Plans: bbs02 + geared front hub motor

[skinkken]

Hello. I have been planning getting some more e-power to my bike. Winter is beginning here in finland and I don't plan riding in winter, so I have time to get some upgrades.

I currently have some 36v 250w rated geared front mxus motor. I bought it from a local ebike seller that had rebranded it. No load speed at 39.5V is about 31.7kph in 700c wheel. I saw a 250 rpm mini-might mentioned in some post in this forum.

I have a 36v 10ah rear rack lifepo4 battery, with some research I came to a conclusion that it has very low c rate. I'm going to try to sell it. My motor controller is 14A. It's quite small controller, I don't know it it can be used with a 48V battery (that I plan buying). That could be checked opening the controller but I'm not going to do it right now as the motor has some problems with odd sounds and I'm getting it to the shop checked.

So I plan getting a bbs02 750w, probably from greenbikekit.com. I also want to keep the front motor. With my very low weight I would be getting really good acceleration with 2wd as both are quite high torque motors. (48V*39A = 1872W, but very good torque and efficiency (2 motors, 2wd))

I'm planning to get a pre-built 48V 12ah headway battery (from GBK too), and put it into a bag to the bike triangle. Both motors would be using this battery.


Some things I have been wondering:
-I have a shimano nexus 7 gear hub, and with the crank freewheel I would also lose the back pedalling braking capability. It's the only rear brake on the bike. I would need to somehow install new rear brakes. Shimano roller brake? Is it possible to install V brakes somehow?

-48V 12ah headway battery. I was planning to get some triangle bag to fit it and the front motor controller there. I would want it to be water proof so if it rains I would be able to get leave it there for some time. I also want to be able to take the battery with me. An option would be also to make the battery waterproof instead of the bag. Would it be possible to somehow make the whole battery water proof? I don't see any problem covering whole thing with plastic bag or something like that.

-Wiring. I currently have this kind of water proof connectors. http://i00.i.aliimg.com/img/pb/274/367/576/576367274_452.jpg I need to make 1 throttle (currently owning a thumb throttle) run 2 motors. How can I wire the throttle to both systems? I'm confused about all the different connectors, what do I need?

-If it turns out my front motor controller can't do 48V, where could I get one that can? That 14A is probably enough, more would overheat it.

-steel frame and fork, 31.7 kph no load speed with 39.5V, 14A, no torque arm (only lock washers those came with the motor), no problems. The motor feels like having quite good torque. My LCD display shows about 480W peak at about 20 kph. 48V would't wreck it, I think?


I'm a student and not very rich, so I can't spend infinite money. My goal is a working and flexible system with about 50 kph cruising speed and stunning acceleration capability.

 

[mlt34]

A few things:

1) 39 amps? That front motor isn't going to last long at all with 39A. The BPM controller won't give you 39A without some serious modification, and at that point you'd risk destroying the thing.

2) The 48V12AH headway pack should be an awesome pack, but it would take a really big triangle bag to fit it. Triangle bags are really convenient (I love them and use them on many bikes) but their main problem is that fitting square packs means you need a really big triangle bag. You wind up with a lot of wasted space in the triangle corners and so the usable rectangle you can draw in the triangle is fairly limited. Just consider if that will work for you. I've seen a lot of batteries miss fitting into triangle bags by less than an inch.

3) You can install V brakes if your bike has the studs mounted on the frame. If not, you're out of luck on that front.

4) Cling wrap works surprisingly well. Also you can buy large diameter (you'll probably need 250 mm-ish) heat shrink on eBay by the meter. You'll have half a meter or so extra, but it's good to have some spare. It won't be 100% waterproof, but it will keep water drips from getting into the battery and instead direct it down the sides. A combination of the two might work well. Keep in mind that waterproofing also means air-proofing, and air cooling is your friend.

5) The throttle can receive power and ground from one controller but the signal wire needs to be shared by the two controllers.

6) 48V controllers can be had all over eBay, BMSbattery, etc. Most have current ratings in the 20-30A range which is fairly high for your geared front hub, but you could cut one of the shunt wires to drop the current by 33% to 50% depending if it's a two or three wire shunt.

7) On the fork issue, you're probably ok but then again do you really want to risk it? 250 watt hubs even overvalued to 48V (so something like 600W) are usually ok in steel forks. I've only spread open a steel fork with a BPM motor and that is a much higher torque motor. But then again, a good torque arm doesn't cost much, especially compared to how much that 48V headway pack will cost. If it was my bike, I'd install a torque arm on one side. This Grin torque arm would be perfect.

 

[motomech]

Hello. I have been planning getting some more e-power to my bike. Winter is beginning here in finland and I don't plan riding in winter, so I have time to get some upgrades.

I currently have some 36v 250w rated geared front mxus motor. I bought it from a local ebike seller that had rebranded it. No load speed at 39.5V is about 31.7kph in 700c wheel. I saw a 250 rpm mini-might mentioned in some post in this forum.

I have a 36v 10ah rear rack lifepo4 battery, with some research I came to a conclusion that it has very low c rate. I'm going to try to sell it. My motor controller is 14A. It's quite small controller, I don't know it it can be used with a 48V battery (that I plan buying). That could be checked opening the controller but I'm not going to do it right now as the motor has some problems with odd sounds and I'm getting it to the shop checked.

So I plan getting a bbs02 750w, probably from greenbikekit.com. I also want to keep the front motor. With my very low weight I would be getting really good acceleration with 2wd as both are quite high torque motors. (48V*39A = 1872W, but very good torque and efficiency (2 motors, 2wd))

I'm planning to get a pre-built 48V 12ah headway battery (from GBK too), and put it into a bag to the bike triangle. Both motors would be using this battery.


Some things I have been wondering:
-I have a shimano nexus 7 gear hub, and with the crank freewheel I would also lose the back pedalling braking capability. It's the only rear brake on the bike. I would need to somehow install new rear brakes. Shimano roller brake? Is it possible to install V brakes somehow?

-48V 12ah headway battery. I was planning to get some triangle bag to fit it and the front motor controller there. I would want it to be water proof so if it rains I would be able to get leave it there for some time. I also want to be able to take the battery with me. An option would be also to make the battery waterproof instead of the bag. Would it be possible to somehow make the whole battery water proof? I don't see any problem covering whole thing with plastic bag or something like that.

-Wiring. I currently have this kind of water proof connectors. http://i00.i.aliimg.com/img/pb/274/367/576/576367274_452.jpg I need to make 1 throttle (currently owning a thumb throttle) run 2 motors. How can I wire the throttle to both systems? I'm confused about all the different connectors, what do I need?

-If it turns out my front motor controller can't do 48V, where could I get one that can? That 14A is probably enough, more would overheat it.

-steel frame and fork, 31.7 kph no load speed with 39.5V, 14A, no torque arm (only lock washers those came with the motor), no problems. The motor feels like having quite good torque. My LCD display shows about 480W peak at about 20 kph. 48V would't wreck it, I think?


I'm a student and not very rich, so I can't spend infinite money. My goal is a working and flexible system with about 50 kph cruising speed and stunning acceleration capability.

That's a "Euro" kit powering the MXUS, which means it is very low power.
I have run as high as 1500 Watts on the Geared Mini-Might(MXUS), but now limit it to 1200 Watts(12S Lipo\25 A controller)because above that a frt. mount motor can get a little tricky to control in certain situations.
I am sure your controller will not survive at 48Volts. I like the Elifebike 500 Watt 9-FET controller because it is smooth, durable, inexpensive and has a very nice Low Voltage Cut at 41V, but actually use an Infineon(probably out of your budget)because I need to run my MXUS sensorless(the Halls are the weakness of the MXUS). But the Elifebike controller only matches the 810 display. If you have a LCD1 or LCD3 display and want to keep it, you might want to look at the S12S controller from BMS Battery.
Having said all that, I think your idea of going 2WD with a geared frt. and a mid-drive is not a good one.
For one thing, the MXUS in a 26" whl. at 48V only does 23 mph and to get it to go faster you would have to add lot's of extra Volts at which point, it becomes unreliable. For all the complication of using two dis-simular systems, it just wouldn't be worth the trouble. Besides, 2WD works better with two systems that are more or less the same.
I would suggest just going with the mid-drive kit you mentioned and use enough battery to reach you goals.
You could sell the frt. MXUS kit, but you will have a problem. You probably had to file the frt. fork drop-outs to fit the MXUS, so you will have to replace the forks to go back to the original wheel.
maybe your best solution would be to sell your ebike as it sits now and start over with another bike. If you did that, you would have the option of using a big rear hub motor, like the BPM.
To go 31 mph(50 Kmh), you will probably want to use a MTB with suspension anyway. Unless your roads are "baby-butt" smooth, that kind of speed on a ridgid bike is not safe.
If your budget does not support this, think about staying with just the MXUS at 48V/20A. That would be a nice Ebike that would be fast enough to be fun and that speed would be a much better match for your bike.
If you want to build a "hot rod", you need to start with a bike has Hyd. disc. brakes and at least frt. suspension.

 

[ddk]

afaik my muxus motors, rated at "350W" are he same as the "250W" motors. The difference would be the controller.
I use 23A controllers that have 63V capacitors and indeed, I use 14S LiCo batteries for52-56V operation.
My trikes, with two completely dissimilar motors are both capable of +50kph (31mph) but I've programmed the motor systems to go no faster than 32kph (20mph)
I'll note I rarely ride above 25kph.
My next trike, should I build it, will use a bbs02 and one of my front wheel muxus motors. Hence my interest in your build.

-I know nothing about headway batteries, but I'm to assume they can safely source 50-60A you'll require upon starting from a stop.
-I prefer separate throttles but I have wired two motors to one throttle, where both motors were the same type. They shared the same battery so they had a common ground.
-I don't live in Europe, but every bike I've seen has a provision for cantilever brakes.
(It's that flat bar welded across the rear fork arms with the hole drilled in it.)
Cantilever brakes work fine in the rear, as long as you have good front brakes.
I use cantilever brakes, both front and rear on one of my trikes. However, it's equipped with a DD front motor using regen braking which does most the 'stopping'.

edit- I have no idea what 'stunning acceleration' means.
but
Both my trikes can match the speed of most cars from a dead stop for a few meters