800W Q128c commuter build

The PAS will only work when you pedal in one direction. The direction depends on which way round you assemble the magnet disc. You can't go by the arrows, so you have to try it to see which way it works. Normally, I install the sensor, then I place the magnet disc on the spindle, switch everything on and turn the pedal to see which way it works. It's easy at that point to flip the magnet disc. I know many people that assembled everything and made the crank nice and tight, only to find out later that it worked backwards.

One time, I changed the controller on an OEM ebike. I was disappointed when the PAS didn't work, but later, I discovered that it worked backwards, so I had to take the crank off and flip the magnet disc.

Some PASs are handed. They will only work in one direction. If you flip the magnet disc, they still don't work.

To summarise all the possibilities: There's 4 combinations of magnet orientation and direction. In all cases, one combination will work. In most cases, two combinations will work. In some cases, different controllers will reverse the combinations.

This seems a good time to post an update + possible future plans here, as there seems to be considerable interest lately in the Q100s and Q128s. It’s been just over a year since completing this build, and I have clocked about 5000 km without any problems other than the odd flat tire.

I enjoy pedaling hard during my 28 km 2-way work commute, and use the motor only to augment my speed/acceleration and complete the trip in a reasonable amount of time. I tried PAS but did not like being unable to limit the thrust in real-time. The left hand thumb throttle allows me a constant modulation of power input as I ride, change gears with my right etc. I limited the wattage to just over 500W, which oddly, was the lowest possible setting on the "500W" S12S controller. This 500W was all I needed to maintain at least 25 kph even on the steepest hills on my commute and max out the motor speed/RPM 70% of the time. With higher (800-900W) wattage, I found I occasionally over amped the motor on steep hills when stressed to beat traffic, causing it to protest with a high pitched whine.

At present, my 260rpm (at 48V in 700c wheel) has become woefully inadequate, in that I spend most of my ride (controller limited to 500 W) having maxed out the motor RPM on flats and even slight uphill section; I find myself wanting more top end assisted speed. I like the Q series geared hubs, as they are tiny to the point of being barely noticeable; for their price, and having lasted over 5000 km with no sign of failure, they seem reliable enough under the loads I operate them.

I’m thinking of ordering the 328RPM Q128c (at 48V) https://bmsbattery.com/ebike-kit/768-q128c-135mm-500w-rear-driving-ebike-hub-motor-ebike-kit.html#/43-voltage-48v/214-rpm-328. I know for most, a 328RPM motor in a 700c wheel is a bad idea, but in this case, I believe it will work with my aggressive riding style. It will allow me to better match speed with traffic on the section of my commute on the busier but gently sloping streets.

I’ll definitely order an extra S12S controller while I’m at it; the S-LCD6 LCD Meter for S-Series Controllers looks interesting, as it will take up less real estate on the handlebars, but little information is available from BMSB regarding compatibility, programmability and features.

I’m also thinking of upgrading the battery to something higher density that I can hide in a bag for a stealthier appearance. A 52V (14s) seems to be compatible with these S12S controllers by many accounts. The EM3ev batteries built from high capacity cells (33G or LG MJ1) interest me, and a 14s 4p setup would discharge at about 0.7c with a 500W input at 50V, and weigh a respectable 3.4kg. Total Ah of around 12.5 would give me approximately 60 Km range based on my current max range of 50 km with my typical riding style. I’d have to ask Paul to custom build this, as they only stock the 5p versions. I'd keep the BMSB 48V 11.5Ah Panasonic bottle battery as a backup.

Coupled with a 52V battery, the 328RPM version should max out at around 50 kph and be happy enough at 25 kph for the hilly bits.

IMHO, a 328rpm Q128 in a 700c wheel is a bad idea. It'll have terrible efficiency at 25 km/h. Only do it if you have a light steamlined bike that you want to ride continuously over 32 km/h.

Rather than the S12S, they have some nice 48v batteries with 2oA sine wave controllers included thst are a perfect match for the Q128; however, if you don't use PAS, that seems like overkill. The cheaper KU93 controller would be sufficient.

d8veh said:

IMHO, a 328rpm Q128 in a 700c wheel is a bad idea. It'll have terrible efficiency at 25 km/h. Only do it if you have a light steamlined bike that you want to ride continuously over 32 km/h.

Rather than the S12S, they have some nice 48v batteries with 2oA sine wave controllers included thst are a perfect match for the Q128; however, if you don't use PAS, that seems like overkill. The cheaper KU93 controller would be sufficient.

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Thanks for the reply and for posting this. I agree a 328 in a 700c wheel is a bad idea for 95% of people; still there are those for which this setup works well: they have few hills and mostly pedal, augmenting with limited motor power.

I also saw in another thread (still looking for the link) that if you run at reduced throttle, the motor will be happier at lower RPM.

Wow, has it been a year already???

Yeah, I do the 328 @ 36v, so I think a 328 at 48v should work fine, if your ride is flat and you are willing to work too. That is basically the same as taking a 36v260rpm motor and running it at 48v. Dave is right, you want to be spending 90% or more of your time over 35km/hr – below that it will be inefficient. But for a few fine people, it can work.

(Again, a 700c wheel does much better with a 328rpm motor than a 26” wheel. They have almost the same diameter, but the 700c wheel is a lot more efficient (about 60 watts less rolling resistance) and tends to be on a bike with less air resistance. Personally, I like a slower Cute (~260rpm) for a mountain bike, and the 328 for 700c wheels with good tires.

For your throttle question, at 30km/hr you draw 20 amps at full throttle (if you have it), back off to 75% throttle and you draw 9 amps. Current isn’t linear with motor speed, it depends where you are relative to the current peak.

chas58 said:

Wow, has it been a year already???

Yeah, I do the 328 @ 36v, so I think a 328 at 48v should work fine, if your ride is flat and you are willing to work too. That is basically the same as taking a 36v260rpm motor and running it at 48v. Dave is right, you want to be spending 90% or more of your time over 35km/hr – below that it will be inefficient. But for a few fine people, it can work.

(Again, a 700c wheel does much better with a 328rpm motor than a 26” wheel. They have almost the same diameter, but the 700c wheel is a lot more efficient (about 60 watts less rolling resistance) and tends to be on a bike with less air resistance. Personally, I like a slower Cute (~260rpm) for a mountain bike, and the 328 for 700c wheels with good tires.

For your throttle question, at 30km/hr you draw 20 amps at full throttle (if you have it), back off to 75% throttle and you draw 9 amps. Current isn’t linear with motor speed, it depends where you are relative to the current peak.

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I've been busy for a while working a second job, and haven't had much time for fun. At least I get an hour a day ride for the work commute and the weather has been nice. Time sure does fly, and I'm very pleased with the Q128c motor - lean but still mean.

I'm guessing that since I programmed the S12S controller to max out at 10A (lowest C5 setting), there would be little difference in amperage between 75% and 100% throttle at any speed?

I'm still torn as to whether to go 328. I pedal like an animal, and for half my commute, I'd definitely be increasing my top speed, as I'm going 38 kph and the motor is contributing less than 50W at full throttle. Sections of my commute feature roads so rough I take a pop the panniers out of the rack type pounding even at 20-25 kph; I'm almost thinking a Giant Anthem with 700c road rims/tires and an oversized crank might be in order...

Every day I think about the terrain, the commute and the question of how to get the most out of the light but fast builds.

I'm thinking the worst that could happen is I burn out a $100.00 motor or a $20.00 controller and have to pop in a spare - nothing ventured nothing gained

I just recently converted my bike with a Q128C. I love it. It's powerful, smooth and silent. I'm using the 36v 201 rpm one at 48v with a 14 amp sine wave KT controller. I get a top speed on the road of about 38km/h with 26"wheels. I think the most suitable controllers,if you want more power, are the 17A and 20A sinewave ones you get from PSWpower.

d8veh said:

I just recently converted my bike with a Q128C. I love it. It's powerful, smooth and silent. I'm using the 36v 201 rpm one at 48v with a 14 amp sine wave KT controller. I get a top speed on the road of about 38km/h with 26"wheels. I think the most suitable controllers,if you want more power, are the 17A and 20A sinewave ones you get from PSWpower.

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I'm glad you're liking the Q128c; definitely impressive power relative to its size. I'll definitely look into one of those PSWpower controllers, for as soon as time permits and I find a suitable frame, I'll be working on Q128c commuter gen2!

I decided to try and see just how long a Q128c would last when run at baseline specs of 550W, and now I may have my answer. Today at just under 6300 km, the motor started to make a constant high pitched singing sound, which increases in pitch along with speed. It seems like the clutch is failing and the gears are constantly in motion powered or unpowered.

At any rate, I think a new motor will be on order. The big question is whether to stick with Q series motors knowing they will last a year and a half at best, or to try a (hopefully) hardier geared motor? Really, if a different motor lasts 15K but costs three times as much, I'm no further ahead. The idea is to keep it light and nimble.

molybdenum said:

I decided to try and see just how long a Q128c would last when run at baseline specs of 550W, and now I may have my answer. Today at just under 6300 km, the motor started to make a constant high pitched singing sound, which increases in pitch along with speed. It seems like the clutch is failing and the gears are constantly in motion powered or unpowered.

At any rate, I think a new motor will be on order. The big question is whether to stick with Q series motors knowing they will last a year and a half at best, or to try a (hopefully) hardier geared motor? Really, if a different motor lasts 15K but costs three times as much, I'm no further ahead. The idea is to keep it light and nimble.

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Nearly every time I open a defective motor, it's rusty. Maybe you just add a clean and regrease to your maintenance schedule every 5000km. You should at least open yours to see what's wrong with it it for the sake of the knowledge base. If is indeed rusty, you could think about some counter-measures on the next one.

OK I'll open it up tonight and have a look and post pics; got a fresh can of grease for it. Since clutch failures are usually in the always disengaged mode, it could be seizing up? However, we have not had a drop of rain in the past three months. I agree with the 5000Km overhaul, but the cover plates are a PITA.

For those coming across this thread, here is a link to a thread discussing various removal techniques for a Q100 cover plate; I'm hoping the Q128 can be removed similarly... we'll see...

https://endless-sphere.com/forums/viewtopic.php?f=2&t=88303&p=1288267&hilit=q100+cover#p1288267

All these motors with screw-on side-plates come apart much more easily if you heat up the hub with a hot air gun until it's just about too hot to touch.

Heat gun ready, unfortunately, the plywood tool folded so without metal fab facilities, I'm employing cave tools and slowly grinding my way to a more substantial steel removal device. I've ordered another Q128c today, and we'll see I get the cover off before it arrives - I give it even odds...

Any one know if the threads loosen clockwise or counterclockwise as per the pic below?

Counter-clockwise to remove. Clockwise to assemble.

I finally got the cover plate off; the only thing holding me back last week was that I couldn’t find the metric bolts I needed (in a metric nation no less ). I was in Rona today to pick up some sandpaper for a cabinet I’m making, and I saw a pitiful collection of metric nuts and bolts. The metric bolts I needed were all gone but they were all hopelessly mixed up; I ended up finding them in other bins. I built a tool with metal struts much like that of ntr but twice as thick, then used my hard earned 20 mm bolts to fix the tool to 2 of the 3 metric screw holes behind the cassette. Pulling counterclockwise against the laced wheel indeed loosened the cover plate after heating the motor to 60-70C with a heat gun.

Unfortunately, my cell phone stopped working - so no camera. Since my spare motor arrived from BMSB, I opted to swap the guts of the new motor into the old shell laced to my wheel and save the tear-down and lube job for when I have a working camera. This time, the new motor was mounted to a piece of plywood using a spare disc rotor (thanks zukster), then fixing the tool to the other side as per the wheel-mounted motor above.

At a cursory glance, the grease inside was clean, there was no corrosion and the gears looked to be in good condition. I’m eager to strip down this motor and try to see what could be causing the gears to spin when unpowered and pedaling. I have a tub of lithium grease waiting for the clutch once I get a camera to get some good pics.

As for the phone, after some troubleshooting and purchasing an unnecessary battery, I traced the problem to the EMMC power IC chip, which nobody will repair of course - ebay to the rescue; I have one in the mail from Great Britain for $3.99 CDN inc shipping. If anyone has pointers on microelectronics soldering, it would be greatly appreciated - *makes mental note to never buy a Samsung again

if the clutch is sticking, I'll guess/predict one of the roller springs ground down and became wedged between roller/drum. Akiema used springs more suitable for ballpoint pens than a bicycle motor, IMO. I eventually found some much hardier, heavier gauge springs which slowed this problem down but eventually other issues cropped up as mentioned previously in this or similar Q (Akiema) motor threads.

Bottom line IMO - these motors were originally designed 36V/350W continuous power/speed. And probably never intended to be used/ridden by 200-250lbs folks.

molybdenum said:

I finally got the cover plate off; the only thing holding me back last week was that I couldn’t find the metric bolts I needed (in a metric nation no less ). I was in Rona today to pick up some sandpaper for a cabinet I’m making, and I saw a pitiful collection of metric nuts and bolts. The metric bolts I needed were all gone but they were all hopelessly mixed up; I ended up finding them in other bins. I built a tool with metal struts much like that of ntr but twice as thick, then used my hard earned 20 mm bolts to fix the tool to 2 of the 3 metric screw holes behind the cassette. Pulling counterclockwise against the laced wheel indeed loosened the cover plate after heating the motor to 60-70C with a heat gun.

Unfortunately, my cell phone stopped working - so no camera. Since my spare motor arrived from BMSB, I opted to swap the guts of the new motor into the old shell laced to my wheel and save the tear-down and lube job for when I have a working camera. This time, the new motor was mounted to a piece of plywood using a spare disc rotor (thanks zukster), then fixing the tool to the other side as per the wheel-mounted motor above.

At a cursory glance, the grease inside was clean, there was no corrosion and the gears looked to be in good condition. I’m eager to strip down this motor and try to see what could be causing the gears to spin when unpowered and pedaling. I have a tub of lithium grease waiting for the clutch once I get a camera to get some good pics.

As for the phone, after some troubleshooting and purchasing an unnecessary battery, I traced the problem to the EMMC power IC chip, which nobody will repair of course - ebay to the rescue; I have one in the mail from Great Britain for $3.99 CDN inc shipping. If anyone has pointers on microelectronics soldering, it would be greatly appreciated - *makes mental note to never buy a Samsung again

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I'll definitely have a good look at the roller springs when I perform the tear down. It'd be great to find some beefier ones. For documentation purposes; although the thread is titled "800W commuter build", I tested a variety of powers and eventually opted for the lowest setting on the S12S controller for an output of 550W on full charge - this is all I needed since I like to pedal. For most of my ride, the power output is considerably less as I'm either easy on the throttle or am pedaling/riding at 40kph - near the motor's unloaded speed. I'm about 175lb and usually travel with an additional 10-15lb in the panniers. Certainly this motor has been babied. All in all, it lasted 6248 km before showing any clutch problems, at which I limped home and stopped riding immediately.

Interestingly, there were changes to the motor from the 2 yr old version. Gone is the old smooth inner aluminum shell; the inner shell now has heat sink-like fins to better shed heat through increased surface area. This still fit the old casing just fine, so there was no need to re-lace the wheel.

Still no phone camera, and with a working bike, it will probably be a couple weeks before I get around to the dissection & will provide photos.

Ykick said:

if the clutch is sticking, I'll guess/predict one of the roller springs ground down and became wedged between roller/drum. Akiema used springs more suitable for ballpoint pens than a bicycle motor, IMO. I eventually found some much hardier, heavier gauge springs which slowed this problem down but eventually other issues cropped up as mentioned previously in this or similar Q (Akiema) motor threads.

Bottom line IMO - these motors were originally designed 36V/350W continuous power/speed. And probably never intended to be used/ridden by 200-250lbs folks.

Click to expand...

molybdenum said:

I tested a variety of powers and eventually opted for the lowest setting on the S12S controller for an output of 550W on full charge - this is all I needed since I like to pedal.

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Would that mean that an S06S (8A rated, 17A peak) @ 48V would be sufficient to drive the Q128c?

If I can trust Strava with providing reliable enough grade data, then the utmost that I'd ever want to use a motor on is an average incline of 15% over, say, 100-200 metres. "Normal" would be something like, on average, 5%.

I think it's crazy that for a "500W" controller, you can't even dial down the S12S to 500W at minimum settings(though around 550W is close enough to my needs). I've never heard of anyone trying the S06S controller with the larger Q128c, which in themselves, are quite finicky about their controllers. I thought of using the S06S and I see no reason why it wouldn't work, though I'd want a backup S12S before trying. - maybe others could chime in? I stuck with the larger S12S as limiting amps and riding at low throttle are surprisingly hard on controllers. The extra beefiness and heat shedding capacity should work in my favor with the larger S12S controller; I stuffed it in a bag, and it has been fine even on the hot days - I do have an extra S12S backup controller however.

At 800-900W, my motor was fine on the flats. If I accelerated hard up a steeper grade (~10%?), my motor would sometimes make a high pitched zinging sound, which never occurred at 550W. Note that I use throttle only, and PAS (or a lighter touch on the throttle) may be the way to go in these situations.

daffy99 said:

Would that mean that an S06S (8A rated, 17A peak) @ 48V would be sufficient to drive the Q128c?

If I can trust Strava with providing reliable enough grade data, then the utmost that I'd ever want to use a motor on is an average incline of 15% over, say, 100-200 metres. "Normal" would be something like, on average, 5%.

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The S06S works fine with the Q128, except that it's only 36v, so you get less power. I'm running my Q128c with the 48v version that I got from Aliexpress. The 17A and 20A versions from PSWPower are somewhere in between, so one of those would probably suit you.

d8veh said:

The S06S works fine with the Q128, except that it's only 36v

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Oh, indeed!

I need to become much more disciplined in scrutinizing every little bit of the specs across all these Kunteng versions. It's a total mess. Luckily, I got myself one of the pswpower controllers, just for the heck of it, but instead of 10A rated load as show on the photo, they delivered 8A rated load .

And bmsbattery really do not like me asking about "are these connectors really waterproof". Or telling them that the LCD2U - i.e. one with USB not listed on their website - is priced a tad on the high side. Sigh.

I wonder whether the Q128c is really worth all the bother, and, on top, the rather substantial amount of money _after_ custom tariffs, value added tax, and local logistics fees have been added. I am convinced that I want a low rpm geared hub motor, but I have no clue what exactly makes a Q128c (at 15A max load) better than anything else, all other things being equal (battery, controller, display).

(Apologies for the rambling.)

daffy99 said:

I wonder whether the Q128c is really worth all the bother, and, on top, the rather substantial amount of money _after_ custom tariffs, value added tax, and local logistics fees have been added. I am convinced that I want a low rpm geared hub motor, but I have no clue what exactly makes a Q128c (at 15A max load) better than anything else, all other things being equal (battery, controller, display).

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Definitely worth it. In my search for ebike nirvana, I've built about 10 bikes for myself and each has been through several different iterations with different motors. I've also built about 10 bikes for other people. I help out at the local ebike shop and I go to every bike show where I test anything new. That includes all the expensive high-end bikes. If I could find something better, I would buy itas I have enough money. It's only a question of how much power you want and how fast you want to go. In order of power: Q100c - Q128c - Ezee - MAC. I don't want an electric motorcycle, so I don't want the weight of anything heavier than a MAC. I tried a generic 1000w DD motor, but the bike was just too heavy. I could hardly lift it over the step in my porch to get the bike out. Bear in mind that my ideal speed for travelling is 22mph. For those that want to average 30 mph, a DD motor is probably the way to go.

I can see where the Q128 would be a great compromise in terms of size weight and power.
Before the new revised version came out, I ended up building two bikes to cover what i wanted in a ebike.
My 2WD does it all. it has speed(27 mph), range(40 to 50 miles) and reliability. It also weighs a ton. I probably could have used just the rear Ezee V1, but I like to run it low power so the PAS is smooth and the frt. Q100H adds "snap" when I want it. But it's more like an electric mini-bike than a bicycle and not very stealthy;



To make an "assist bike" that was stealthy, I went w/ a single Q100 rear. Since I am a "big" guy, I had to use the low-speed "201" motor to aid acelleration and climbing, but on 12S LiPoly(44V), it is slow (18 to 19 mph). I does force me to pedal though;



A Q128 is just enough more motor than the Q100, that it would let me run a single mid-speed for a good compromise Assist bike w/ enough speed to be fun(22 to 23 mph).
For a little more power and speed, I think a Q100/Q128 mid-speed 2WD would make a really neat bike.

I blew [strike]three[/strike] four spokes on the rear wheel today after hitting something nasty on my way home from work. Oddly, they are broken at the hub elbow and at three different places around the wheel; as a result, the wheel is around 2 cm out of true and wobbling badly.

I hope to stop by Grin tomorrow and pick up some more spokes. I'm wondering if I can replace the spokes and re-true or if I have to re-lace the whole wheel?

They broke at the elbow? This is often a sign that the spoke hole diameter is too large for the spokes. What diameter are the holes and which spokes are you using?

Coincidently, I was wondering about the same thing in relation to this motor just a few days ago.