QSMotor hub motors, low start torque?

So I've got almost 2 big electric conversions finished now. The first being a sport ATV conversion, using the new QSMotor 8000w mid drive paired with an APT 96800 controller. The 2nd one, which I'm finishing up, is a sit-down reverse trike for the road. It is using the big 12kw QS hub motor, along with an APT 96800 as well.

The electric ATV is a definitely a monster. The torque and acceleration if produces is very impressive. I can shred the back tires loose from a stand still, and do wheelies with ease. I'm sure it'd easily go up any off-road hill climb I'd point it at.

As for the reverse trike, my first tests so far are not along the same lines as the ATV. The reverse trike is about 130 pounds heavier than the ATV. Trike is around 580 pounds, which isn't a huge amount. That being said, the starting torque of it is very underwhelming. It is really mushy off the get-go, and in fact, if I was to have a passenger and tried to start on a steep inclined road, I think it would even struggle to get moving. I've tested it various times on my driveway, which is a steep paved surface. It is definitely far from impressive off the line going up it. After testing up hill from a stop several times, the phase wires do get fairly warm, and the motor is also warm (though less than the phase wires). I've also tested it on a steep backroad while moving, and was able to get up to around 50mph up the steep road, which is pretty good and would seem about right. Which leads me to believe everything is working on it's supposed to.

Still, my concern is the starting torque. I realize the trike is about 130 pounds heavier than the ATV, and the trike's hub motor is basically "geared" a bit higher as well. But should the starting torque really be that weak on these things? Like I said, from my few backroad tests so far, speed while moving seems fine, it's just that it doesn't feel very torquey, whereas the ATV motor most definitely does. Both use the same controller, and I don't believe there are any settings I missed, so I'm just a little confused here.

Can anyone testify on this? Do you have a QS hub motor? Is slow or strong from a stop, and/or could you do a wheelie or burn out (without holding the brake) if you really wanted?

-Thanks!

Just re-asking again after a month. The 12kw hub motor is still working great, and seems to perform best at higher speeds once it gets going. I'm still a little confused why the starting torque is so weak though. Can anyone attest for hub motors being like this?

I think hub motors have less starting tourqe due to their bigger rotating mass.
I have a 5kw hub motor in my scooter and the sabvoton svmc72150, starting acceleration is also lower than in the midrange, topspeed is also very good.
When I read from motocross bikes and see videos with the 4kw mid drive motor and the same controller, I also think there must be something wrong.

I think the controller has to limit the phase current to protect himself when the motor is near zero rpm.

Sounds like a controller setting...

I have measured the phase current with a rogowski current transducer and a scope meter. It takes a small amount of time until the controller reaches the maximum phase current and from there the phase current is the same until the controller reaches the maximum battery current. So from standing still with way under 1kw to 40kph with a maximun 13kw battery current is rising and motor power also. Zero rpm means also near zero volts at the motor, because dc-resistance is very low. The efficiency from the motor is also bad around zero rpm and raises fast with more rpm. Those mid drives make up to 7000rpm, the hub motor around 700-1500rpm.

To start faster the phase current has to be raised, to not overheat the motor in midrange the battery current should not be set to high. The 12kw motor can take around 25kw only for a short time.

by spinningmagnets » Aug 09 2021 1:14pm

Sounds like a controller setting...

Click to expand...

I added a ramp up to my settings as not to get full power for a second. With that said, some controllers have a delay set in the controller. I would check out the controller settings.

therobby3 said:

..., and the trike's hub motor is basically "geared" a bit higher as well...

Click to expand...

Geared higher means less tourqe.
How much higher?
What kV have you ordered and what size has your wheel/tire.

Ok thanks for the info. I'm not sure the KV on it, I'm assuming it's their "default" kv for the 12kw hub motors, since I didn't request anything special.

I've checked over settings and I'm not seeing anything I could be missing. The phase wires do heat up fairly quick when starting from a stop up the steep incline, so I'm thinking it's probably getting the amps it should. Just seems weird to me still, and I wasn't sure how other peoples hub motors performs.

I dont really have enough experience in big hubs or what difference to expect, but I cant say that I recognize the behavior.

I had an eeb with a qs 205 50h 4t and a nucular 24fet, and that would wheelie from a standing start if I didnt sit in front of the seat on the frame or stand and really hang over the handlebars.
(actually when I think about it it wheelies anyway, just not as much)

The bike was a lot lighter, me and bike was probably about 150kg.
And that was with 500phase Amps.

Maybe 800 just is not enough for that big motor?
You run the same controller on the middrive, you dont happen to have it set up for an IPM motor and get wrong timing on low rpm on the hub?

Ah, strange. I can definitely say mine doesn't put out the low end torque feeling like you are saying yours did. It is tough to say though, since mine is quite a bit heavier, although it's also a bigger motor/controller, so you'd think it may balance out a bit. The settings for the controller were pre-set my QS-Motor, I just increased a few setting but didn't play with any timing settings. So I would think they would have set it up correctly, but who knows. =/

Or they just entered the generic settings as a general guideline with zero fine tuning which is most likely the case without any prior knowledge, reading, web/ES searches, researching on what exactly QS does.

therobby3 said:

QS-Motor
So I would think they would have set it up correctly, but who knows. =/

Click to expand...

That is possible. I'll have to mess with some settings and see if I can get anything to feel a bit better. I'll probably just be taking shots in the dark, but we'll see.

therobby3 said:

I would think they would have set it up correctly, but who knows. =/

Click to expand...

I've bought directly from QS before, and grand total it was a good experience, but you can not assume that everything was all set up and ready to go.

My hub motor came out of the box running in with no current limiter and the phase angle set double what it was supposed to be. Turned out it was all setup problems in the controller that I was promised was pre configured for my motor and current requirements.

@millhouse Ah, perhaps I will have to ask around and see what everyone else set theirs at.

So unfortunately I had two wrong wires on my APT96800 controller touch each other and break something... So I had to get another and I got a 961000. Both were supposed to be preconfigured by QS Motor, but the 961000 was from their subsidiary or whatever called SiAECOSYS. I noticed that both of them had some parameters different from each other, even though they were set up for the same motor. The new one however, does seem to run a little better and have a little more torque, although that's partially to be expected seeing that it is a slightly more powerful controller.

But I'm asking, if anyone else has an APT 96v controller and a 12kw (or 8kw) hub motor, would you mind sharing any parameters or recommendations on what could use changed to get the most performance out of them? I did my first real range test last like and got around 150wh per mile which I'm a little disappointed with. I'm hoping I could change some controls and perhaps improve that.

I have some disappointing data in my apt96600 controller thread. The apt controllers from QS have been locked in different ways and they were not preconfigured in some cases so the issue is not a hub vs mid drive issue. A correctly controlled motor will put out enough torque.

The question might be what you compare also. A lightweight mid drive build with high gear ratio vs a hub with large wheel and a lot of weight is not a fair comparison. Just do the maths on max torque for the motors vs gearing to see what’s reasonable.

Yea, I've had 3 controllers from them now and they are all frustratingly locked in different ways on completely different settings. There's like no pattern to what the lock, it makes no sense.

It may very well be that it just doesn't feel as torquey because it is "geared" higher with the bug motor, yea. I just wasn't sure, as I thought it'd still feel a little more torquey from a stop.

I have ridden a bunch of QS hubs.. at least four different ones. Two were pooches, and two were rip oyour thumbs off style....

The pooches off the line was a 3T QS273 in a 19" rim, and a QS205 3T... on 72v. Using store bought packs... A big BTR battery and teh like...

.....teh " rip your thumbs off bikes" were a 6T, 205, and a 4T, 205 hub motor, on 72v with 3-5X the design amperage's on Chevy Volt lipos. In a 19" and a 17". Respectively. 107A on a "20A max" motor, and 280A on a "100a max" motor. Peaks.

Stuff it wth amps and a battery that wont.. comply. Junk batteries will comply, sag and heat up. A chevy volt lipo will push over 1000A if you let it... A Tessla 21700 can push like what.. 40A?

My 100A bike, has a battery that can push 10x the 100A.. easily.

Can someone say the same for (the) Tesla 21700 group? Lets say you have 10p.. 400A... Only 400A... For the same 100A bike..

You use 1/4 of the amps, available, I use 1/10..... of the amps.

Increase power supply wattage until you see "gains".. Then come back. 400A battery can only do 400A... but if you compare the setup to a 1000A battery.. You will win. 1000A battery will laugh at... 400A. Then you will smile for days. So ytou have a 12kW hub and 12kW controller.. but do you have a 12kW battery? No mention of batery.

Tork is all about amps off the line. Amps amps amps. A good power density helps with teh " off the line" part here..

"Starting tr active effort".. is whaty it is called... There are three types of " tractive effort" and they all intertwine..." Starting, Max, and contin.... Here you say you have good contin tractive effort, bike rides will at speed, where the least power is needed... , but bad starting ( and max, inherently) effort.. This can be fixed with more power, or a lower gearing ratio if you have the RPM reached of the RPMfinal).

Some of us are throttle happy, some of us are not. I know if a bike does not give enough umph on the throttle like I enjoy, I will not be happy.

I am a throttle happy junkie, for sure. But even with 8kW peak and 100A, my 100A bike, I can stall it in ta dead locked position (rotor locked stall current)... like if I place against a wall and sit on the bike and give a full throttle.

Yea, I believe my battery is fine. I use the same battery on my other build with the mid drive. So I don't believe the battery to be an issue. It uses Tesla 21700 cells with 26 in series and 17 in parallel.

442 cell pack.. 17p... Voltage of 109.2v charged. Nice.

Does it get hot under max current demand? What is the actual unloaded RPM of the setup?

....hell yeah I can do a wheelie with my lil QS hubbie. Lol. Burnouts in grass, mud, stones, up hills, yeah. I could litterally turn mu back yard to mud in one pack never going over 10mph but spinning at 40.... In one pack. Its even a big yard.

Brake on, feathered leaning nto the front fork? Will sit there and roll you at 3mph on pavement while the wheel sits at 45mph... If you can keep your balance. Its happy to. 8.4kV motor on 72vNOM and 84v Charged. Off the line or riding up to 20 mph. 19" rim. Lol. 3.3kW controller with a 100a peak. Under full sag up a hill I still reach 85% of my flat road performance max speed. Flat out. A little slower up the hill but not much.

I mean it. Almost ripped my leg off once ( I got pics) right off the line hitting full throttle from 2mph.... Went up like a rocketbike and threw me off and tossed itself 30 feet. Hospital and everything.. rashed it ( the bike and me) all up... I stayed on that wheelie for like.. 3 ? seconds before it tossed me into the ground and went upon its way end over end, bouncing and scraping...

I aint the only one. Ive seen others bikes that are like that.


IDKY you cant with that 21700 pack and 96v 200A controller.