad, 16 x 30 for the upgrade motor. We'll see how efficient things are with the new motor. I have not noticed an increase in range yet, but that would be nice.

The biggest takeaway is that the Rad motor is not the villain. It handles all the power you can throw at it, and there is no difference in a drag race to the legal limit. I'd say that, unless you really need to get rid of the internal speed limiter for off road use, changing motors is pointless and makes the bike heavier. Granted, you won't keep up with Super 73's, but you won't have to push your bike up hills either

[JTK77]

Yes. Multistrand winding enables more copper fill. That's why the G060.750 can have thinner coil strand but still faster kv (in this case).
In overall the efficiency increases little but this is mostly beneficial in terms of fewer watts wasted in overheating as copperlosses. The difference naturally increases with more power used and is further effected by the increased copper temperature (increase in R).
I had the 750+52v+35A setup few years back but now running vented G062.1000 at 60v 40A..and going soon to custom 45-50A sinewave and custom 60v 24Ah 150A BT battery.

[Tony]

You think the proper 750 watt motor would be a noticable upgrade over the euro 250 model though ?
Maybe the euro model is a restricted 350/500 motor.

[JTK77]

You think the proper 750 watt motor would be a noticable upgrade over the euro 250 model though ?
Maybe the euro model is a restricted 350/500 motor.

Rad uses only 500w version of G060 motor in all markets. Changing only the motor (to 750) is not so noticable (slight improvement).
Cheapest and effective is to to G062.1000w ( prelaced ) preferably cassette version (DC) + Eggrider.
Depends what you want and at what cost.

[Tony]

I have the 35 amp Controller on order so I understand that should be a good improvement for the euro 250. I was thinking of adding the 750 motor as I would like some extra power for hills especially carrying some cargo. Top speed not really necessary.

[JTK77]

I have the 35 amp Controller on order so I understand that should be a good improvement for the euro 250. I was thinking of adding the 750 motor as I would like some extra power for hills especially carrying some cargo. Top speed not really necessary.

Yes, thats good idea.

[fin_rad]

The Bafang model number is RM G060.750.D 06
Rad controller limits the motor power. The Rad motor internal RPM limiter limits the speed.

Is there any stamps on the motor (inside or outside) where I could identify which model the motor is? Just being curious and interested in learning how the ebike systems work.

[JTK77]

The Bafang model number is RM G060.750.D 06
Rad controller limits the motor power. The Rad motor internal RPM limiter limits the speed.

Is there any stamps on the motor (inside or outside) where I could identify which model the motor is? Just being curious and interested in learning how the ebike systems work.

The meaning of Bafang model markings:
G060 = casing identification
750 = nominal rating
D = freewheel (DC = freehub)
(6) = winding identification (smaller is faster, no it directly equal to KV)

All Power versions within same casing series are swappable.
Rated model not possible to say what from casing as OEM customers can have custom labeling or motor core can ne swapped.
Rad has done both. In the past casing swap (+sticker) and nowadays custom labeling.
KV can ne identified by no load speed (wheel of the ground full throttle) If you have the throttle.

[Tony]

Good information, thank you. 

[springer03]

The Bafang model number is RM G060.750.D 06
Rad controller limits the motor power. The Rad motor internal RPM limiter limits the speed.

Is there any stamps on the motor (inside or outside) where I could identify which model the motor is? Just being curious and interested in learning how the ebike systems work.

The meaning of Bafang model markings:
G060 = casing identification
750 = nominal rating
D = freewheel (DC = freehub)
(6) = winding identification (smaller is faster, no it directly equal to KV)

All Power versions within same casing series are swappable.
Rated model not possible to say what from casing as OEM customers can have custom labeling or motor core can ne swapped.
Rad has done both. In the past casing swap (+sticker) and nowadays custom labeling.
KV can ne identified by no load speed (wheel of the ground full throttle) If you have the throttle.

I just received this same motor RMG06 48V750W(6) from Bolton for my radrover 5 and had noticed the one Electric bike world sells is RMG06 48V750W(7)
would there be a noticeable difference in torque between the two? On hills?

I would have preferred more torque for hills, but would rather not return the one I already have if the difference is minimal and not really noticeable.

(I also do have the 35amp controller on order)
Thanks.

[fin_rad]

The Bafang model number is RM G060.750.D 06
Rad controller limits the motor power. The Rad motor internal RPM limiter limits the speed.

Is there any stamps on the motor (inside or outside) where I could identify which model the motor is? Just being curious and interested in learning how the ebike systems work.

The meaning of Bafang model markings:
G060 = casing identification
750 = nominal rating
D = freewheel (DC = freehub)
(6) = winding identification (smaller is faster, no it directly equal to KV)

All Power versions within same casing series are swappable.
Rated model not possible to say what from casing as OEM customers can have custom labeling or motor core can ne swapped.
Rad has done both. In the past casing swap (+sticker) and nowadays custom labeling.
KV can ne identified by no load speed (wheel of the ground full throttle) If you have the throttle.

Thank you for a good answer again - once more the answer opened more questions... So I will follow the path to learn more about electric motors.

[JTK77]

The Bafang model number is RM G060.750.D 06
Rad controller limits the motor power. The Rad motor internal RPM limiter limits the speed.

Is there any stamps on the motor (inside or outside) where I could identify which model the motor is? Just being curious and interested in learning how the ebike systems work.

The meaning of Bafang model markings:
G060 = casing identification
750 = nominal rating
D = freewheel (DC = freehub)
(6) = winding identification (smaller is faster, no it directly equal to KV)

All Power versions within same casing series are swappable.
Rated model not possible to say what from casing as OEM customers can have custom labeling or motor core can ne swapped.
Rad has done both. In the past casing swap (+sticker) and nowadays custom labeling.
KV can ne identified by no load speed (wheel of the ground full throttle) If you have the throttle.

I just received this same motor RMG06 48V750W(6) from Bolton for my radrover 5 and had noticed the one Electric bike world sells is RMG06 48V750W(7)
would there be a noticeable difference in torque between the two? On hills?

I would have preferred more torque for hills, but would rather not return the one I already have if the difference is minimal and not really noticeable.

(I also do have the 35amp controller on order)
Thanks.

I dont know the exact KV vs winding number relations but difference s between 6&7 is not big.
If you can test rear wheel of the ground full throttle speed with voltage information I can tell you the KV.

[springer03]

JTK77,
Thanks but I haven't  installed it yet, I just received it and I am still waiting for the controller/display upgrade kit(back ordered)
I was just wondering if it was worth exchanging for the (7)
I didn't know how much 1 strand difference would make relating to torque when climbing hills.
If it's a small difference I'm not going to worry about it.
Thanks for the offer though!

[Altema]

Yes. Multistrand winding enables more copper fill. That's why the G060.750 can have thinner coil strand but still faster kv (in this case).
In overall the efficiency increases little but this is mostly beneficial in terms of fewer watts wasted in overheating as copperlosses. The difference naturally increases with more power used and is further effected by the increased copper temperature (increase in R).
I had the 750+52v+35A setup few years back but now running vented G062.1000 at 60v 40A..and going soon to custom 45-50A sinewave and custom 60v 24Ah 150A BT battery.

Just to be clear, the windings on both motors is single strand solid core copper. The Rad kV cannot be determined because the internal limiter prevents the motor from reaching it's natural freewheel RPM.

What controller are you using for your new setup? I'm keeping my eye out for a sinewave controller instead of the cheap trapezoidal wave controller like I have now. It gets the job done and put 1600 watts through the stock Rad motor for 600 miles, but the noise and lack of efficiency still annoys me.