Overvolting Bafang BPM

While we're still toying with the idea (and by we I mean me) how does the the thought of a dual q100 setup at 36v and about 20A sound to you guys?

Yea, I'm fishing for opinions before I lay down the money, but hey, isn't that what this forum is kind of (almost) maybe about?

V.

EDIT

I should mean that to be about 12A per controller per motor.

Yea I know 12x2 is something, just entertain me for a bit, would y'all?
 
Done it. Got the tee-shirt.

I've tried all three versions in 2WD: 201 rpm, 328 rpm and 260 rpm (Q100H). 201 rpm is too slow at 36v. The 328 rpm ones with 15A controllers are great over 15mph, but tend to draw the maximum current all the time up to about 20 mph, so the controllers overheat if you're not careful. The 260 rpm Q100H are nicely in between, but 20mph is about the max. I'm thinking that two 260 rpm Q100Hs with 12S would be the sweet spot. Using two of these motors in a full-suspension bike is better than a larger single one because they allow the suspension to work much better.
 
Ok so I'm looking at towing a trailer (gross weight around 350-400 lbs including rider) and to do that i wonder if this combo would suffice.

48v 15ah high C-rate from BMS
BPM (16)
either a KU123 or S12S controller.

Mild hills but nothing to long or too stupid.

What do you guys think? Will that little hub be up to the task?
 
Could do, I love my gearmotors and have also run dual. The wiring gets pretty bulky though. Jamming a MXUS on the back would be a lot simpler.
 
fourbanger said:
Ok so I'm looking at towing a trailer (gross weight around 350-400 lbs including rider) and to do that i wonder if this combo would suffice.

48v 15ah high C-rate from BMS
BPM (16)
either a KU123 or S12S controller.

Mild hills but nothing to long or too stupid.

What do you guys think? Will that little hub be up to the task?
Click to expand...

I have a 36V "high C-rate" battery from BMS Battery. It is made with 10C cells, far better than the run-of-the-mill E-bike 1-2C battery offerings. The voltage curve is steeper than hobby LiPo but it has a BMS and is safer.

I also have a rear BPM motor and even though it's a (code 10) 300 RPM model it still has plenty of torque. A code 16 should be a stump-puller, albeit a tad on the slow side even on 48V.

I like the KU series controllers, they are simple, reliable and work sensored or sensorless. Since the only motor failures I have had have been hall sensors crapping out the ability to switch to sensorless mode can get you home in such an event. The S12S being sine wave will run the motor quieter plus you can get the cool display.

-R
 
The code 16 gives a little over 15 mph at 48v and it pulls like a locomotive. It should be perfect. The KU123 allows 30A from the battery. It works OK on the throttle, but the PAS function is useless. The S12S is around 25A. It's a lot smoother at all speeds, so will be a lot more pleasant when climbing. The PAS function is excellent. I would choose the latter.
 
The BPM with 12S lipo is "safe" until how many continuous amps? 30a? 35a maximum? Thanks.
 
It depends on which winding speed you have, how much load it has to carry and what speed you go. A 36v code 12 or higher with a 100kg rider can manage just about all normal riding circumstances at 30 amps provided that you use it sensibly.
 
d8veh said:
It depends on which winding speed you have, how much load it has to carry and what speed you go. A 36v code 12 or higher with a 100kg rider can manage just about all normal riding circumstances at 30 amps provided that you use it sensibly.
Click to expand...

BPM code 11 with 48v battery (vmax 45 km/h) with total ebike + me = 90 kgs :D
 
Code 11 is 285 rpm at 36v, so at 48v it will do about 30 mph. Personally, I'd stick to about 25 amps. You can go higher as long as you're sensible about how you use it and keep the speed fairly high. How much current you give a motor is more about how you use it than the motor itself.
 
Lurkin said:
Curious - how many kms would you expect to get out of one of these at 500w?
Click to expand...

My code 10 (300RPM) BPM in a 26" wheel gives a tad over 26 mph (42 km/h) on 12S LiPo (50V max). A code 11 would be about 5% slower. Power consumption varies greatly with speed, terrain and amount of pedaling. With my Townie/BPM (260 lb/ 118 kg) I have used anywhere from 13 to 30 Wh/mi over moderate terrain with high to no pedaling effort at average speeds varying from 18 to 24 mph (29-39 km/h). The code 10 is modeled in the ebikes.ca simulator. http://www.ebikes.ca/tools/simulator.html

-R
 
Lurkin said:
As in, how robust are they to start with? 2,000kms doesn't seem like very much to me.
Click to expand...

You can't eat your cake, and have it too.
Geared motors have nylon gears that can melt if overvolted or overamped.
If you really want robust then don't mess with geared motors get a direct drive motor.

My very first build was a Direct Drive in 2009, I put 6 years of hardcore service and still going strong with no sign of weakening.
4 years full time and now 2 years winter service only.
Every month i clocked in 1000km. So what is that 4yr x12000 = 48,000km + 2yr x 3000km = 54,000 km traveled and still going strong.

Picture taken around 2010
bike_winter.jpg
 
Lurkin said:
Lurkin said:
Curious - how many kms would you expect to get out of one of these at 500w?
Click to expand...

Lurkin said:
Apologies, I was meaning I would expect to get ~2,000kms without servicing or issues? 3,000kms?
Click to expand...
Click to expand...
Click to expand...

As in, how robust are they to start with? 2,000kms doesn't seem like very much to me.
Click to expand...
They'll last forever if you run them within their design parameters. I ran my 500w 36v one at 36v and 30 amps for 3000 miles with no problems.
 
Racer_X said:
Lurkin said:
As in, how robust are they to start with? 2,000kms doesn't seem like very much to me.
Click to expand...

You can't eat your cake, and have it too.
Geared motors have nylon gears that can melt if overvolted or overamped.
Click to expand...

That hasnt really been an appropriate answer for five years or more. It's almost impossible to kill off the war stories even in 2015.

I'm going to need to pay Kepler a beer every time I steal his video link:
https://www.youtube.com/watch?v=3EgShvl5KvY
 
What are you referring to by "they", the motor, the gears or the clutch?

http://www.greenbikekit.com/bafang-bldc-hub-motor-clutches.html
 
I keep a spare clutch in stock if ever needed. Just sold my last two motors. Should probably order another batch....
 
Can you PM me the price you usually charge? Further, can you also PM me about your Bluetooth controllers (if they are no longer for sale/ commercially sensitive I'll stop asking).
 
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