Announcement

Collapse
No announcement yet.

Bafang 750W 135mm front for fatbike

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • tonyb
    replied
    Anyone know where I could buy one of these motors for the front 135mm dropout. The lunacycle link is dead. I've searched and looks like no one sells the front version of this motor.
    Possible part number for this could be F MG060.750.D
    Last edited by tonyb; 06-30-2020, 01:30 PM.

    Leave a comment:


  • wardo
    replied
    I really love this set up, but can't find that front hub drive anyplace. Any ideas? Do you have the part # per chance?
    Thanks,
    Ward

    Leave a comment:


  • prof.power
    replied
    Originally posted by MoneyPit View Post
    I can confirm that a single 52v (58.8v peak) 25R battery with a BMS of 50a continuous, 70a peak, can power two of those same motors where each has their own controller that peaks at 35a with a 17a continuous rating. i.e. more powerful than yours.

    The above configuration yields a peak speed of roughly 50 km/h. A bit less than when I run two batteries to power the two motors.
    Now I use a battery on the LG MH1:
    - rating 48V;
    - maximum 54V 35A;
    - capacity 15,6 Ah;
    - weight 3.2 kg.

    I feed 16A to the motor. It feels very powerful. Very fast start and set speed up to 50 km / h.
    I think that the battery at 72V on the Samsung 30Q will be more than enough. And it will be enough to feed 25A per motor.
    But the mileage is not enough. I drove relatively little on the current configuration, but at the maximum speed you can drive at least 25 km. It suits me to ride to work and back.
    I'm afraid to imagine how powerful the 35A configuration is on the motor. But I can not find out yet. Controllers will not allow.

    Soon I will make the light: front light, front and rear indicators, brake light and beep. Cruise control and power button on the controllers are already there. Everything will be displayed on the steering wheel straight to the motorcycle buttons. Very convenient solution.
    A friend will make a wattmeter and then it will be an ideal electric bike for quick movement around the city.

    Leave a comment:


  • MoneyPit
    replied
    I can confirm that a single 52v (58.8v peak) 25R battery with a BMS of 50a continuous, 70a peak, can power two of those same motors where each has their own controller that peaks at 35a with a 17a continuous rating. i.e. more powerful than yours.

    The above configuration yields a peak speed of roughly 50 km/h. A bit less than when I run two batteries to power the two motors.

    I only ran that bike with the single battery for a limited time. The battery was a good size of 17.5ah. Running two motors on it worked fine... but range was compromised of course. If you are planning on running only a 15ah battery you can expect to a) have short range and b) not expect that battery to last a long time since you will no doubt be charging to full capacity and have a deep depth of discharge every time. Pretty much beating the hell out of it.

    My new AWD bike with a BBSHD in the back and an economy tune on it is eating about one volt every 3.1 miles. I have a 52v, 25R 20ah battery that loses about 5 volts for each leg of my 2-leg commute. On an 80% charge I can make the round trip of 31 miles and be at around 45 volts... 18% left which is skating on thin ice. I charge at work though so I'm fine.

    Leave a comment:


  • prof.power
    replied
    Originally posted by MoneyPit View Post
    - Samsung 30Q's are a new-ish battery that gives you some of both capacity and high output. They are not ideal on either end of the scale.
    I like Samsung 25R cells and battery management systems with high output limits. My 17.5ah Luna Storm that powers my rear Bafang 750 has a 50/70 BMS. My front motor is powered by two 30Q mini cubes parallel'd together to make a 12ah battery with a 60/100 BMS (do not try and use that many amps or you will kill the battery). My next bike will have a 20ah 25R with a custom 60/90 BMS and run both motors. I want to try and use just one battery for charging convenience. For long trips I can run the front motor with a 14ah triangle that has GA's and a 30/60 BMS which will run fine with my 35/17a controller.
    I'm going to do a battery on the Samsung 30Q elements. Configuration 20s5p:
    - rating 72V 50A;
    - maximum 84V 75A;
    - capacity 15 Ah;
    - weight 4.9 kg.

    Controllers: two 6FET at 25A maximum.

    Motor wheels front and rear Bafang:
    - 750W;
    - measured 394-401 rpm without load on 53.9V;
    - that is, 7.43 turns per volt;
    - according to the marking of the motors, they have 7 poles, so this is not a traction motor but a high-speed motor. This is confirmed by measurements.

    With this configuration, the design speed will be as follows:
    - at 84V, the speed is 83.5 km / h;
    - at 72V, the speed is 71.6 km / h;
    - at 50V the speed is 49.7 km / h.
    The question arises: can a current of 25A per motor (50A for both motors) provide similar speeds? The target speed is in the range of 50 to 70 km / h.
    Last edited by prof.power; 02-03-2018, 12:18 PM.

    Leave a comment:


  • MoneyPit
    replied
    You need to just research batteries in general and understand the capabilities of different 18650 cells. Understanding what makes up a battery - the cells and the BMS - tells you everything about the battery you are trying to buy and the battery you should buy for your needs.

    This is a good place to start: http://www.electricbike.com/category/technical/

    Quick notes:
    • You either get high capacity for lots of amp hours in your cells, or you get high amp output. Generally you can't get both at the same time.
      - Panasonic GA's are a common go-to for high capacity storage
      - Samsung 25R's are the king of high amp output and excel for motors like a Cyclone
      - Samsung 30Q's are a new-ish battery that gives you some of both capacity and high output. They are not ideal on either end of the scale.
    • When you pick a battery, pay attention to the BMS. What is its continuous capacity and peak capacity? Match that to your controller's continuous and peak capacities. It is good to have the BMS exceed the controller's maximums. It is bad to do it the other way around.
    I like Samsung 25R cells and battery management systems with high output limits. My 17.5ah Luna Storm that powers my rear Bafang 750 has a 50/70 BMS. My front motor is powered by two 30Q mini cubes parallel'd together to make a 12ah battery with a 60/100 BMS (do not try and use that many amps or you will kill the battery). My next bike will have a 20ah 25R with a custom 60/90 BMS and run both motors. I want to try and use just one battery for charging convenience. For long trips I can run the front motor with a 14ah triangle that has GA's and a 30/60 BMS which will run fine with my 35/17a controller.

    Leave a comment:


  • prof.power
    replied
    Originally posted by MoneyPit View Post
    52v nominal (58.8 peak). 35a peak. About 2200w per motor on a full charge so on the once-per-month balance charge or long-distance trip days, I am running 4400 watts, and I do peg the throttles as we have bike lanes on 50 mph superarterials here where I have no issues cruising on PAS at about 54 kmh. With a smaller person and no loaded panniers I'd be faster. The front wheel will spin if you don't apply the throttle carefully. It will still lose a bit of traction at the highest PAS level.

    Since this pic was taken I have mounted that same rack on the front. 60T chainwheel lets me pedal up to that 54kmh speed.
    I had a question about choosing the right battery. What kind of battery do you use? Please tell us about its characteristics: what type of batteries, maximum and nominal currents, voltages, as well as capacity and total weight. And most importantly - how much distance on it you can travel on it in different modes (for example at 20 km / h, at maximum speed, with and without pedals).

    Leave a comment:


  • MoneyPit
    replied
    I use inner tubes. They have Presta valves. Also known as French valves. You see them mostly on road bikes and higher end mountain bikes. Presta valves are locked down onto the rim and cannot move.



    That screw holding them down also means if you have really low pressure the valve doesn't fall into the tube when you press an air chuck onto it.

    Typically, tubeless setups use Prestas also.

    Leave a comment:


  • prof.power
    replied
    Yes, there are difficulties in translation. The terms are especially difficult to translate. So I try to write simple sentences. They are easy to translate and understand.

    5 or 6.5 mm thickness of torque arms? A lot of thickness. It seems to me that this will be enough even for powerful direct drives. Unfortunately, I have already ordered the ones whose images I applied. I'll try to travel with them.

    Under the word "camera" I meant "inner tube". I still do not understand. Do you use internal tubes? Or your wheels are tubeless?

    Leave a comment:


  • MoneyPit
    replied
    Yes those are double-wall Weinmann DHL80's, but branded as Origin8 DAT-Pro-80's. Same rim no matter which one you buy. You will only see cutout rims (perforations) on single-wall rims. The double wall rims weigh more but I value strength over weight reduction on an ebike that gets a daily beating.

    I think your translator is mistaking the word 'camera' for something else. Your text doesn't make any sense as-is. But I *think* you are referring to the inner tube? The valve stem? Regardless, nothing rotates within the tire. Double-wall rims have been around a lot longer than perforated ones with zero issues.

    For sure, the valve stems do not rotate at all because they are Presta valves and you screw a presta valve down to the rim on installation. It can't move and never does.

    In my opinion, a single-wall rim with cutouts is only optimal if you can benefit from it. If you are riding a fat bike like it was originally intended - slow, with human power only, across unimproved terrain (or a trail) then the weight reduction you get from the cutouts and the single wall construction makes sense. If you are riding a fast ebike on the streets then I think they make no sense at all when stacked up against a double-wall rim that is inherently stronger and you have a motor that wipes out the weight disadvantage.

    'dropout amplifiers' translate to 'torque arms' in English :-) My drive-side torque arm is a mishmash of different parts. I decided I had the extra parts so what the heck lets use them to really lock this thing down. Its definitely overkill, especially considering I have a second torque arm on the other side.

    I have destroyed a steel fork (spread the dropouts) with one of these motors when I had no cutouts and went to 100% throttle from a stop. If I were you I would (a) use two torque arms and (b) use a better torque arm. 3mm thickness is not much. It won't bend but you want more meat gripping on your axle. With that said, I have a couple of these and they are very well made, that seller is in your country and he's a straight-up guy. He sells the same design you show above albeit in 4mm thickness. I very much recommend you go with the thicker design he sells, and then maybe use the link below and use that one for the non-drive side to attach to the brake mount (assuming you have IS mounts on your fork and not posts).



    I have tried to use that design and the thicker Grin Technology original version and could not make it fit. the angle of the axle flats was wrong.
    I prefer these 5mm arms and have two to use on my current project:



    If you want to REALLY get serious, Grin Technologies originated these designs and their original versions are here. Thicknesses are 6.3mm.

    We now have a full range of 7 torque arm models in production that together fit almost all front/rear 12 and 14mm axle motors, along with special ones for regen braking use. We also offer motor-specific arms for the Grin All-Axle and GMAC motors.


    I prefer the ST version of the Thudbuster. If you are riding offroad perhaps you need the extra travel. Personal preference I think. On impressions: You don't know its there. Your angle to the pedals doesn't change enough to notice. What I did notice was my back pain immediately and permanently went away the day I installed it, so I have put them on by other RWD single-motor fat cargo bike and this new 2WD bike gets one as well.

    Leave a comment:


  • prof.power
    replied
    Originally posted by MoneyPit View Post
    The angle is not optimal, but it is not bad, either. Thats why you use 16mm nipples made of brass, to help counteract that issue. You are correct that if you try to use 12G you will have to drill out the rim as the nipples will be larger than the holes. Another possible option is Sapim polyax nipples.

    I was concerned too but my wheelbuilder assured me the DTs with long brass nipples were plenty strong as was the double wall rim. Its hard to argue when there has been no loss of perfect true after more than 4800km from March to December.

    52v nominal (58.8 peak). 35a peak. About 2200w per motor on a full charge so on the once-per-month balance charge or long-distance trip days, I am running 4400 watts, and I do peg the throttles as we have bike lanes on 50 mph superarterials here where I have no issues cruising on PAS at about 54 kmh. With a smaller person and no loaded panniers I'd be faster. The front wheel will spin if you don't apply the throttle carefully. It will still lose a bit of traction at the highest PAS level.

    Since this pic was taken I have mounted that same rack on the front. 60T chainwheel lets me pedal up to that 54kmh speed.

    Do you use a double rim on your bike? Are your wheels with tubers or tubeless?
    As far as I know, there are no perforations in the double rims and the camera can rotate in the tire. And the weaker the pressure, the more the camera turns.
    I'm going to use a single-walled rim with perforations to avoid turning the cameras at low pressures.
    Such a design is optimal, do you think?
    Of course, if you use tubeless technology, you do not have such problems and you can use a double-walled rim.
    And of course, I liked the design of the dropout amplifiers on the front fork.
    I'm still going to use a simpler design (plate thickness 3 mm):
    Click image for larger version

Name:	full_Perednui.JPG
Views:	2325
Size:	30.8 KB
ID:	55642
    Hmm, I see you're using Cane Creek Thudbuster ST Seatpost. I also thought about it, but thought about the version of LT (75 mm stroke). Do you like this solution? Can you describe your impressions of this transition? When I bought a fatbike, I liked that the low pressure of its tires can eat the smallest irregularities. While on narrow tires (up to 2.5 ") and high pressure (from 2 bar) such small irregularities are very strongly felt, even on full suspension, but the average and large irregularities are still felt on the fetbike and still have to stand up, especially on the narrow 27.2 mm seat post.

    Leave a comment:


  • MoneyPit
    replied
    The angle is not optimal, but it is not bad, either. Thats why you use 16mm nipples made of brass, to help counteract that issue. You are correct that if you try to use 12G you will have to drill out the rim as the nipples will be larger than the holes. Another possible option is Sapim polyax nipples.

    I was concerned too but my wheelbuilder assured me the DTs with long brass nipples were plenty strong as was the double wall rim. Its hard to argue when there has been no loss of perfect true after more than 4800km from March to December.

    52v nominal (58.8 peak). 35a peak. About 2200w per motor on a full charge so on the once-per-month balance charge or long-distance trip days, I am running 4400 watts, and I do peg the throttles as we have bike lanes on 50 mph superarterials here where I have no issues cruising on PAS at about 54 kmh. With a smaller person and no loaded panniers I'd be faster. The front wheel will spin if you don't apply the throttle carefully. It will still lose a bit of traction at the highest PAS level.

    Since this pic was taken I have mounted that same rack on the front. 60T chainwheel lets me pedal up to that 54kmh speed.

    Last edited by MoneyPit; 01-12-2018, 03:45 PM.

    Leave a comment:


  • prof.power
    replied
    Originally posted by MoneyPit View Post
    prof.power I just realized those pics above give you an excellent look at how the DT Champion 2.0's seat in the hub.
    Is the angle of the needle in the rim optimal? Looking at your spokes, you can say that it is good, but I suspect that the spokes sit in the holes of the motor not as they should. Still, I think I'll use at least 13G spokes. Maybe even 12G, but for this it will be necessary to reamer the holes in the rim.
    I plan to use a battery with a rated voltage of 72V and a nominal and maximum current of 25A. The controller is planned for 6Fet 25A. Voltage engine will digest without problems, but about the current is not yet clear.
    What are the voltages and currents you use on the front and rear motors of this bicycle?

    Leave a comment:


  • MoneyPit
    replied
    prof.power I just realized those pics above give you an excellent look at how the DT Champion 2.0's seat in the hub.

    Leave a comment:


  • MoneyPit
    replied
    Cutting the dropouts can result in loss of integrity of the dropout if there isn't enough meat on them. On my first bike, on my first set of forks I squared off the round of the top of the dropout and this allowed the thing to seat just a bit higher - the inward curve of the top of the dropout left a bit of usable dead space that squaring them off allowed to be used. This was enough to seat the 12mm axle fully in the dropout.

    After a while I replaced that fork with a stronger one and on those dropouts, rather than squaring it I just used a rotary tool to take the paint down to bare metal. Here again there was just a bit of dead space and utilizing that gave me a good connection. On that bike, whose axle is pictured both sides below, I installed two torque arms plus I upgraded all of the nuts and hardware - did not use the Bafang shouldered nuts with serrated bottoms, and instead used a large flat washer with a serrated ring washer underneath the Grade 8 M12 replacement nut. Using a normal nut gained me back some threads, as did the use of the serrated ring washer. Since I added some very fat torque arms, net result was flush, full thread engagement.

    The two images below are links to much larger versions. Open them up in a new window if you want the gigantic version, where you can get a close look at the seating.





    These ring washers are outstanding for locking together a nut and washer subject to vibration. And they take up almost nothing in terms of threads. Invisible as they are smaller than the nut. the one in this picture is about twice as thick as those found in local hardware stores.

    For my most recent build, I am doing things very differently, and I may not be done. First, that fork - an Origin8 Scout fork - is aluminum. Livable as this motor is not powerful enough to break it. But still bears scrutiny. That fork does have deep indentations to seat the axle nuts and I am using ring washers again, in two different sizes, to overcome this under the nut... this time as seats to raise the contact point of the nut. Two layers with one larger than the M12 and fitting perfectly and filling the depression, and the second being an M12. There is enough meat around the dropouts that I still have full contact. Coupled to two torque arms again, I should be be fine.

    However I have a 150mm Chromoly Motobecane Lurch fork on the way that I am going to play with and see if I can make it work. I am thinking the two torque arms, which are 7mm in depth each, give me 14 of the 15mm of extrra spacing those 150mm forks introduce. I am going to try and put them inside the fork blades rather than outside, then bolt them up as needed. I have a number of different torque arm parts on hand so - like the right arm you see above, where I decided to use a second anchoring point for the sake of overkill - I may need to get a little creative to make it work. But thats part of the fun of the project.
    Last edited by MoneyPit; 01-12-2018, 12:52 PM.

    Leave a comment:

Working...
X