Search found 2143 matches

by larsb
Jul 29 2021 11:06pm
Forum: Motor Technology
Topic: QS 3000w midmotor
Replies: 650
Views: 88970

Re: QS 3000w midmotor

rider119 wrote:
Jul 29 2021 2:01pm
Does anyone know the impedance of the QS120 70H and QS138 90H?
It’s about 5mohm for the 138 70H
by larsb
Jul 29 2021 9:14pm
Forum: Motor Technology
Topic: QS 3000w midmotor
Replies: 650
Views: 88970

Re: QS 3000w midmotor

I’ve run it at 80V 300A dc input, jbjork about the same.

The geared version won’t be different. (Off course depending on total gearing)
by larsb
Jul 21 2021 3:13pm
Forum: EScooters/EMotorcycles
Topic: QS 138 70H with Gearbox
Replies: 101
Views: 6099

Re: QS 138 70H with Gearbox

Yes, you’re correct, it’s based on the assumption of kV60 for the 70H, then assumption that kV is inversely proportional to stator length to 60*(70/90) which gives kv=47 for a 90H with same winding as the 70H. Then an assumption that both motors have the same copper fill which means that the possibl...
by larsb
Jul 21 2021 1:53pm
Forum: EScooters/EMotorcycles
Topic: QS 138 70H with Gearbox
Replies: 101
Views: 6099

Re: QS 138 70H with Gearbox

I can’t really be bothered to check it but i vaguely recall 16mm2 phase wires stated for the 70H and 20mm2 for the 90H. That would *ehrm* indicate a winding change where 60*70/90*(20/16) gives kV 58 for the 90H as compared to the 60kV for the 70H calculated with some basic assumptions behind. There ...
by larsb
Jul 21 2021 9:52am
Forum: EScooters/EMotorcycles
Topic: QS 138 70H with Gearbox
Replies: 101
Views: 6099

Re: QS 138 70H with Gearbox

Next thing i’ll ask is how relative torque vs inertia changes when a motor is made longer.. :mrgreen:

Does it change..really?
by larsb
Jul 21 2021 9:45am
Forum: EScooters/EMotorcycles
Topic: QS 138 70H with Gearbox
Replies: 101
Views: 6099

Re: QS 138 70H with Gearbox

Seem to understand? You did not understand: i said there was a change in the winding to keep the kV the same or it would have been roughly 60*70/90, so 47 for the 90H motor.

I just asked to prove you don’t know what you’re talking about. Give a man enough rope..
by larsb
Jul 20 2021 10:45am
Forum: Stand-up EScooter/ESkateboards
Topic: Speedway 5 cutting out under acceleration
Replies: 1
Views: 210

Re: Speedway 5 cutting out under acceleration

Third time it did it was this week - at 78% charged. I was watching the display screen at the time, and the voltage under acceleration dropped by just 2 volts (from around 52 to 50, nowhere near the 44V cutout I think the scooter has built in to the BMS). As it cut, the display flashed, and the vol...
by larsb
Jul 10 2021 7:15am
Forum: Motor Technology
Topic: Winding Question: does STAR make more torque than DELTA, even with adjusted phase current?
Replies: 47
Views: 3448

Re: Winding Question: does STAR make more torque than DELTA, even with adjusted phase current?

Yes, this is really interesting. Difference in inductance might between delta/star might be hard for the nucular to handle?
by larsb
Jul 07 2021 1:35pm
Forum: Motor Technology
Topic: Motor theory? Size/rpm, wattage.
Replies: 14
Views: 500

Re: Motor theory? Size/rpm, wattage.

i would rather say that efficiency is the limiting factor. It's popular here to use a small motor, overdrive it and focus on cooling. "Hey, this small motor will produce 2kW!" when actually it barely can take 2kW input at a terrible efficiency. A motor has it's sweet spot for use, no point...
by larsb
Jul 06 2021 5:12am
Forum: EScooters/EMotorcycles
Topic: QS 138 70H with Gearbox
Replies: 101
Views: 6099

Re: QS 138 70H with Gearbox

0AEAACC4-50D0-4C7E-BA17-398358BEAD0F.jpeg Here we go from 90H vs 70H and then the magnet question. Since we’re discussing a really similar motor with increased length it’s not complex. there’s no point to compare two motors with different diameters or such difference and ask what is the best magnet...
by larsb
Jul 06 2021 3:29am
Forum: EScooters/EMotorcycles
Topic: QS 138 70H with Gearbox
Replies: 101
Views: 6099

Re: QS 138 70H with Gearbox

There is an optimum magnet width for the stator width so normally it would not be just the magnets that are longer.

With a longer magnet and stator (all else being the same) you get more field/force/torque produced per current so kV will be lower if the winding isn’t changed.
by larsb
Jul 06 2021 12:19am
Forum: EScooters/EMotorcycles
Topic: QS 138 70H with Gearbox
Replies: 101
Views: 6099

Re: QS 138 70H with Gearbox

As I said, there is so much more that influence motor performance... but still with qs138 90H and 70H, with everything else staying the same, the first have more torque and turns a little slower than the smaller one. So you just stated the obvious and nothing more than what already said, but being ...
by larsb
Jul 05 2021 4:06pm
Forum: EScooters/EMotorcycles
Topic: QS 138 70H with Gearbox
Replies: 101
Views: 6099

Re: QS 138 70H with Gearbox

OK how about "better" for long steep hills & heavy loads at low speeds. Very slow top speeds. Yes, exactly. It sure depends mostly on what use you want to make of it. More mass means slower to overheat in that context? I think you can say so, probably not much of a problem in most use...
by larsb
Jul 03 2021 8:41am
Forum: EBike Technical
Topic: Potting windings on a hub motor
Replies: 21
Views: 614

Re: Potting windings on a hub motor

Mystery solved then! Might help others if you link the motor you’ve got. Could be advised to buy something else for the hotrodders.
by larsb
Jul 03 2021 4:36am
Forum: Motor Technology
Topic: Motor theory? Size/rpm, wattage.
Replies: 14
Views: 500

Re: Motor theory? Size/rpm, wattage.

Sure there are ratings, just that the small sized motor manufacturers don’t rate.

The reduction for a 50krpm motor that you need to drive at 50krpm to get that 40kW .. lets say 150kph 1.8m circumference wheel is 1390rpm and roughly a 1:36 gearing. Hard to do without adding a lot of weight and size.
by larsb
Jul 03 2021 2:35am
Forum: Motor Technology
Topic: QS 3000w midmotor
Replies: 650
Views: 88970

Re: QS 3000w midmotor

J Bjork just did a noload measurement on his QS 138 70h / (nucular controller) It's interesting to see the losses take a leap at 7500 rpm which i've seen QS state is the max rpm for this motor. QS 138 70H noload losses.JPG Could be an effect of the controller field weakening function not the best at...
by larsb
Jul 03 2021 1:15am
Forum: EScooter/EMotorcycle Build Threads
Topic: KTM 200 exc goes electric
Replies: 234
Views: 41625

Re: KTM 200 exc goes electric

Nice! :bigthumb: I’ve thought about doing the same measurements for a long time. So 1650w in average for 8500rpm, to get a reasonable 85% efficiency accounting just the noload losses one needs to use 11kW at this rpm. At 3kW riding power the efficiency at 8500rpm with just noload losses is down to 6...
by larsb
Jul 02 2021 9:42am
Forum: Motor Technology
Topic: Motor theory? Size/rpm, wattage.
Replies: 14
Views: 500

Re: Motor theory? Size/rpm, wattage.

For RC motors it's a special case where many of them are speced on the peak input power for a second or two. The load is normally a propeller so for a 40kW input to the motor for a second of super high RPM drive (50 000 rpm in this LMT30100 case) when you have 40kW of aircooling available. Put the s...
by larsb
Jul 02 2021 5:53am
Forum: EScooters/EMotorcycles
Topic: E-Motorcycle build advise
Replies: 15
Views: 472

Re: E-Motorcycle build advise

When you look at ant bms you could just go with this one instead: https://www.aliexpress.com/item/32826469363.html?spm=a2g0o.store_pc_groupList.8148356.1.44611d15WNwni1 Oh thanks! that looks perfect! I somehow never found that one in my searches, thanks for pointing it out. Running motorway speeds ...
by larsb
Jul 02 2021 4:45am
Forum: General Discussion
Topic: Is this the same KnightMB that sold us out?
Replies: 190
Views: 41245

Re: Is this the same KnightMB that sold us out?

I don't think a change of the name be good though, reasons given don't seem to warrant it enough in my opinion, I know the name originally given to a tech company but ES :es: seems to cross over perfectly for an EV forum, I think would be hard to find a better one, maybe in the spirit of community ...
by larsb
Jul 01 2021 3:36pm
Forum: EBike Technical
Topic: Potting windings on a hub motor
Replies: 21
Views: 614

Re: Potting windings on a hub motor

Yes, but according to spec sheets and wikipedia for winding wire the rating is max continous temperature. Peak temperature would be higher. You’re right, i had to check, 20000 hours at the rated temp should be enough. Then it’s pretty clear the chinese wire isn’t up to the said spec, or temp sensin...
by larsb
Jul 01 2021 12:29am
Forum: EBike Technical
Topic: Potting windings on a hub motor
Replies: 21
Views: 614

Re: Potting windings on a hub motor

Just saying.. see that “max winding temperature” per class?
ECDB7A33-9C56-4800-A735-03A0E60E1AC7.jpeg
ECDB7A33-9C56-4800-A735-03A0E60E1AC7.jpeg (94.69 KiB) Viewed 204 times
by larsb
Jun 30 2021 10:59am
Forum: EBike Technical
Topic: Potting windings on a hub motor
Replies: 21
Views: 614

Re: Potting windings on a hub motor

I think motors shouldn’t be run that hot, it’s wasting energy that could be better used. Might work, might not.

If you find a spec sheet saying the wire is 180deg continuous then please link it..
by larsb
Jun 30 2021 12:58am
Forum: EBike Technical
Topic: Potting windings on a hub motor
Replies: 21
Views: 614

Re: Potting windings on a hub motor

:wink: Lowering the temp would be a solution of course, but with this motor I was also testing how far I could go and I was worried more about the magnets which are rated 120 Celsius. Kv did not increase at all. Hall sensor are rated 150 degrees (no problems) and winding wire has a 180 degrees ratin...
by larsb
Jun 30 2021 12:48am
Forum: EBike Technical
Topic: Potting windings on a hub motor
Replies: 21
Views: 614

Re: Potting windings on a hub motor

Brocotts.co.uk
Wires.co.uk

But the damned brexit almost stops ordering from the uk, i waited 2 months for my last order.