Kingsong S20/S22 (Confirmed)

[bracky72]

Not sure if I’ve seen this mentioned. 127 volts can kill you way easier then 100 volt.  Maybe that could be their new slogan. King Song - Ride the Lightning.

[PourUC]

30 minutes ago, Planemo said:

I get that more voltage = less current requirement but are there really that many 'normal' riders who are burning their wheels up?

I don't believe the S20 is marketed towards 'normal' riders.

They are not discontinuing their S18, this isn't a replacement in their lineup, it's a higher end wheel for people that want it.

[PourUC]

9 minutes ago, bracky72 said:

Not sure if I’ve seen this mentioned. 127 volts can kill you way easier then 100 volt.  Maybe that could be their new slogan. King Song - Ride the Lightning.

As long as the board is made properly this shouldn't be an issue.

The only way the 127v could realistically reach you is if you fall off lets say, the circuit is somehow intact but all the shielding is removed and you also take the cover off with bare hands/low insulating gloves and get too close to their high voltage circuit.

100v can kill you way easier than 67v. I find people's arguments here to be very flawed. Either embrace it or seek out the lowest possible voltage for the speed you want to ride at.

For reference, in the UK we have 230v running through our houses into basically every appliance. Inside the appliance is often a power supply that steps the voltage down to whatever the appliance needs. That is a high voltage circuit, yet people are not dying because they plugged their phone in to charge and the charging brick failed and zapped them to death.

Edited September 12, 2021 by PourUC
addition of anecdote

[bracky72]

A tire change for example will have you working inside the unit around high voltage lines.  Does the average Person go digging around inside the junction box?  I’m just pointing out a consideration. I am comfortable with it.

[Rawnei]

3 hours ago, mike_bike_kite said:

I'll admit I can't see the point of having over 100v either. My Nik+ goes fast enough to get me in trouble. I know there are a few individuals who want to go at silly speeds but the majority of us probably stick to more sensible speeds. I think Seba did a study of the data fed into EUC world and 90% of riders rode 15mph-25mph (I can't recall the exact numbers). I appreciate you guys have already designed the wheel, and it looks great, but I can't see the point of the big voltage jump. Could anyone say the pro's and cons of doing this? 

The way I see it is that they've designed a wheel that will fit a majority of riders, no matter if you wanna go fast, slow, off-road, pavement, skatepark, etc. It has it all, great all-around potential if it lives up to all those specs.

[Planemo]

51 minutes ago, PourUC said:

The amperage going into the board would still be high.

I get that

51 minutes ago, PourUC said:

We went from 67v to 84v to 100v all for the same reason essentially.

This is where I am not so sure. The big push to 100v was purely for speed reasons IMO. I am not sure that GW were too worried about the odd 84v MSX board burning up due to current. But you may feel different of course.

51 minutes ago, PourUC said:

Your argument could be given to 100v wheels, why not stay at 84v and just put more batteries in parralel so that higher amperages can be achieved.

Haha, touche

I do take that point as well. But lets just say that at around 60v you are right at the edge of Speed Vs Torque (and safety) requirements for what many riders want, in conjunction with 'reasonable' board design/components (lets say Z10). So with 60v as a benchmark minimum, how much voltage is actually needed? I guess the question is, how much is enough? 84v raised the bar as you say, gave us more speed and reasonable current requirements. So then we went to 100v, even more speed and again less current. So now we are at 127v, at what point do we say 'shit lads, lets make some decent electronics because otherwise we are gonna need 240v soon'

51 minutes ago, PourUC said:

Because the components that amperage has to go through now needs to be much beefier than just increasing the voltage and insulating the board better.

Totally agree, but there will always be a voltage limit somewhere, so I think we are nearing the point where the manufacturers need to focus on building decent enough electronics to handle the current, rather than just continually upping voltage.

Anyway, apologies, I think I have de-railed it enough. I do take and accept just about all your points though.

[Eucnhtusiast]

2 hours ago, PourUC said:

It's not about raw speed. It's about current overhead. What causes cut out's is when the amperage requested to balance the wheel is greater than the batteries/controller can output.

By increasing voltage you lower current for the same overall power. This means you have more of a current overhead to prevent cutouts.

When jumping a wheel you can see really high current draw when you accellerate up a steep ramp and also when you land. It makes sense to go as high voltage as you can as long as you mitigate the risks that the voltage brings for electric motors.

On EUC world, the safety margin you see is current based. With a high voltage wheel + a conservative speed cap, we should expect basically no cases of overpowering the wheel unless you REALLY try.

This is a common misconception in the EUC community, power isn't a currency you can trade like this.

 

 

 

A motor with higher voltage uses roughly the same amount of current as a lower voltage motor if the load and the motors are similar. The voltage is there to push the current and to push against the back EMF from the motor. It won't magically use less current just because the power is the "same". Torque is directly affected by current and if the torque requirement is the same, both motors will use the same current. What the voltage does is increase rpm potential(and raise the ability to apply that torque across the rpm range so the "net torque" is higher but the max torque is exactly the same), so a lower speed motor can be used that has more torque thus using less current to maintain same torque output. The safety comes from the motor structure being more torque oriented, not because of the higher voltage. A higher voltage ENABLES you to increase 2 parameters, torque and speed. If you use the same motor, you get 25% more RPM out of that same motor but no torque increase. If you use a lower speed motor that has the same rpm as the og motor at a lower voltage the torque on the new motor got a 25% increase but no RPM increase. You can also do any combination of the two as a slightly lower speed motor could get more torque and more speed in the higher voltage system, but it wouldn't be as fast as the og motor or have as much torque as the much lower speed motor, it would have a mix of the two.

 

A sidenote, a higher voltage system could push more current through the same motor(motor resistance is a constant so a higher line voltage would result in more current), granting more torque, but that only applies if the controller and battery system can support it. Most EUC mobos burn at 25-40A continous so we will never see this in reality. 30A through the same motor at different voltages results in basically the amount same torque because the torque constant of the motor is the same and not affected by line voltage supplied through the motor

 

 

 

The safety margin on EUC World isn't based on current, but PWM signal. Do a lift speed, it'll draw a few amps, but the safety margin still goes down as the motor speed increases. 

[Chriull]

It's very easy  https://en.wikipedia.org/wiki/Motor_constants#Motor_torque_constant

If one looks at one specific motor with given materials, measures and magnets,... and one changes just the number of windings (and diameter of the wires) on directly changes the Kv constant - the voltage generated at a specific speed. So as written/discussed before this is one point on motor and battery voltage design - choosing the windings so the motor produces about (a bit less) as battery voltage at maximum speed (lift cut of speed).

As one can read in the above link there also exists the motor torque konstant Kt which equals torque divided by motor current. And this constant is the reciprocal value of the motor velocity constant Kv.

So if one has one motor design (measures, materials, magnets, ...) one gets the more torque per motor current as one gets less voltage per revolution. Or vice versa.

So if a specific motor is made for high low speed (low Kv) it will have a high Kt, meaning it creates more torque per current or other way round uses less current per torque.

So yes - increasing battery voltage is a very valid way to decrease motor current and by this the main mosfet burden!

Edited September 12, 2021 by Chriull
serious type - see next post

[Eucnhtusiast]

59 minutes ago, Chriull said:

It's very easy  https://en.wikipedia.org/wiki/Motor_constants#Motor_torque_constant

If one looks at one specific motor with given materials, measures and magnets,... and one changes just the number of windings (and diameter of the wires) on directly changes the Kv constant - the voltage generated at a specific speed. So as written/discussed before this is one point on motor and battery voltage design - choosing the windings so the motor produces about (a bit less) as battery voltage at maximum speed (lift cut of speed).

As one can read in the above link there also exists the motor torque konstant Kt which equals torque divided by motor current. And this constant is the reciprocal value of the motor velocity constant Kv.

So if one has one motor design (measures, materials, magnets, ...) one gets the more torque per motor current as one gets less voltage per revolution. Or vice versa.

So if a specific motor is made for high speed (low Kv) it will have a high Kt, meaning it creates more torque per current or other way round uses less current per torque.

So yes - increasing battery voltage is a very valid way to decrease motor current and by this the main mosfet burden!

A low Kv motor is slow speed high torque, not high speed high torque. Pick one, high torque or high speed, not both...

 

Kv and Kt are inversely proportional. Lots of turns of small wires(low kv, high kt) creates a slow motor that can harness the PM fields efficiently(ie has a lot of torque at low amperages). A few turns of thick wire(high kv, low kt) creates a fast motor that can't harness the PM fields as efficiently, but that lets it go much faster.

So a 100kv motor driven at 10V spins at 1000rpm at no load

A 1000kv motor driven at 10v spins at 10000rpm at no load.

 

"So if a specific motor is made for high speed (low Kv) it will have a high Kt, meaning it creates more torque per current or other way round uses less current per torque."

This is either a typo or you have understood this very wrong, which is it?

[Chriull]

7 minutes ago, Eucnhtusiast said:

Kv and Kt are inversely proportional.

As that is the main point of my post this 

 

1 hour ago, Chriull said:

So if a specific motor is made for high low speed (low Kv) it will have a high Kt, meaning it creates more torque per current or other way round uses less current per torque.

this was a typo that makes no sense in combination with the rest of the post, as you wrote.

Thanks for correcting it!

[Eucnhtusiast]

3 hours ago, Planemo said:

I'm not aware of a slew of people getting slow speed cut-outs because of burnt boards on Shermans (taking aside OH Hill and the looney riders trying to go up 45deg inclines), but I take your point.

The option of course is to simply build a better board.

I get that more voltage = less current requirement but are there really that many 'normal' riders who are burning their wheels up? Especially KS riders who aren't known for their riding lunacy.

I'm not knocking KS for doing this, I'm just not entirely sure it's necessary for any wheel, let alone one that isn't intended for speed. In short, if someone wanted a hugely powerful 30~35mph tops wheel, just wind a really high torque motor, strong board and 100v in 10P format. A bit like an RS HT but with an ever torquier motor wind, maybe an inch or so smaller wheel diameter and a 10P pack instead of 6P.

It's not like running 126v doesn't bring with it it's own problems anyway.

As I say, props to KS for at least venturing into this, but I have yet to see a well-explained reason why they did, given that IMO you could do it with 100v if you really wanted to. I do stand to be educated though

 

See this doesn't work, a high torque motor creates a LOT of back EMF, which rises with motor rpm(the motor is creating an opposing voltage that affects the ability of the battery to supply current). Once high enough, NO current can flow into the motor, thus no torque is produced meaning you fall. No amount of parallel batteries can solve this. Upping the voltage lets you do what you think parallelling more batteries does. Which is flowing current in to the motor to produce torque.

[Eucnhtusiast]

1 hour ago, Chriull said:

So yes - increasing battery voltage is a very valid way to decrease motor current and by this the main mosfet burden!

*Only if, you use a lower speed higher torque motor. Inherently the higher voltage doesn't reduce current use in any way.

Edited September 12, 2021 by Eucnhtusiast

[UniMe]

Lots of technical discussion, but for me the question is simple -- would a higher voltage motor allow me to use the S20 in aggressive off road conditions as a 235lbs rider?

I'm not really interested in going fast on pavement and have long believed that the real future for EUCs lies in suspension and more efficient/lighter batteries and more powerful motors. None of the existing wheels are really there yet and need to be 'babied' to not burn them out, blow up the suspension etc. I have a background in mountain biking and dual sport motorbikes, I'd like to be able to push a wheel off road has hard as my body will allow me and for the pinch point to not be the hardware/wheel.

It's my impression that the S20 is a step in the right direction in terms of my fantasy application so long as the higher voltage allows me to lean hard on steep off road inclines long enough to get over them. I don't need to drone up 'overheat hill', but I do want to be able to climb up to a set of trails, handle the ups and downs of our very inconsistent local terrain etc. Even better, to get away from the 'kiddie park' bike trails and to go out where the off road motorcycles play!!

So, to the very intelligent and technically savvy folks here -- does the S20 get me there?

[Eucnhtusiast]

5 minutes ago, UniMe said:

Lots of technical discussion, but for me the question is simple -- would a higher voltage motor allow me to use the S20 in aggressive off road conditions as a 235lbs rider?

I'm not really interested in going fast on pavement and have long believed that the real future for EUCs lies in suspension and more efficient/lighter batteries and more powerful motors. None of the existing wheels are really there yet and need to be 'babied' to not burn them out, blow up the suspension etc. I have a background in mountain biking and dual sport motorbikes, I'd like to be able to push a wheel off road has hard as my body will allow me and for the pinch point to not be the hardware/wheel.

It's my impression that the S20 is a step in the right direction in terms of my fantasy application so long as the higher voltage allows me to lean hard on steep off road inclines long enough to get over them. I don't need to drone up 'overheat hill', but I do want to be able to climb up to a set of trails, handle the ups and downs of our very inconsistent local terrain etc. Even better, to get away from the 'kiddie park' bike trails and to go out where the off road motorcycles play!!

So, to the very intelligent and technically savvy folks here -- does the S20 get me there?

It's all new and unproven technology at this stage, nobody can say yet. And once it releases, it probably won't compete with gas bikes, period. The RS is as good as it gets with torque, so the gw Hero would be more suitable for your use case, but I digress.

[Paul A]

Electric motorcycle, some specifications, might be relevant with regards to what is possible.

https://www.energicamotorusa.com/electric-motorcycle-energica-ego/

POWER: Peak 169 Hp – 147 Hp Sustained

TORQUE: 159 lb.-ft

TOP SPEED: 150 mph

ACCELERATION: 0-60 mph 2.6 sec

RANGE: 261 miles City / 123 miles Highway / 153 miles Combine

BATTERY CAPACITY: 21.5 kWh lithium-ion battery that is still largest of any bike

MOTOR: HSM (Hybrid Synchronous Motor) Liquid-Cooled 3-Phase – 300 V – 12,000 rpm with Adaptive Control Inverter

 

 

[Rollin-on-1]

1 hour ago, Paul A said:

Electric motorcycle, some specifications, might be relevant with regards to what is possible.

https://www.energicamotorusa.com/electric-motorcycle-energica-ego/

POWER: Peak 169 Hp – 147 Hp Sustained

TORQUE: 159 lb.-ft

TOP SPEED: 150 mph

ACCELERATION: 0-60 mph 2.6 sec

RANGE: 261 miles City / 123 miles Highway / 153 miles Combine

BATTERY CAPACITY: 21.5 kWh lithium-ion battery that is still largest of any bike

MOTOR: HSM (Hybrid Synchronous Motor) Liquid-Cooled 3-Phase – 300 V – 12,000 rpm with Adaptive Control Inverter

 

 

 

300 V – 12,000 rpm with Adaptive Control Inverter

Sounds like it could be an AC motor with talk of an inverter.

[Chriull]

5 hours ago, Eucnhtusiast said:

*Only if, you use a lower speed higher torque motor. Inherently the higher voltage doesn't reduce current use in any way.

Yes. But it gives the possibiliy if it is a design decision.

As Kingsong historicly was never on the top with high speed it is likely that the higher battery voltage is used for "low current torque" - relieving the burden from the mosfets. Or most likely some "nice" compromise by also getting a bit higher with speed, especially increasing the safety margin.

Hopefully the "open design" will be used to additionallly provide some real cooling for the mosfets. And place the capacitors so they stay well wirhin their 105°C limit. And, like inmotion used multiple paralleled smaller capacitors to divide the ripple current - as far as i understood this...

But as you wrote, we'll see once it's released.

[UniMe]

Ya, obviously I'm not comparing it to a gas dirt bike... 

If folks don't ride in off road terrain then you probably won't know what I mean. there's the flat, rolling off road that I see a lot of EUCs on, and then there is real off road that is not well groomed and has much less consistency in the terrain. Lots of steep ups and downs, short bursts of power to get over things etc.

The bar is obviously very low as we're just a couple years past EUCs being overbuilt toys. They have potential though... especially with adequate suspension travel and power. They're also relatively cheap... could have 2-3 for the cost of a dirt bike (well, the type I would buy anyway). so riding one with another charged up in the truck for a swap. Or, like Zero tried to implement (rather unsuccessfully), swapable batteries!

The other thing I would really like to see is a software feature that prevents the wheel from changing direction and spinning uncontrollably in reverse when airborne... even with little hops this is a risk. Small backward spin puts a lot of unnecessary strain on the wheel, uncontrolled = immediate faceplant. There must be a way to prevent this from happening, and the need to do it will become more and more important as the wheels develop robust suspension that begs to be jumped. don't know about you all, but I tend to lean back a small amount when in the air. It's instinctive at this point.

Edited September 12, 2021 by UniMe

[mrelwood]

16 hours ago, Eucnhtusiast said:

A low Kv motor is slow speed high torque, not high speed high torque. Pick one, high torque or high speed, not both...

There are more than two possible Kv ratings to aim for when making a motor.

 The way Jack@KS explained it was that they built (or plan to build) a 126V high torque motor, the high voltage making it also higher in speed than a 100V HT motor. So in a sense, they do plan to pick both.

15 hours ago, UniMe said:

would a higher voltage motor allow me to use the S20 in aggressive off road conditions as a 235lbs rider?

In itself not really. But if KS succeeds in what they are planning for the S20, it would allow you to use it more aggressively than some other wheels.

 If you check my YT videos on off-road riding, you’ll see I ride very gently since the V11 (and the MSX) doesn’t have the power for my weight to be aggressive in those situations.

7 hours ago, UniMe said:

The other thing I would really like to see is a software feature that prevents the wheel from changing direction and spinning uncontrollably in reverse when airborne...

I don’t think we are anywhere near the point that we could trust a jump sensor made by an EUC company, that would immediately throw us to the ground if the sensor activated when it shouldn’t. You know, would you trust a cheap Chinese throwing seat on a jet fighter?

7 hours ago, UniMe said:

I tend to lean back a small amount when in the air.

You actually might not after all. Since you lift the wheel up with your forefoot on the pads that are in front of the axle, the wheel will turn back during the jump no matter how straight you jump. This is something you can learn to compensate for though. It didn’t take long for me to learn to jump on flat ground without the motor spinning backwards. My jumps on flat ground were of course very short in duration, but I see no reason the technique couldn’t be used for longer jumps as well.

 Looking at the videos of the craziest jumpers in the world, Fantomas and the guy with zero protective gear from USA, they definitely must have the aerial positioning dialed in perfectly, since a rapidly backwards spinning tire at those speeds would most likely be an instant throw-off.

[Eucnhtusiast]

50 minutes ago, mrelwood said:

There are more than two possible Kv ratings to aim for when making a motor.

 

 The way Jack@KS explained it was that they built (or plan to build) a 126V high torque motor, the high voltage making it also higher in speed than a 100V HT motor. So in a sense, they do plan to pick both.

Yeah, you could do any number of combinations, factor in the magnets, stator poles and all that...

 

The pick one only applies when the operating parameters are the exact same(ie, line voltage, controller, etc), comparing a higher voltage system to a lower voltage system is redundant, the higher voltage system can apply more work in any situation regardless of motor specifications(well if the motor is smaller then this doesn't apply). This is like comparing an 3.0l inline 6 to a 4.0l v8 and saying the v8 is better because it has more pistons, while technically true, the added displacement is actually what matters more.

[mike_bike_kite]

1 hour ago, mrelwood said:

You know, would you trust a cheap Chinese throwing seat on a jet fighter?

I suspect Chinese pilots in the People's Liberation Army cross their fingers when they press any button in the cockpit. 

[Planemo]

20 hours ago, Eucnhtusiast said:

See this doesn't work, a high torque motor creates a LOT of back EMF, which rises with motor rpm(the motor is creating an opposing voltage that affects the ability of the battery to supply current). Once high enough, NO current can flow into the motor, thus no torque is produced meaning you fall. No amount of parallel batteries can solve this. Upping the voltage lets you do what you think parallelling more batteries does. Which is flowing current in to the motor to produce torque.

Thanks for that, I stand educated! Well explained

I'm still not sure we need 126v wheels though, most 100 volters seem to be doing pretty good these days. I do accept that raising the bar is always inevitable though 

[Paul A]

Ejecting from any fighter jet can be deadly.

One in three probability of breaking spine.

Acceleration forces can be up to 16G.

Downward forces on mass of head, helmet, mask can break the neck.

Leg fractures.

Can impact on overhead canopy that hasn't separated cleanly or quickly enough.

Possibly ejecting at high altitude into thin air, at supersonic speeds, into wreckage debris.

[ir_fuel]

Sounds like fun!

[RagingGrandpa]

18 hours ago, UniMe said:

there's the flat, rolling off road that I see a lot of EUCs on

"Onewheel trails"

18 hours ago, UniMe said:

and then there is real off road that is not well groomed and has much less consistency in the terrain. Lots of steep ups and downs, short bursts of power to get over things etc.

^ the domain of high-torque wheels

On 9/12/2021 at 12:03 PM, UniMe said:

235lbs rider

existing wheels need to be 'babied' to not burn them out, blow up the suspension etc.

I think the S20 won't meet your expectations for durability.

TBD if the motor will be powerful enough for your riding style (probably not), but this kind of aggressive riding means the EUC will tumble down hills, frequently and inevitably. S20 and its collection of exposed suspension linkages will be quickly damaged.
 

I think the best EUC we have for this type of terrain today is MSuper C38 + fiberglass bodyguard; and S20 is not going to improve upon it.

"Then what's the S20 for?"

It's got the torque of the 16X, the speed of the C30's, and the ride of the S18! Sounds excellent for aggressive paved-surface riding.

It'll do ok on trails too. Baby it or break it, your choice.

 

 

Edited September 13, 2021 by RagingGrandpa