Inside look at new 50h QSmotor V4 8000W 13" hub motor

MJSfoto1956

10 kW
Joined
Jul 28, 2010
Messages
960
Location
Boston, MA
Being the curious type, I thought I'd take a peak at what the insides of my new 50h QSmotor V4 8000W 13" hub motor looked like. Here's what I found. Enjoy!

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IMG_8523 (2).1280.jpg


Note: if there is something you want me to measure or photograph while this puppy is open, let me know.

Michael
 
how much was that bad boy and what's the dropout spacing and axle flats diameter.. would make a nice supermoto rear wheel for pit bikes:) ..
 
efMX Trials Electric Freeride said:
how much was that bad boy and what's the dropout spacing and axle flats diameter.. would make a nice supermoto rear wheel for pit bikes:) ..

  • 200mm dropout
  • 14mm axle flats
  • $737US shipped to Boston Massachusetts USA

Note: they also offer a (much more expensive) 70h 14000W 13" motor, but requires 230mm dropouts.
 
Honestly, the #1 reason I purchased the 8000W V4 over the 8000W V3 was for the bigger phase wires and the unique way they enter/exit the motor. None of that "through the axle" crap. I hope all hub motors going forward will be like this. And yes, I was willing to pay extra for that.
 
I'm sure it's a good motor, my question was rhethorical on how it can be competitive built like that. Long time since i read motor basics so i don't have any answers to this one.

If copper losses wasn't dominant at high power then i'd understand it.
 
larsb said:
All that extra copper length and resistance.
It's got distributed winding, how can it be worth it? In theory there's less harmonics and eddy losses, higher winding factor but it must be possible to improve a lot with a concentrated winding..

It does have concentrated wingings, maybe take a closer look. What you are seeing are the interconnects between each set on concentrated windings and the interconnects are obfusicating what is really going on with the winding pattern.
 
According to my QS salesman, the V4 motors are slower on takeoff but faster in top speed than the V3 motors (all other things being equal). Here is a chart I made from one of their few published comparisons of V3 vs. V4. Take it with a grain of salt please -- nothing scientific here at all.

Comparison of QS V3 vs. V4.1280.jpg
 
I like the lower pole count of this motor. It will make for less iron losses. And a small wheel will like it very much.
Indeed, you're gonna lose some torque from a stall, but you gain more later.

The way they've wound the motor is still crazy. Emphasis is on peak power, not efficiency. There's still a bit too much copper fill to make for tightly optimizing the windings to reduce end turn losses, etc.

I imagine that this is still a net improvement in efficiency versus the V3 tho.

Thanks for showing us ^_^
 
MJSfoto1956 said:
According to my QS salesman, the V4 motors are slower on takeoff but faster in top speed than the V3 motors (all other things being equal). Here is a chart I made from one of their few published comparisons of V3 vs. V4. Take it with a grain of salt please -- nothing scientific here at all.

I don't understand. Why do you post this? Is there a dyno plot? If so, then please post the original. This chart smells like a chinese sellers sales talk and doesn't help anyone if it's not corresponding to a real motor.

What would be the problem that needs to be solved by soft startup? And how do you get a faster motor with same kV?

It's not correct.
 
larsb said:
I don't understand. Why do you post this? Is there a dyno plot? If so, then please post the original. This chart smells like a chinese sellers sales talk and doesn't help anyone if it's not corresponding to a real motor.

What would be the problem that needs to be solved by soft startup? And how do you get a faster motor with same kV?

It's not correct.

Calm down dude. This is my interpretation of Chinese marketing. Nothing more. If you are looking for pure objectivity, you will be sorely disappointed (although my photos don’t lie). One should take everything from China with a “grain of salt” — do you understand what that idiom means?
 
flat tire said:
It's true. That plot is worthless.

Except that it is (well noted multiple times) as being anecdotal.
In spite of this, it has been verified by me in real world testing -- I have actually driven this motor, y'all have not.
So you calling me a liar now? :p

M
 
sn0wchyld said:
dimensions and weight? cant find the V4 on their site...

Really? One quick Google search and this shows up as the first link: https://www.qsmotor.com/product/13-inch-12kw-motor/

Note: the 12kW V4 motor has different dimensions than the 8kW V4 motor (which I have). Or put another way: the 8000W V4 motor has the same exact external dimensions as the 8000W V3 motor.
 
So the search doesn't actually show the correct motor?

And you felt the difference between v3 and v4 in your butt, it drew the diagram? Do you have the v3 on the same bike??

And how does the motor go 18% faster with same kV and all else the same?

"Here is a chart I made from one of their few published comparisons of V3 vs. V4"

And

"This is my interpretation of Chinese marketing"

It's nonsense. Why do you post it?
 
MJSfoto1956 said:
So you calling me a liar now? :p

If you're saying the chart is legit, maybe.

Really, I don't doubt you that on your setup you THINK the v4 has more top end and lower bottom end. But you should collect data. Human senses, memory, etc, are inferior to empirically measured stuff and wouldn't you know it, we have things called dynamometers (or, shunts and accelerometers) which make it trivial to put together USEFUL plots. Maybe the shape of those curves is real but then why would they put such stupidly useless axes? And at least SOME info on test conditions!

Finally, humans are notorious for mistakes and brain-error so you wouldn't need to be lying to think a bogus chart is legit and present it as such. You could just be misunderstanding, confused, mistaken, misremembering, etc.
 
larsb said:
So the search doesn't actually show the correct motor?

Oh Lars, Lars, Lars. Did you actually read the page? In detail? They mention different formats for the V4. Mine happens to be one of those. You can send them email inquiry if you feel so inclined. That is what I did, and I ended up buying one.

larsb said:
And how does the motor go 18% faster with same kV and all else the same?

Why not ask them, not me? I'm not advertising them. I'm just forwarding information that to date nobody else seems to have. Maybe it will help someone else? Maybe my butt is made of gold? Maybe you just like to troll people you disagree with? Who knows?

larsb said:
Why do you post it?

Um, because this is my thread. I get to post anything I want. If you don't like it start your own thread (perhaps entitled "QSmotor V4 -- do not buy!!!!"). Otherwise, you are starting to sound and act like a troll on my thread! :)

M
 
..so anyway, i'm apt to believe the claim of torque/efficiency curves changing with a change in the number of poles. It does make a difference in terms of eddy currents.

I imagine if there's any speed boost, it's from less magnetic drag at the higher RPMs mostly.

It would be nice if we had a dyno graph but it makes sense to me.
The marketing picture says 'similar kv', so that may make up a good % of the difference in speed ;)
 
Different kV would make it a different winding not really connected to v3 vs v4 difference. It would give a chart like that though.

I read mjsfoto drew the chart, it was done without any backing data. Fair enough but the format (to me) indicates some facts behind it.
 
So we can put this to bed, here is QSmotor's unscientific, fluffy, marketing page comparing V3 to V4. Honestly not much there, but it is what it is. It is from this page that I copied their diagram which I then "simplified" based on my own experience with the motor.

http://www.cnqsmotor.com/en/article_read_848.html

Michael

P.S. they also offer 17" rims in 70h V4 configuration
 
Now there's some meat on the bone. Seems like they do the same power within 20-50w on the dyno

V4 is measured 0.4% less efficient if the dyno plots are what they seem to be. I cannot get the foogle translate app working since my phone is too old now.. Maybe someone can beat me too it?
 
larsb said:
I read mjsfoto drew the chart, it was done without any backing data. Fair enough but the format (to me) indicates some facts behind it.

You think he's a shill for QS motor? :mrgreen:
Don't be so quick to assume..

Anyway, with the more detailed info, QS shows a tiny increase in efficiency.. i think they might have not dyno'd it to show the benefits, or while they made one positive change for scooter wheels, they went backwards in one area of the stator design.

They only spun it up to 1000rpm. In a 13 inch wheel, there is probably more of a difference due to the lower pole count, as you spin to 1500rpm and beyond.
 
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