2 Speed Xiongda hubmotor

[mountain biker]

wow very cool....I feel like I am making up on all the high school science classes I didn't go to and obviously college level and ma and phd level. I really appreciate your all help....it really seems like for just a simple vehicle there are a lot of complex calculations in this vehicle just to get it to go faster than a jog. okay now why would a 12 s make it go faster...I am not quite understanding that isn't 36 volts 15 amps. the same power if it is 13s 12 s or 10 s....and what does this number s mean anyway> and how does this make the double speed motor faster....how can it make it go 20 percent faster...I get the higher voltage making the rpm kick.....

and why doesn't this motor just catch on fire 36 volts 15 amps...300 nominal watt motor....that's like 500 watts double its nominal rated power almost..or techincially 166 percent more than rated nominal watts...can the sorry(liushu controller limit the watts).....the one that is recommened by the factory?

 

[spinningmagnets]

...why doesn't this motor just catch on fire...500 watts double its nominal rated power...

The factory "rated" watts don't count. This is one of the main reasons forums are so valuable...what can they actually do? Some companies want to say their motor is "legal" in a country that has a 250W power limit (word gets around quickly that is capable of much more). And on the other end of the spectrum...there are companies that have claimed their motor works great at 3,000W continuous, and their 10-Ah generic lithium-Ion battery can do 30 miles.

 

[docnjoj]

Your question seems to read " Why does higher voltage make a bike motor go faster"? Higher voltage makes more watts and gives higher RPM. It simply gives you more power. Since amps=heat, higher voltage is more efficient than more amps for a given number of watts. I constantly run 500-600 through my 2-speed and it stays quite cool (measured) I think you could safely run 1000 watts for brief periods of time. 12S Lipo is 44 volts nominal and close to 50 volts charged. 12S LiFePo4 is about 36 volts nominal, much less voltage.
otherDoc

 

[mountain biker]

appreciate that...wow this motor is kinda neat allow it to run 500 600 watts and no issues with heat...you said you measured the temp heat. does the linshui controller do that for you and is there an auto shut off if it gets too hot...also with that controller that the factory suggests .////what does programaable mean...does that mean I can control amps like I can say 5 amps 39 v olts or something....I appreciate everyones feedback....and how many miles have you guys put on this thing. I think gm says 36,000 miles for trany and engine..whats this one done for you guys so far. anyone take it offroad? maybe 1000 watts or something...it seems like this motor can keep getting pushed upand up...ofcourse....

with this controller then my nominal voltage of lifepo4 bATTERY SAY IS 36 VOLTS BUT IT CAN READY 40 VOLTS OR SOMETHING...DOES THE CONTROLLER RUN IT AT 40 VOLTS OR DOES IT KEEP IT AT 36 VOLS? COULD I PROGRAM OR EDIT THE CONTROLLER TO MAKE THE SET UP HERE 48 VOLTS IF I ONLY HAD A 36 VOLT BATTERY PER SAY? LIKE THE DC TO DC BUCK CHARGER OR THE MPPT TYPE CONTROLLER

 

[docnjoj]

Don't know about the auto-shutdown with the Lishui since I have the newer KT controller. I believe it has an over-ride thermal shutdown but am not sure. Probably one of the engineers like D8veh could answer that. I just discovered that on level ground I believe you can get to 12-16 mph faster by keeping the speed switch in High power even from a standing start. You still need low for steep hills. This is with a 20" wheel. YMMV.
otherDoc

 

[menvert]

DOES THE CONTROLLER RUN IT AT 40 VOLTS OR DOES IT KEEP IT AT 36 VOLS? COULD I PROGRAM OR EDIT THE CONTROLLER TO MAKE THE SET UP HERE 48 VOLTS IF I ONLY HAD A 36 VOLT BATTERY PER SAY? LIKE THE DC TO DC BUCK CHARGER OR THE MPPT TYPE CONTROLLER

I don't see it as likely that the controller has a buck converter these things generally run constant voltage, variable current.
I was curious myself about what the upper "safe" voltage limit is on the 36v controller is (the current KT which is the only one they want to sell now)

I myself have been searching for a 30-40amp (enough to deal with peak amps) buck converter so I could have a 48v battery with variable output voltage from 36 to 48, but it looks like for that sort of amps you need some serious gear... the best I found did about 10 amps so you'd have to go to the trouble of putting 3-4 in parallel and they need some heat sinks from the description... all in all probably getting close to $100 for that and it'll be a bulky bit of kit + I am not an expert and the risk of blowing myself up is a bit prohibitive...
Probably easier to get a 36v battery with an add-on 12v of the same chemistry/Ah to achieve this...

 

[menvert]

Got my XD today, very excited - weight is exactly 3.21 kg (7.077lb), wheel building is going better than expected and thankfully the spoke calculator was correct too
Delivery is very fast, 6 full days (not business days)

 

[Alan B]

Motor controllers are already effectively "buck converters", so not much point in adding one in front of another.

 

[menvert]

Motor controllers are already effectively "buck converters", so not much point in adding one in front of another.

Maybe my definition of buck isn't accurate, but none of them change the voltage delivered do they? it's constant voltage = to battery isn't it?
The question was regarding do the controllers modulate voltage? so you can attach a 48v battery and the controller lowers it to 36v? I think no controllers do that right?

 

[Alan B]

Controllers do PWM into a coil (the motor inductance). This effectively reduces voltage (it produces the same result in motor torque and speed as reducing voltage).

 

[menvert]

Controllers do PWM into a coil (the motor inductance). This effectively reduces voltage (it produces the same result in motor torque and speed as reducing voltage).

yeah ok, I don't think you understand the question..., unless you're saying you can pump as much battery voltage as you like and the coil automatically limits it to it's max...

 

[Alan B]

Coils don't care about voltage. Coils make magnetic fields from current. The voltage in a coil doesn't really matter unless the insulation fails.

B = u0 * I / (2 * pi * r)

The voltage is not involved. Field is proportional to current.

 

[menvert]

yeah ok am no expert, but in respect to the question... if coils don't really have a voltage cap; do controllers and their mosfets have a realistic voltage limit? is running my 36v controller with a 48v battery generally gonna kill it, I think that's the real question we'd like someone with Alan B's expertese to answer?

 

[d8veh]

A 48v battery will normally kill a 36v controller sooner or later. 12S lips are OK though as the voltage approx 4v lower.

 

[Alan B]

Yes, controllers are designed for a particular voltage and exceeding it is not advised. Get a controller with the appropriate voltage rating.

 

[chas58]

I think these motors are ideal for Europe but riding conditions over here in the US often require more speed to navigate traffic that's largely unused to seeing bicycles on the road at all. At 15 mph I feel like a slowly moving speed bump a lot of times here, some two lane roads I ride on have 55 mph speed limit and cars going 60+ all the time.

It would be interesting to try one of the fast wind motors in a 700c rim on 48v in a lightweight roadie/fast commuter type bike to assist someone who wants to actually pedal some, that sounds like a nearly ideal use for a small motor like this

Good point!

That is pretty similar to what I built and ride. But, I’m using the old stand by Cute Q100 at 300rpm. Top speed of either motor would be the same (probably around 25mph steady state with this size motor). The draw backs of my build are:

1) You need to be a pretty strong rider to accelerate and help the motor
2) My build doesn’t do great in hills (which personally I don’t need).

The two speed motor takes care of those two issues. Still, with a motor that takes about 15 amps or a little more, it’s not going to do much over 20mph without some help. The two speed motor is going to help more with low speed than top speed.

 

[Alan B]

There's some strange things being said recently, so let's try and clear some things up.

The weight is slightly more than a Bafang SWX because it has the double clutch and extra pinion. Unfortunately I built my last one into a wheel yesterday, so I can't weigh it, but I would estimate the weight at somewhere between 3kg and 3.5kg.

I'm talking about the 36v one at 20A, which I can imagine is very similar to the 48v one at 15A. The following statements are for throttle only - no pedalling.

If you put the switch to low gear and accelerate from a stop, it will draw its maximum current until you get to about 8mph, and then the current ramps down until it's zero at about 12 mph, so you can't go any faster. It makes good power and torque up to about 10 mph, which is the speed it will hold on a slight incline. It will manage a 14% hill without pedalling with 110 kg on board and a bike with all-up weight about 27kg.

With the switch in high gear, it behaves exactly like a Bafang SWX at the same current, i.e. it'll draw maximum current up to about 13 mph and then it ramps down to zero at about 20 mph, which is its top speed. It makes good power and torque up to about 17 mph. It'll hold about 15mph on a slight incline.

In automatic mode, if you start from a stop, you get good acceleration initially, but then you feel it run out of power at 10mph because the current decreases. The controller senses that, so it changes gear, and then you get maximum current again, so you get new acceleration.

If you're light and your rides are flat, this motor would be the wrong one for you because it would never be in the low gear. Its strong point is that it can get heavy/weak people up steep hills by using its low gear. My tests don't show it to be any more efficient than a larger geared hub-motor. It's only advantage is that it's smaller and lighter and has a lower nominal rating, but can still get you up those steep hills without overheating, though more slowly than a bigger geared motor. It can maintain good torque right down to about 3mph. It could also be useful for those that want low power high speed setup by overvolting it to raise the gear-change point. My ones change at a proportionally higher point if I increase the voltage. This would solve the problem of poor efficiency at low speeds that you get with other low power high speed motors.

Thanks for an excellent summary for this motor, missing only the wheel diameter. What wheel diameter was it?

I would like to setup a folder with a small motor and keep it light. Unfortunately there are some steep hills, so this may be the only game in town.

 

[cwah]

It could also be useful for those that want low power high speed setup by overvolting it to raise the gear-change point. My ones change at a proportionally higher point if I increase the voltage. This would solve the problem of poor efficiency at low speeds that you get with other low power high speed motors.

didn't you say the controller isn't working very well when overvolted? I'd love to have a small motor like this with a 30mph top speed and good torque

 

[menvert]

So I got my build mostly complete, lacing into a 700c rim was not so hard in the end, getting it to fit the standard 135 dropouts on the other hand...
Mixed reviews overall I have to say; It looks like they gave me the setup I asked for; 145mm disc version @280RPM instead of about 230, running - 36v LiFePO4, 700c

I get just over 15/30kph. Probably because I have non-standard RPM the Auto function just doesn't work properly, it keeps changing down at 20kmh when the Watts gets to about 500, just after powering in the high gear, Also It seems to be able to pull more Watts in low gear than what others reported (400w)

I love having the Voltage and Watts on the KT-LCD3 screen (after I figured out how to program the settings, anyone know what P1-P6 do?)
The Motor runs nicely though, I little bit noisy, but not really loader than my old single speed, it only has 2 pin brake cut-offs, and the ones I ordered are 3 pin ones that fit on the end of the brake cable, so I'll have to attach the 3rd pin, constant 5v to say the PAS 5v

The KT controller runs fairly hot and I am not used to the Sine Wave controller, which basically means I have lost the instant power I had on my last build.
The time to change gears (almost a whole 2 seconds, then the sine has to build back up to speed) makes it pretty unusable unless you can pedal a fair bit during changes, I mean going 15kmh on a hill then when it finally changes I am now going 10 because of how long it took...

So yeah as was posted a little while back, it really is more suited to a heavy setup (even with my higher RPM model), whereas mine is light weight (24kg). but today was my 1st commute (currently averaging just over 25kmh compared to my old heavier single speed setup which was 23.66), let me see how it goes when I get used to it, and install my shorter cranks so I can pedal more.
In retrospect I probably should have gone 48v for this purpose I reckon, so I might buy a replacement 48v controller when it's time for my new battery, and from the weekend discussion it sounds like this won't tax the Motor to do so, Or plunge in the deep end and try to make an full Arduino controller (yeah beyond my skills but sounds fun to try)

I might post my build in another topic, with pics, once I get settled with it. still an impressive kit.

EDIT: Another thing to note - the supplied disc mount screws are too short and resulted in stripping the first few mm of thread in 3 of my holes, as they were too shallow (not much force was applied either)
Using the longer original bike screws with a couple of washers and it seats fine though, but never nice to have
EDIT 2: Yona tells me the supplied screws and plastic ring aren't for mounting the disc, but rather for when disc is not used...

 

[menvert]

I found a detailed KT-LCD3 manual explaining all the Extra programming codes (P1-P5 & C1-C12)
(Enter standard programming by turning on and within 5 seconds hold Up+Down. To get to P1, cycle through all standard settings till nothing is flashing, then hold up+Down. To get C1, cycle through all [P] settings till nothing flashes and hold up+down. To exit and save at any point hold power.) I am not sure if C settings can be saved through the display, and as with all Use at own risk!
http://www.szktdz.com/upload/file/20140913/20140913155038_92748.pdf
EDIT: Yep C settings can be saved, C7 enables Cruise control, so awesome

 

[docnjoj]

I found a detailed KT-LCD3 manual explaining all the Extra programming codes (P1-P5 & C1-C12)
(Enter standard programming by turning on and within 5 seconds hold Up+Down. To get to P1, cycle through all standard settings till nothing is flashing, then hold up+Down. To get C1, cycle through all [P] settings till nothing flashes and hold up+down. To exit and save at any point hold power.) I am not sure if C settings can be saved through the display, and as with all Use at own risk!
http://www.szktdz.com/upload/file/20140913/20140913155038_92748.pdf
EDIT: Yep C settings can be saved, C7 enables Cruise control, so awesome

I tried to save C8 which I believe allowed speedometer to read even when off the throttle, but it didn't change the speedometer going to 0mph when off the power.
otherDoc

 

[mountain biker]

man a lot of info on this motor...I appreciate it guys...its nice having a forum for a guy whos planning on a first build with such knowledgable guys.....I mean you could easily drop 2000 grand without your background knowledge just on a 250 watt motor with all the crazy info you get from sales adds online....

my concern then would be mounting this thing....experienced people on this forum or another forum told me to use disc brakes but what is the size of this disc brake motor.and cogs and I heard it is rather fat bigger than most....the add below from them says it is 132 mm...what does this mean? also on ebike.com I believe they said you need to use the vbrake mount on this bike because the width was too large....any info on this? and how do you find out how big your bikes fork width is if you don't have the bike yet...I am still shopping for bikes..sorry first build Walmart..probably mongoose line..but...

The main features of the two -speed motor:

a.small volume(max diametre is 132mm);

b.big torque,and climbing ability;

c.high effeciency(Big torque, low current );

d.when installed the gearshift systerm(freewheel),the speed will be twice as fast as the original speed.

Front motor :

 

[Alan B]

...
I tried to save C8 which I believe allowed speedometer to read even when off the throttle, but it didn't change the speedometer going to 0mph when off the power.
otherDoc

In order to get a speed reading when the motor is not powered (and hence not spinning) a separate speed sensor would be required.

 

[docnjoj]

...
I tried to save C8 which I believe allowed speedometer to read even when off the throttle, but it didn't change the speedometer going to 0mph when off the power.
otherDoc

In order to get a speed reading when the motor is not powered (and hence not spinning) a separate speed sensor would be required.

I kinda thought that and can try it easily as I have an unused one on the trike.
Thanks Alan
otherDoc

 

[menvert]

I tried to save C8 which I believe allowed speedometer to read even when off the throttle, but it didn't change the speedometer going to 0mph when off the power.
otherDoc

I am not sure what you mean doc? C8 says it's temperature display on that pdf? (I will post my defaults tonight if you like and see if any differ)
Either way I always get a speed reading, as long as the display is turned on, which makes sense because then the hall sensors would be active. This might be a Controller revision thing? I frequently compare rolling speed and FOT speed down hills to see how high it'll still speed me up (motor still pushes up to 38kph down hill for me)

I am getting used to this motor, but wish there were codes for adjusting gear change parameters, the auto is totally useless and the time to change gears means I rarely use Low, as starting in high is usually greater acceleration overall.
Cruise is nice too, but PAS does turn it off, meaning I can't cruise and pedal with PAS enabled, might need a switch for that.
Pulsing accelerator turns cruise off as do brakes and any buttons (inc. gear change). Cruise just holds accelerator voltage, it's not based on speed which is good.