Bafang BPM2/KU123 or EBK on Bike-E

[bachmaninoff]

So instead of having the Bafang on a Trident Stowaway II, opted to put it on my Bike-E instead. Prior to this the Bike-E had an e-bikekit.com installed with 36V 15Ah Ping battery. Still using the Ping, but now with the KU123 and Bafang.


http://flic.kr/p/e44zPJ
http://flic.kr/p/e3XWhP

On the flats I was getting about 18.5mph - 19mph. A slight improvement over the e-bikekit 350W geared motor at 17.5mph. I connected the high-speed setting on the KU123, which raises the audio pitch of the motor only slightly (less than half-step if this were an instrument). I'm wondering if there's anything else I can do to squeeze one or two extra MPH out of this before I start looking at increasing voltage. I thought I saw a few posts where people were getting just over 20mph with the Bafang/KU123 using 36V. Is it because of my 20" wheel that I'm not quite there? Or maybe my tires...?

Just a quick test in the garage after I got back:

http://youtu.be/dPH5yFfMf4o

 

[motomech]

So instead of having the Bafang on a Trident Stowaway II, opted to put it on my Bike-E instead. Prior to this the Bike-E had an e-bikekit.com installed with 36V 15Ah Ping battery. Still using the Ping, but now with the KU123 and Bafang.


http://flic.kr/p/e44zPJ
http://flic.kr/p/e3XWhP

On the flats I was getting about 18.5mph - 19mph. A slight improvement over the e-bikekit 350W geared motor at 17.5mph. I connected the high-speed setting on the KU123, which raises the audio pitch of the motor only slightly (less than half-step if this were an instrument). I'm wondering if there's anything else I can do to squeeze one or two extra MPH out of this before I start looking at increasing voltage. I thought I saw a few posts where people were getting just over 20mph with the Bafang/KU123 using 36V. Is it because of my 20" wheel that I'm not quite there? Or maybe my tires...?

Just a quick test in the garage after I got back:

http://youtu.be/dPH5yFfMf4o

I thought I saw a few posts where people were getting just over 20mph with the Bafang/KU123 using 36V. Is it because of my 20" wheel that I'm not quite there? Or maybe my tires...?

Both, the overall circumference effects the gearing and the 20" set-up really kills the top speed. Going to a 24" wheel/tire would would add 2-2.5 mph and a 26" a solid 3 mph to top speed.
According to the Ebike CA Sim(using the BMP 36V as a sub for the BMP II), going to 48V would raise the top speed by 4 to 5 mph.

I'm wondering if there's anything else I can do to squeeze one or two extra MPH out of this before I start looking at increasing voltage.

Not really, "you can't fool Mother Nature(laws of physics)". You would need to go to a bigger wheel or increase the voltage or both.

 

[neptronix]

Give it more voltage.
A bafang BPM2 in a 20" wheel is awesome, but you will need to add volts to get the speed back.
The bonus, is that you get more torque than you would if you ran it in a 26" wheel. Probably a lot more.

 

[d8veh]

My calculation says 18.5mph with the three-speed switch disconnected. The only way after that to get more speed is to use the three speed switch in its high position (or join the wires), or use higher voltage - or chuck it off a cliff. Alternatively, you could get a code 8 motor if you can find one.

 

[StudEbiker]

That will be a nice little Bike E when you get everything tidied up. I wish I could have found an AT for at least one of the two I have done. I bet it makes for a much more pleasant ride.

Have you joined the Facebook group? Lots of good Bike E info over there.

Also, I just put a MAC of unknown wind on my GFs Bike E and am getting a top speed of 20.5 on 36v LiFePo4. It's a great zippy little ride with incredible torque.

Enjoy the ride!

 

[motomech]

If your GF's bike has 26" wheels, that would be a 10T wind, about the same as a BMC V2T.

 

[bachmaninoff]

Have you joined the Facebook group? Lots of good Bike E info over there.

Yes I used to be a member, but I disabled my Facebook account. Quite a time sink! Better time spent reading these forums and learning!

I hear the LiPo calling me...

 

[bachmaninoff]

Give it more voltage.
A bafang BPM2 in a 20" wheel is awesome, but you will need to add volts to get the speed back.
The bonus, is that you get more torque than you would if you ran it in a 26" wheel. Probably a lot more.

Yeah that makes sense. Thinking about either getting a booster pack from Ping or starting LiPo.

 

[StudEbiker]

If your GF's bike has 26" wheels, that would be a 10T wind, about the same as a BMC V2T.

No, it's a Bike E so it is a 20" wheel.

 

[bachmaninoff]

I've recently been riding my BikeE with an e-bikekit system (circa 2011), but with the BPM2 instead of the EBK geared motor. Seems to be plug and play! Used this configuration 6 times, so it's got 240 miles on it so far. I had to put Loctite on the spoke threads since they kept coming loose (BMS Battery ones, not e-bikekit ones). Eventually I'll replace it with the KU123 stuff after I sort out the rat's nest of wires exploding from it. Actually I have a spare e-bikekit controller that bit the dust during another bike accident, so I could use the cables from that one and solder them onto the KU123... The KU seems to put out a slightly higher output than the EBK controller.