Bafang BPM Marin Build

[Haste]

So finally...my real first "build". I bought a 9C DD hub before, but I figured I needed the freewheel and the startoff torque of a geared hub. I have an extensive background of mopeds, motorcycles, and even a motorized bicycle build
My motorcycle I never rode more than 10 miles, the mopeds constantly broke down and got pulled over, and the motorized bicycle just cracked the frame in 2 weeks.Im happy to say I believe ive found a new growing hobby that I will love, and stay behind the radar riding.

-1997 Marin Hill Hawk, vbrakes and RST front suspension fork
-Bafang BPM 2 code 8(high speed,any idea how to break these open?)
-BMS Battery KU123 500W 12Mosfets controller
-and at last, the battery in which I need to find out what im going to use.

I really just need a plug and play battery, such as a 48v 15ah lifepo4. The controller says max amps 30a, so I believe a 15ah lifepo4 pack should be fine? Im aiming for 32mph top speed, 35+ downhill.

Once I finish my house in 5 months I may go 15s lipo, but not for now as Im rather forget full. Any idea on a 48v lifepo4 vs 15s lipo as far as speed? Im thinking 15s may net only a little more top end?

[motomech]

I'm curious.
It would appear that the BPM came from BMS Battery[it's a code 8]. Why didn't you get a battery from them?
There would not have been any additional shipping costs?

[miuan]

There are always additional shipping costs, although they are smaller than the initial shipping.
For this kind of build, I'd recommend their Headway packs with high current BMS.

[Haste]

hello! no responses..i guess due to no pictures yet! ha ha

Receiving a basic 48v 20ah lifepo4 pack for starters. Should do fine until I go a123 or lipo...and of course go to a DD hub. I just want a reliable commuter for now.

[Herrsprocket]

Just curious, the BPM 2 has several listed dropout widths available, the least being a 138mm size. Was your bike's rear dropout width a little larger than the normal 135mm's? Or did you find that you could spread your rear stays to accommodate the BPM? Or did you find that the dropouts width on the motor was not really larger than 135? Just wondering.

[pchen92]

Hi,

I don't advice you to run the code 8 on 15s lipo. This motor is a really fast winding (55km/h on the flat at 48V) and the controller won't appreciate the 7V more.
I have this motor on 48V on my full suspended MB. It's fast enough and if you don't pedal, the controller will shut down in 10 minutes at 55,5V (25°C). I tested it.
You need to pedal to help the motor because at top speed it doesn't have enough torque to climb a small hill.
To give you an idea, here is what I can do with my bike : http://www.youtube.com/watch?v=EL4vw6Ni ... ure=colike

[Haste]

pchen92, i love you.

i have been looking for awhile for a nice video of someone actually running the 8t bafang bpm. Im assuming yours was the bms battery 48v500w 393 rpm hub? I will be running a 48v20ah battery also.

I had no idea it could get up to a whole 55km...thats quick for a 130 dollar motor! Only issue is its pretty hilly around here, but feather the throttle and pedal and I should be good? The downhills will be fun though! hello 60+kmph!!

[pchen92]

I think I ordered a 36V 500W at 393rpm. Don't exactly remember...
In fact, it depends on how long are your hills. If you have a 2km long hill and 4-5% I suggest you to stay at 35-40km/h and pedal to be safe.

I've just came back from a short run on a muddy and grassy path. Really fun, I have to pedal a lot but I can go 30km/h and it's very pleasant !
I'll upload a video tomorrow if the weather is fine.

[Haste]

thanks!! It seems you have great range also! 30 miles! Even when your going 50km/h you dont realize how fast it really is. You catch all the same lights as cars, ect.

[pchen92]

Well, in town I can't really exceed 45km/h and according to my measurements, my range is more like 70km.
Here is a video of the code 8 in forest http://www.youtube.com/watch?v=hoC7sdvi ... ideo_title

[Scottyf]

I've ran my bpm @ 66v nominal. But it's a code 12. This was in. 700c wheel.
I don't use a speedo but know roughly my cadence is along the lines for 35mph+ but my gears are only 48 front 14 rear so my legs spin out before it reaches that speed.

It scary so only run it at 44v for commuting. It's probably similar at 66v as the 8 turn but without bogging down. It will wheelie in when I'm in my highest gear without much effort. But that's running it at 30amp.

But that video looks similar to how Mine runs at the higher voltage. Either way it's a bit to quick on thin road tires.


Good luck with the build though! The bpm is a pretty strong motor for a geared variant. Mines took a year of abuse so far and I've never even come close to cooking it. I've dumped 2.3kw into it without much of a problem.

[motomech]

Well, in town I can't really exceed 45km/h and according to my measurements, my range is more like 70km.
Here is a video of the code 8 in forest http://www.youtube.com/watch?v=hoC7sdvi ... ideo_title

What a camera!!!
Great vid, it could be a TV commerical.
Thanx