Bafang or Cute? and freewheel question

[easyrider]

hi all from Australia, sorry for ignorance but I have done some reading and can't seem to work out what the story is with rear freewheel (sprocket). I have no desire to run gearing so was wondering is it possible to remove the gearing cluster and fit a single freewheel? Wouldn't doing so limit the need for dishing the wheel?

This is my plan so far, if anyone cares to critique it and/or make suggestions I would be very much obliged:
- 10Ah 48V ping Lifepo4 pack mounted in frame on a road bike with 700c wheels, rim brakes (i.e. no discs). (FROM PING CHINA)
- Bafang QSWXH rear wheel hub motor (3kg) OR Cute 07C OR Cute 100SX (from what I can gather these all fit in 135mm dropouts, definitely a limiting factor with the cute motors...) (BMS BATTERY CHINA...they seem the cheapest..is this for a reason?)
- Cycle analyst limiting current to 10A (1C for 10Ah)
- Sensored/Sensorless...no idea, depend on suitability with motors (Not sure where to purchase controller, need to choose motor first)
- I will be happy with anything more than 30km range on relatively flat ground pedalling a majority of the time.

As you can probably tell my light weight e-bike will be built on a budget and suited to city commuting and is not built for high power or speed (above-mentioned motors all rated ~200-300W), all I want is a little assistance on hills. (My inspiration is the swiss? swedish? sorry guy i cant remember on this forum who turned out a very clean cannondale badboy with beautiful fibreglass frame mounted battery box..if you haven't seen it check it out) I just have a couple of questions that are stopping me from getting out the cheque book:
-I figure I'll be making roughly peak 500W with no load at 48V and 10A. Will all these motors tolerate the increased voltage as well as each other?
-Am I stuck with running a 6 pr 7 speed freewheel? Im assuming the gears cant be removed and the motor shifted along the axle to allow less dishing?
-Should I run sensored or sensorless? I understand the basic pros and cons of both, and having no experience it appears running hall sensors is just easier as more controllers are compatible. So of course I want to do sensorless...because its more difficult..but I really dont care either way, limiting complexity (breakdowns) is my goal. I just need specific info relating to the motors Im looking at.
- is it possible to limit the output current of the controller? Obviously it is...but is it difficult? Can you rely on the electronic current limiting function of the cycle analyst not to fail and ruin my system?
- Can anyone suggest alternative motors/equipment that may suit my needs.

Sorry for the questions but I have never seen a hub motor in the flesh (or steel) so its difficult to know exactly if and how they can be modified. Gathering all the information required is certainly tedious after a while especially since its scattered all over the internet. Whenever I start researching ebikes I always end up with about 20 different tabs open in my browser, all containing different little bits of info or specs. but I enjoy seeing other peoples creations. I would very much appreciate any help you can provide. cheers

 

[jbond]

The rear motors have a completely standard freewheel mount. So there should be no problem with replacing the typical 7 speed Shimano freewheel with a BMX single free wheel. There are reports on ES of people running 40v-20A with the Bafang motor. If you know you only want 10A then get an Infineon/Keywin style controller from Lyen or ECrazyman (and others) Get the programming interface and set the battery current to whatever you need. Or set the controller to a higher current and use a CA to reduce it, perhaps on a switch.

Just keep researching. There's a lot of information out there and you're not doing anything people haven't done before.

 

[dogman dan]

Or simply tell Lyen what amp limit you want. I think you are ok though, to use a 15 amp controller with the pingbattery. They won't draw 1.5 c 100% of the time at all, and will tend to cruise at ten amps on flat ground anyway.

I'm not so sure about 48v in those motors, but I do know the way I tend to ride I'd fry one. But if you pedal more and use the motor less continuously, you can get away with the 48v I think. I just have a run it till she blows attitude.

Yes, you can put a single speed freewheel on it, but you will be stuck with the stock axle spacing most likely, and have to live with the dishing.

 

[easyrider]

thanks for the fast replies guys, you've just saved me hours of internet scouring!The Bafang sounds like its been more thoroughly tested and the extra 1kg over the 100sx should make negligible difference to handling. I appreciate the time taken to help out a new guy. cheers

 

[jag]

Your title question "Bafang or Cute" is a good one, and I think it is not authoritatively answered on ES. By contrast in the heavier hub motor classes (BMC/MAC, 9C, Clyte), there is both 3rd party technical data and true comparative user tests posted.

For the "Bafang or Cute", one has to still speculate a lot.
The smallest 250W Ananda/Cute (BMS battery name: "Cute") is just 2kg (lists at 1.6 at BMS battery, but others weigh it at 2kg).
The comparable Bafang/GM/cell_man 250W is 3kg. 50% heavier!
A really lightweight hub motor could be the ticket to convincing the significant other or friends to get into Ebiking.

The big difference between the two is that the small 108mm Ananda have 9:1 gearing, while the Bafang-like hubs have about 4:1 ratios. The higher ratio allows for a smaller and lighter motor making the same power. The Anada gets its higher ratio by having two stacked wheels in the planetary gearbox. The sun gear drives the higher tooth count gear iin the picture below, while the lower tooth count gear drives the ring gear, thus fitting a high ratio into a small space, yet with a reasonably large sun gear.

So how do they compare? Unfortunately evidence on ES is largely anecdotal. I spent some hours a week ago reading through the posts, and one can find that the Ananda/Cute, while significantly lighter also has some potential drawbacks: higher rolling resistance when pedaling, higher noise (maybe not a big deal at 250W anyway -- hubbies tend to get noisy only when over-volted/powered.)

So there may be a niche where the lighter Ananda/Cute makes sense. (E.g. Light bike for a small person or kid, or anyone who wants the lightest)

And there are other cases where the more common Bafang and similar hubs makes more sense.

Until direct people have made direct comparisons between the two, one has to still largely guess though.

B.t.w. if you haven't seen it already, ES vendor cell_man has a geared hub kit that may be of interest to you:
http://endless-sphere.com/forums/viewtopic.php?f=31&t=19971&start=0#p291754

 

[easyrider]

Jag I must say I when I started researching (mostly on this forum) I was a bit surprised at the lack of information/data (and perhaps enthusiasm) for lower powered, lighter bikes. Everyone has their own ideas I suppose and some of the high powered machines are pretty impressive but I definitely see a lower powered bike being of much more use for my purposes.

Thank you very much for your photo and info, you have filled in a lot of gaps for me and I'm slowly building a specs list for these smaller motors.
I was partially aware of the different stacked gearing setup in the 'cute' but I was interested to see the gears look to be straight cut as opposed to helical, as I think is the case in some other cute motors (perhaps the 128sx ?). I had also read reports of the cute being noisier as compared to the bafang which i'm not particularly concerned about. I wasn't aware of the gear ratios though so that is very good to know. I am not an engineer (in case that wasn't obvious already...) and this may be a silly question but, if the planetary gears in the bafang are 4:1, the wheel is turning 1/4 turn (90 degrees) for every one turn of the gear, does that mean there is half the wear on the gears as compared to the cute at almost double the ratio? Or is there less load applied to the gears in the cute because they are smaller diameter or something? This higher ratio must have some limiting effect on max RPM and hence top speed? All these assumptions may all be complete garbage, its been a while since I read a physics text book...

I'm starting to think the cute might not be worth the effort since it only represents a weight saving of approx 1kg, which once considering the weight of the 10ah pack (I think 4.9kg), might not make a noticeable difference. Having said that, the light weight and small size still really appeals to me so I might have to just buy both motors and when/if the cute dies, replace it with the bafang.

On a side note I contacted Lyen re a suitable controller and he recommended a sensored version he makes. He helped another thing click for me too, sensorless is the best option for geared motors because the slower rotational speed (angular velocity? physics nazis please be kind ... ) causes reduced back EMF which causes the controller to malfunction. Aside from that he seems like an excellent bloke and was very helpful indeed. I'll be ordering the 6x4110 mini monster programmable edition (on Lyen's recommendation), a throttle and a cycle analyst.
Thanks for the link to cell_man also, he looks like another reputable seller, I haven't really looked to closely into where I'm actually going to buy the motor from so I will check out his wares and see what I can find.

I must say I'm amazed at the enthusiastic advice everyone's given me and very much appreciate the help. The ebike project is looking much less daunting already

 

[jag]

I agree that good information on low weight and low power options is scarce. There is a range of eBike possibilities from low weight low power hub motors to high weight and power hub motor, and as a different category are more DIY solutions such as friction drives and RC belt/chain drives. The medium weight hubbies are by far the most well known.

1. Friction drive. Adrian_SM and Kepler have threads on drives that weigh only about 1kg. In these the tire is driven directly by the surface of an outrunner motor. Therefore no weight added for transmission, but won't work well on tires with aggressive thread patterns. Should be perfect for a fair weather rider who needs occasional assistance (uphill). While Kepler sells part and Adrian may soon too, these are more DYI than swapping one wheel for a hub kit. Typically powered by lightweight 6s1p or 6s2p lipo and a light RC controller. This doesn't give a lot of range in continuous use, but as said is perfect for a power push uphill. (The RC motor can potentially output kWs while the battery lasts. Efficiency of a friction drive is unknown, but likely a bit less than using a gear or chain transmission). Total system weight as low as 2-3kg.

2. Light hub like the 250W, 2kg Ananda + 2kg of high energy battery. This would be good for a lightweight person riding with continuous assist in a pretty flat area. The low motor power means that battery chemistries with lower discharge rates but higher energy densities could be used for long range at minimal weight. (E.g. 30-40km range on the 2 kg of battery assuming LiCo with 150-200Wh/kg and "pedal assist" ebiking at 8-10Wh/km at 20-30km/h.). Total system weight about 4kg.

3. Medium hub like the 3-3.5kg Bafang and lookalike styles + regular LiFePO4 eBike batteries (about 100Wh/kg). Many opt for medium discharge rate pouch (e.g. Ping battery) or cylidrical cells and the smallest 36V 10Ah Ping weighs about 4kg. This is a well proven solution, and would likely be the least expensive per km in use. Total system weight around 7-8kg.

4. High power geared hubs (BMC/Mac/eZee 4kg) or DD (9C and lookalikes 6-7kg) + 7 to 10kg of batteries. These motors can tolerate 1.5-2kW power, and need a higher current battery to cope. For the popular Ping's this means the 7.5kg 15Ah 48V or 10kg 20Ah 48V, although lower weight batteries can be built (ate the expense of range; at the speed of these motors,30-50km/h, one needs 15-30Wh/km) with A123 (cell_man does this) or DIYer use LiPo, special chargers and LVC alarms. Total system weight 10-15kg.

5. RC drives through chains or belts. Highly DYI oriented. Recumperence sells parts. Can have very good weight to power ratio, but no solution is as proven and easy to install and maintain as a hub motor.

 

[jbond]

Been going through the same research. Although I want low weight, robustness and freewheel drag is important to me. On that basis, I don't like the look of the way the Ananda/Cute motors have a split axle bolted up inside the hub. It may not be a problem, but it just looks wrong to me. I also don't like the reports that the Cute freewheels less well than the Bafangs. All of that has led me to dismiss the 2Kg Cute motor.

I don't want to get into the spiral of too much is never enough however as standard and rated these small motors are designed for 15mph-25kmph regulations. So they seem to be designed for a no-load speed of about 20mph. I don't want to be able to do 30mph with assist but having assist drop off at 16mph is too low. There's two ways of dealing with this. Either lace a small wheel motor into a large rim, eg 20" in 26" or run a correct sized motor 26" in 26" and run it at 48v instead of 36v. The problem then is that you end up with more battery weight if you have enough AHr and C rating to handle the current needed.

I also prefer the idea of a rear motor for neatness. And I'd want to run sensorless because it's one less thing to go wrong (and my current sensorless BPM works fine with very little judder at startup)

So I'm thinking of a couple of directions here.
Bafang QWSXH 26" motor, 700c rim. Or 24" in a 26" rim.
36v-15Ahr Ping
Lyen controller or similar, set for 20A (perhaps even 25A)
The small rim motor in the bigger rim gives the extra bit of top speed before assist runs out. The extra current makes up for the loss of torque at lower speeds.

Bafang QWSXH 26" motor, 26" rim.
48v-10Ahr Ping
Lyen controller or similar, set for 18A (perhaps even a bit over 20A)
The extra voltage gives the higher speed. The current is limited to whatever the controller and motor can handle in terms of heat

There's one last battery option that works best at 36v for a bit more money. That's Cellman A123 packs with their LiFePo safety and high C rating compared with Ping batteries and his BMS. I'm thinking of a 12s-1P battery permanently on the bike for 36v-2.3AHr. This is enough for shopping trips and general short distance utility. It's going to be a baby, small, light battery that could be fitted in a frame triangle bag or seat bag. I then have a 12S-4P 36v-9.6Ahr add on battery for weekend jaunts paralleled up to give a total of about 12AHr. It's all the same chemistry, I can use a single charger and the BMS provides all the control.

The last tweak to all this is to use a CA with the extra current limit circuitry to create an "economy" mode that is not speed limited. Set this up for about 100W and add plenty of pedal effort. Allow the speed to rise and fall according to conditions rather than wanting to power over everything at 20mph. And only use the full power for the more brutal hills or when I'm in a rush. Especially with the baby battery, what I end up with is a conventional bicycle that only weighs an extra 4 or 5 KG and rides like a normal bike. But it keeps the average speed up and has a reserve of power to really take the sting out of the hills.

 

[kmxtornado]

So what's happened in the past 9 months?

 

[zukster]

I just received a couple of Cute 100 Rear 26 inch wheel 201rpm kits from BMSbattery.com

http://www.bmsbattery.com/ebike-kits/371-250w350w-q-85100sx-motor-e-bike-kit.html

Although I did not really need the controller, pedal sensors, ebrakes, etc, the kit appealed to me
because it had the hub laced into an aluminum rim already. This alone is worth the extra 50 bucks.

The wheel turned out to be fairly good quality, light, and the spoke are a bit heavier gauge than normal.
It was fairly true when it arrived but since I still use v-brakes, I'm going to take it down to my local
bike shop to adjust it to be as straight as possible.

I didn't really need the controller, but it turns out to be great. Its hall and sensorless if the hall fails, and
it is smaller and lighter than my small 20amp Keywin Infineon controller. This one is limited to 15amps
which is exactly what I wanted for current limitation for my lightweight ebike build. Their technical
support told me that my 14S pack, which is 58.8 volts off the charger, is okay to use, so I'm guessing
it probably has 63 volt capacitors in it.

I've now tried it out with a 12S pack = 50.4 volt max pack and the performance is as good as my
Bafang QSWXH rear wheel hub motor bikes with 15S or 63 volt max packs.

I can't comment on the freewheeling yet because I'm still waiting for my lightweight freewheel to
arrive I ordered on ebay. It was a bit of a torture test going up some steep hills with no pedals, and
after about 10 minutes the motor was not even warm yet. Needs more testing but this is a good
sign so far.

I'll update this as soon as I get the freewheel and chain installed. At the moment, the bike weighs
it at 31-32lbs (my scale is not that accurate). Not bad for a Full Suspension XC Cross Country MTB
Mountain Bike. I use lots of keywords so people will find this when they search

Build:

1999 Rocky Mountain Element Race 19" frame, a few upgraded parts to reduce weight (carbon handlebars etc)
Cute 100 rear motor
15amp controller supplied with kit
2 x 4000mAH Zippy 6S Lipo packs from Hobbyking (20C I think...)
POE seatpost medium size drybag for batteries

Weight of above without Freewheel and Chain = 31-32lbs.

I'm going to write this up with some pictures in a separate thread once I finish the build and get a few
more miles and experience with it.

 

[bumper]

Any updates zukster?

I'm also thinking about a similar setup to that German guy with the stealthy bikes. I'm considering a rear drive Q motor (100 or 128) from BMS battery. I just need enough battery power for a 3 mile ride. There is a grade but it's like 1-2% at a few points; no San francisco type hills at all. And, the person can do lite pedalling.

A few questions. Does it matter if I do a 26” or a 24” wheel? I would like to do a water bottle battery and these 26” MTBs are readily available on craigslist. I understand that smaller 20” wheels can give you low end torque/power, which is what I want, but a battery/controller etc would be more noticeable on a 20” wheeled bike, IMO. I don't want to keep or achieve top end speed.

Finally, is bike weight a consideration? I imagine these cragilist MTBs would weigh between 30-35lbs. The rider would weigh 175lbs. I seem to recall that the german guy had these good brand bikes like cannondale and the like so they were expensive and lightweight.

 

[zukster]

I'm considering a rear drive Q motor (100 or 128) from BMS battery.

Other people on the forum have had problems with the 128 being too wide and were not happy spreading the rear dropout to accommodate. The 100 fits perfect. I've been running one with 14S with the KU63 BMS controller with no problems and its pretty peppy.

I just need enough battery power for a 3 mile ride.

You could even go with 3000 mAH packs or smaller for that distance. I go 20km or so with my 2x6S 4000 mAH packs.

Does it matter if I do a 26” or a 24” wheel?

Not sure what you mean here, but I used the 201RPM wound Cute 100 for a 26 inch wheel. I need the extra torque for hills. It goes as fast as I can peddle on a mountain bike with 11-32 freewheel on the back and a standard 22/32/44 crank triple, so I think this winding is perfect for a normal mountain bike.

I would like to do a water bottle battery and these 26” MTBs are readily available on craigslist.

The water bottle bms battery will work but it is only 10S cells. I would not want to run the Cute 100 and KU63 on less than 12S. I think 10S will bog too much on even small hills.

The lighter the better for the bike. The bike will also handle better. I really like going full suspension for comfort, but a hard tail will weigh less if your back can take it.

I have more info in this other thread you should read:

Edit: I just noticed I put the wrong link below previously. Here is the right link:

http://endless-sphere.com/forums/viewtopic.php?f=3&t=32364&start=45#p576063

 

[DAND214]

The water bottle bms battery will work but it is only 10S cells. I would not want to run the Cute 100 and KU63 on less than 12S. I think 10S will bog too much on even small hills.

Is it LiFePo or LiPo? 10s LiPo is the same voltage as the Life.
As for the the 128 or 100, I hade too many problems with the current 128's.

Dan

 

[d8veh]

I have both Q100s and a Q128 in 4 of my bikes. The Q128 consumes a lot more battery, but doesn't give any more power than the Q100. It's also heavier, so no advantage - only disadvantages.

I really like the Q100. It's very smooth and quiet. At 36v in a 26" wheel it'll do about 18 mph. I have a 24v one in a 20" wheel, and with 12s it'll hold just over 20mph even up slight inclines. I built a bike with twin Q100s front and rear, and it can climb very steep hills with 36v, but it still only does about 18mph. I therefore built another one with twin 328rpm versions front and rear, which was much faster - about 25 to 30mph, but it was very power hungry, which caused both 15 amp controllers to overheat and cut out. The standard controllers are only meant to give about 7amps continuous, but the 328rpm motor wants to take over 10 amps even at low throttle. The motors hardly got warm. So my conclusion is that you need a higher rated controller limited to 15 amps to use the high speed version in a 26" wheel.

I just built another bike with a 250w Bafang in the front, and it's very rough and noisy during acceleration, but smooth and quiet once the load reduces. I preferthe Q100.

 

[motomech]

D8veh,
Are you sure that your battery isn't the culprit?
I run my 328's on the KU63's[modded to 17 Amps] wide open with no cut-outs.
I see about 28 mph on 24" wheels. It will run WO til I'm out of battery.
The controllers get a little warm and I kept them up front in the wind stream.

 

[zukster]

Is it LiFePo or LiPo? 10s LiPo is the same voltage as the Life.
As for the the 128 or 100, I hade too many problems with the current 128's.

Its LiNiCoMnO2. Another safer chemistry compared to LiPo. See:

http://endless-sphere.com/forums/viewtopic.php?f=14&t=26992&start=15#p512285

Also of note. The BMS page lists the discharge rate as 10 amps continuous. Its probably fine for the BMS K63 (which is rated for 15 amps max), but not for a more powerful controller.

Edit: I just noticed I put the wrong link below previously for more information on my tests. Here is the right link:

http://endless-sphere.com/forums/viewtopic.php?f=3&t=32364&start=45#p576063

I really like the Q100. It's very smooth and quiet. At 36v in a 26" wheel it'll do about 18 mph.

That sounds about right. I was guessing I was getting about 25-30km/h on 12S (appx 50V off the charger) and the 14S gives a bit more speed getting up to as fast as is comfortable to peddle. I have not had any overheating problems with either the K63 or Cute 100 at 14S (59V off the charger), so its a nice simple one rear motor setup. I was thinking of trying a 2 motor setup with the faster Cute 100's, just like you did, but I really don't want to go any faster.

I just got a smartphone. I'll get some accurate top speeds from it let everyone know the real numbers on the flats.

 

[zukster]

I run my 328's on the KU63's[modded to 17 Amps] wide open with no cut-outs.

How did you mod them to do 17 amps? That sounds like a nice mod for this compact efficient controller.

 

[d8veh]

D8veh,
Are you sure that your battery isn't the culprit?
I run my 328's on the KU63's[modded to 17 Amps] wide open with no cut-outs.
I see about 28 mph on 24" wheels. It will run WO til I'm out of battery.
The controllers get a little warm and I kept them up front in the wind stream.

I have the controllers side-by-side in a bag, so I guess it's mainly a problem of cooling; however, I've got the same setup on my other bike with 201 rpm motors with no problem. I think I'll have to try mounting them outside, but it spoils the stealthy look, which is important in the UK with our 250w 15mph limit. You can't even see the motors in this photo:

 

[motomech]

I run my 328's on the KU63's[modded to 17 Amps] wide open with no cut-outs.

How did you mod them to do 17 amps? That sounds like a nice mod for this compact efficient controller.

I lightly coat the entire shunt with solder, no globs or build-up. I've done two, both +-.5V at 17Amp.
!7 Amps is the sweet spot for my 328 systems, as it is as quiet as the stk. current[13 to 14A].
Around 18A, the motor starts to protest in the form of a whiny growl.
I rarely run wide open, or even use both motors at the same time for that matter.
This is a pedal bike and I'm happy with the one motor top/cruise speed of 21 to 22 mph.
The second motor comes into play when I'm in a hurry or encounter hills or headwinds. In single fast wind doesn't have much reserve for these and I use the second motor to maintain a certain speed. It's also good if I don't want to downshift. Without the second motor, I would be doing a lot more shifting.

 

[bumper]

I'm considering a rear drive Q motor (100 or 128) from BMS battery.

Other people on the forum have had problems with the 128 being too wide and were not happy spreading the rear dropout to accommodate. The 100 fits perfect. I've been running one with 14S with the KU63 BMS controller with no problems and its pretty peppy.

Looks like I'll go with the 100.

I just need enough battery power for a 3 mile ride.

You could even go with 3000 mAH packs or smaller for that distance. I go 20km or so with my 2x6S 4000 mAH packs. [/quote]


This is lipo, right? I'm a little nervous setting up this bike with Lipo due to the potential fire issues.

Does it matter if I do a 26” or a 24” wheel?

Not sure what you mean here, but I used the 201RPM wound Cute 100 for a 26 inch wheel. I need the extra torque for hills. It goes as fast as I can peddle on a mountain bike with 11-32 freewheel on the back and a standard 22/32/44 crank triple, so I think this winding is perfect for a normal mountain bike. [/quote]


Everyone seems to be doing these cute motors on 20" or so smaller diameter wheels. Wasnt sure if a 24" rim would give me better low end torque since it's a smaller diameter. Good to see that you are doing yours on a 26". 26" it is!

I would like to do a water bottle battery and these 26” MTBs are readily available on craigslist.

The water bottle bms battery will work but it is only 10S cells. I would not want to run the Cute 100 and KU63 on less than 12S. I think 10S will bog too much on even small hills. [/quote]


I like this safer battery technology that BMS has. Anyone sell a water bottle battery with 12s? I could try to jimmy a bottle cage and a aluminum thermos and DIY one too.

The lighter the better for the bike. The bike will also handle better. I really like going full suspension for comfort, but a hard tail will weigh less if your back can take it.

I have more info in this other thread you should read:

Edit: I just noticed I put the wrong link below previously. Here is the right link:

http://endless-sphere.com/forums/viewtopic.php?f=3&t=32364&start=45#p576063[/quote]

 

[zukster]

I lightly coat the entire shunt with solder, no globs or build-up. I've done two, both +-.5V at 17Amp.
!7 Amps is the sweet spot for my 328 systems, as it is as quiet as the stk. current[13 to 14A].
Around 18A, the motor starts to protest in the form of a whiny growl.

That's some pretty nice testing. I might do a second motor at some point as a fail safe. 2 motors, 2 controllers, 2 battery packs. Do you use two throttles? I peddle mostly but I use my epower to go farther than I normally would. I'd hate to loose power 50 miles from home in a cold Vancouver, BC downpour. Shudder :|

What kind of battery packs and max volts are you using? I've also tried a KU63 with a 15S Lipo pack which is a maximum of 63 volts off the charger, but in fact is never really over 62 volts since the cells tend to drop a bit as soon as they're taken off the charger. One of the limiting factors of the KU63 is a 63 volt capacitor inside. So a 15S Lipo pack at 62 volts is just within its limit. I went to a 14S pack as my daily driver just to give it a bit more grace but I've never actually measured the current under full load yet. When I first started using 14S I would hop off the bike and feel the motor and controller quite a bit, especially after big hills, and they have always been fine. I really should get a watt meter to better test.

Regarding modifying the KU63, I've wondered if upgrading the 63 volt capacitor and possibly the Mosfets might be worth trying to squeeze a bit more pep out of a Cute 100 with say a 16S pack. I don't really know enough about electronics to try this and I've been pretty happy with the stock KU63 and Cute 100 on 14S.

I know you can only push these small motors so far. I also have some rear Bafang SWXH's. They were always fine with a 20 amp Keywin Infineon controller up to 15S (again 63 volt capacitor in controller). But I just had to want a bit more so I got one of ebikes.ca nice 25 amp/6 Mosfet controllers. At 18S and pulling a trailer I burnt out one of the Bafangs when pushing it too hard. I wasn't really that surprised. It got too hot for the windings as well as the nylon gears. So I changed my trailer setup down to 16S and installed 3 metal gears in the Bafang to keep them from melting if I do want to push it a bit from time to time. So far so good. Anyway, my thought was that perhaps 14S or your tested 17 amps is about as far as you want to push a Cute 100...

Now you just have to figure out how to ABS your two wheel motor setup

 

[zukster]

I just need enough battery power for a 3 mile ride - You could even go with 3000 mAH packs - This is lipo, right? I'm a little nervous setting up this bike with Lipo due to the potential fire issues.

yeh, just stick with a safer tech then. I used to use the Canadian Tire Yardworks batteries and worried less. They were Lithium Cobalt Manganese I believe. Now I charge my Lipos outside on the concrete. Check out what ebikes.ca carries. They only carry quality safe well tested batteries. They also host this site