Kingsong overheat tiltback : an added safety or a design flaw?

[Jason McNeil]

Nice, at least you've pinned it down to overheating. Are you doing a lot of braking? Where did you buy your Wheel from?

[Cloud]

@Jason McNeil yes, this only happens when i ride "aggresively"  on sidewalk with lots of accelerating and lots of braking at ever sidewalk ramp and behind people, than accelerating again. It only takes 5 minutes before it overheats. This kinda pisses me off because this is the riding style i like. 

Ive noticed that yhe temperature reading in the app seems to have a bit of a lag, which is to be expected i guess. So the temperature is probably higher than it shows and then the temp sensor "cathes up " with it and transmitts to the app. It is my impression that the overheating tilt back is set at approx 70 degrees celcius but the app shows precicely 68.8 when it starts happening as it has not caught up with the real temperature.

i also noticed another interesting thing. When i am just standing on a wheel and holding on to something, if i am standing still even on a very slight slope, the wheel of course is keeping me balanced but this must be putting a load on the motor as i watch the temperature rising. It was rising at a rate of about a tenth of a degree every 5 seconds or so and soon, once it reached 68.8 i had the tiltback while just standing in one spot

i bought the wheel from Tina but i dont think this particular wheel is defective. I think that kingsong needs to do a better job dissipating the heat. Also, the reason that others are not having these tiltbacks is because of my riding style. I ride dangerously and i expect that most people will shy away from this kind of riding style. 

It would be great though, if someone else tried accelerating and braking riding to see if they achieve the same effect

[sylvere]

Hope some wheelers can drive the same way you do see if they can reproduce it, we will received some 800W on the French market next week and we need do a lot of tests before introducing the wheels to the clients. We will try reproduce the same way you drive and see if this an happen to us.

Good luck 

[Cloud]

Hope some wheelers can drive the same way you do see if they can reproduce it, we will received some 800W on the French market next week and we need do a lot of tests before introducing the wheels to the clients. We will try reproduce the same way you drive and see if this an happen to us.

Good luck 

than would be great if you could confirm. The weight of the rider has to have an effect too. I am 100kg, i imagine that for a lighter person it would be more difficult to achieve the same effect. Also, the rider needs to be comfortable enough with the wheel to do what im doing with enough confidence and reasonably safe. 

Another way is to try standing still on a sloped surface while holding on to something for a few minutes and see if the temperature is rising and you can get the tiltback.

thanks 

[Cloud]

I just wanted to add something. Even though it seems like other have not experienced the overheating tiltback i believe its still an issue because it really is easy for the wheel to overheat. Not many people have kingsong yet so this data is still unavailable. You may think that this happens be ause of the "crazy " riding style i have, but its not so crazy. Basically i started having these a week or 2 weeks after getting the wheel and i wasnt as confident riding it then. I always like the speed but i wasnt trying to ride aggressively. Basically if you just ride at a high speed over sidewalks, you will be forced to accelerate and decellerate at every sidewalk ramp and around people. You dont have to act too crazy to raise the wheel temperature. 

What bothers me is that the temperature raises even when i am standing still on a slope. Basically you can turn on the wheel, stand in one spot for a few minutes and get the tiltback without even moving by a foot. My 100kg are heavier than most people but its not outrageously heavy and the wheel should be able to handle it. 

This is something Kingsong should definitely look into and work on. Unless my particular wheel is defective but it does not seem that way to me. I will be waiting for others to confirm my findings and / or for kingsong to listen and address.

[Donafello]

I just wanted to add something. Even though it seems like other have not experienced the overheating tiltback i believe its still an issue because it really is easy for the wheel to overheat. Not many people have kingsong yet so this data is still unavailable. You may think that this happens be ause of the "crazy " riding style i have, but its not so crazy. Basically i started having these a week or 2 weeks after getting the wheel and i wasnt as confident riding it then. I always like the speed but i wasnt trying to ride aggressively. Basically if you just ride at a high speed over sidewalks, you will be forced to accelerate and decellerate at every sidewalk ramp and around people. You dont have to act too crazy to raise the wheel temperature. 

What bothers me is that the temperature raises even when i am standing still on a slope. Basically you can turn on the wheel, stand in one spot for a few minutes and get the tiltback without even moving by a foot. My 100kg are heavier than most people but its not outrageously heavy and the wheel should be able to handle it. 

This is something Kingsong should definitely look into and work on. Unless my particular wheel is defective but it does not seem that way to me. I will be waiting for others to confirm my findings and / or for kingsong to listen and address.

I really curios to see if this is just your unit or across the board.  I'm very close in buying a second wheel and I loved the look of the kingsong 18, but with riding a msuper and never having any issues even while running it hard for 15 straight miles, this is concerning.  I am also almost 200lbs and live 10 minutes from cloud and ride on the same streets he does, and also run the machine pretty hard, so I'm sure if it's a issue with all units I would as well suffer from it.  I'm thinking of meeting up with cloud and trying his unit.  I'm about 25-30lbs less and we can see of that makes a difference.  I'm curious to see how this plays out before making a purchase. 

[OliverH]

This overheating happened also on a KS18 500W after a slow downhill track through the Forrest. I liked this feature. It's showing that you reach a threshold. My IPS T350 beeps and if you wait some time and go ahead the motor suddenly blocks. That's why I prefer a system stopping the user.

[zlymex]

I believe that KS's main-board is not efficient as other's, it just produce more heat than other EUCs at similar situation. .

IPS 122 vs MSuper2:
There is a hill in my city which we've climb it many times. There is no problem at all for IPS 122 what so ever even for a guy of 90kg. For MSuper2, we can just make the climb and start overheat till-back, temperature once went up to 84C. In this respect, IPS 122 is more efficient than MSuper. I also tested that IPS 122 needs 7.6Wh per km while Gotway needs 9.0Wh per km at typical riding situation. Someone said it's duo to the 12 MOSFETs that IPS employed instead of 6 in most of other EUCs.

MSuper2 vs KS 18":
The KS 18" owner start climbing another hill together with us at the same time but stopped midway because of overheat. He is about the same weight as us(<75kg). We(including 4 MSuper2) went to the hill top and wait him for 20min. to cool down. Another 110kg guy riding his MSuper2 also stopped at the same spot as can be seen on the 2nd photo which was taken by a long-focus-lens camera and still the white KS 18" barely seen.

Later, the KS 18" owner made an external heat-sink. Another KS 18" owner made some vents on the upper cover.
It's obvious that KS and Gotway shared the same origin and many people inside EUC circle know the story.

 

 

 

 

[Cranium]

What bothers me is that the temperature raises even when i am standing still on a slope. Basically you can turn on the wheel, stand in one spot for a few minutes and get the tiltback without even moving by a foot. My 100kg are heavier than most people but its not outrageously heavy and the wheel should be able to handle it. 

We can calculate how much power it takes just to hold you in place.  It is a simple calculation of weight (kg) * gravity (constant) * sin(angle of hill).

We will make the following assumptions:

1. The hill is 20°
2. Resistance of the wheel on the surface is negligible
3. The King Song is 90% efficient
4. Your weight is actually 100kg 

This would equate to (100kg+14kg) * 9.8m/s² * sin(20) /.9 = 425 newtons or 425 Watts.  

With this, it is easy to see why the temperature would be rising.  And when you aren't moving, there is no air flow which helps with the dissipation of heat so it will build up faster and keep rising.

[esaj]

We can calculate how much power it takes just to hold you in place.  It is a simple calculation of weight (kg) * gravity (constant) * sin(angle of hill).

We will make the following assumptions:

1. The hill is 20°
2. Resistance of the wheel on the surface is negligible
3. The King Song is 90% efficient
4. Your weight is actually 100kg 

This would equate to (100kg+14kg) * 9.8m/s² * sin(20) /.9 = 425 newtons or 425 Watts.  

With this, it is easy to see why the temperature would be rising.  And when you aren't moving, there is no air flow which helps with the dissipation of heat so it will build up faster and keep rising.

I've always thought that it also needs the speed (weight (kg) * gravity (constant) * sin(angle of hill) * speed (m/s)). So wouldn't that actually calculate the minimum amount of power needed (without air- or rolling resistance) when moving at 1 m/s (= 3.6km/h)?

[Cloud]

We can calculate how much power it takes just to hold you in place.  It is a simple calculation of weight (kg) * gravity (constant) * sin(angle of hill).

We will make the following assumptions:

1. The hill is 20°
2. Resistance of the wheel on the surface is negligible
3. The King Song is 90% efficient
4. Your weight is actually 100kg 

This would equate to (100kg+14kg) * 9.8m/s² * sin(20) /.9 = 425 newtons or 425 Watts.  

With this, it is easy to see why the temperature would be rising.  And when you aren't moving, there is no air flow which helps with the dissipation of heat so it will build up faster and keep rising.

this sucks. So i understand that both kingsong (14 inch as well as 18) and gotway are overheating faster than other brands. I understand the reason most people dont get overheating is their riding style. Most of my overheating happens not on a hill. My kingsong seems to be taking the hills ok, unless its very steep and then yes it overheats. But normally overheating occurs when you rapidly accelerate and then brake, accelerate and brake. If i try to ride fast on a sidewalk with pedestrians, this is why you have to ride and it sure overheats within a few minutes. I wish kingsong fixed it in their next models

[esaj]

this sucks. So i understand that both kingsong (14 inch as well as 18) and gotway are overheating faster than other brands. I understand the reason most people dont get overheating is their riding style. Most of my overheating happens not on a hill. My kingsong seems to be taking the hills ok, unless its very steep and then yes it overheats. But normally overheating occurs when you rapidly accelerate and then brake, accelerate and brake. If i try to ride fast on a sidewalk with pedestrians, this is why you have to ride and it sure overheats within a few minutes. I wish kingsong fixed it in their next models

There's current passing through the mosfets in both occasions (acceleration and braking), just the direction will be different (from batteries, to batteries), so it builds up heat either way, the more power drawn from batteries (or generated by braking), the faster and higher it heats up. Hopefully they'll add better cooling for the mosfets. Don't know if it was overheating or just a high current spike, but something sure blew up vee's mosfets really good a while back (on a Gotway MSuper):

 

 

[Cranium]

I've always thought that it also needs the speed (weight (kg) * gravity (constant) * sin(angle of hill) * speed (m/s)). So wouldn't that actually calculate the minimum amount of power needed (without air- or rolling resistance) when moving at 1 m/s (= 3.6km/

If you want to take into account the power needed to move up the hill, you need to also know the force needed to get moving and the force keep you moving (these are different).  These are also known as the static and kinetic coefficients of friction and will vary based on the surface you are riding on and the tire.  You would basically multiply this coefficient by the speed and multiply it by the power needed to stand still then add it back to the power needed to stand still.  Technically you would also need to take into account wind resistance but at 3.6km/hr, we will assume this to be negligible for simplicities sake.

So if we assumed the coefficient to be .25 (totally making this up) then we would have 425W * .25 * 1m/s + 425W = 531W to move forward up a 20° slope at 3.6km/hr.

[esaj]

If you want to take into account the power needed to move up the hill, you need to also know the force needed to get moving and the force keep you moving (these are different).  These are also known as the static and kinetic coefficients of friction and will vary based on the surface you are riding on and the tire.  You would basically multiply this coefficient by the speed and multiply it by the power needed to stand still then add it back to the power needed to stand still.  Technically you would also need to take into account wind resistance but at 3.6km/hr, we will assume this to be negligible for simplicities sake.

So if we assumed the coefficient to be .25 (totally making this up) then we would have 425W * .25 * 1m/s + 425W = 531W to move forward up a 20° slope at 3.6km/hr.

http://forum.electricunicycle.org/topic/478-brands-with-without-unexpected-shutdowns-new-buyers-look-here/?do=findComment&comment=5732

Plugging in the values of m = 90kg and 10 degree slope, we get:

90kg * 9,80665m/s2 * sin(10 degrees) = 153,2616... N

1 Newton (N) = 1 (kg * m) / s2

Now we add the speed, 10km/h, which needs to be changed to basic units (meters per second), to get the watts (W, power), 1 watt = 1 J/s, 1 J = joule = 1 N*m (newton meters), so

N*m/s  =  J/s = W (watt)

Back in the day, my physics teacher always said that if you suspect the equation to be wrong, inspect that you get correct units out of it  

Edit: so to clarify: the point was that your original equation states that:

This would equate to (100kg+14kg) * 9.8m/s² * sin(20) /.9 = 425 newtons or 425 Watts.  

But you only get 425 WATTS out of it, if moving at 1m/s (because otherwise the result is newtons, which is different than watts).

</nitpicking>

[Jason McNeil]

Comparatively, I don't think the King Song has more heat dissipation issues than other brands. There are probably three issues at play: 1) the IPS control-board has a block of aluminum which has twice the mass of the KS, 2) because the peak power in the KS is so much higher (at least 2x more than current IPS's) riders will be pushing their KS harder than most other brands, 3) heat has a tendency rise, the control-board is located in a small enclosed space at the top of the Wheel—even though it's exposed through the Wheel housing, heat transfer of air is not very efficient.  

King Song are well aware of the susceptibility to overheating if pushed hard, but there's no easy fix for the moment:

1. Internal fan without ventilation won't do very much
2. Inserting ventilation creates water ingress problems
3. Larger heat-sink has marginal benefit
4. Heat-sink fins (on the tire side) might be effective, but the current design of the shell doesn't have space for this
5. A heat transfer plate to an inner-lining of the wheel housing could help but binding two pieces of metal together, while still making it serviceable is tricky

 

[OliverH]

Which Version of KS18 do we talk about? The 500 W with old PCB or the new 800/ 1100 W with the latest PCB?

And regarding the IPS vs. KS. I own an IPS 350. That has much more problems than the KS18 and ends in motor blocking.

But there's maybe an other issue: Recuperation. It's my feeling only, not proofed with measurements, that the KS18 doesn't benefit as others (Firewheel, MSuper) from recuperation.

[Cloud]

 

1. Inserting ventilation creates water ingress problems

 

why not creating an opening from the control board compartment into the chamber where the wheel is located , install an exhaust fan and suck the heat down along the circumference of the wheel and suck in the colder air along the circumference of the wheel on the other side? The opening into the wheek compartment coukd be via a bent ( gooseneck) tube to prevent splashing water up into control board area. Maybe have a small drain ( opening) in gooseneck to get ride of water that still gets in.

[Cranium]

 

Back in the day, my physics teacher always said that if you suspect the equation to be wrong, inspect that you get correct units out of it  

Edit: so to clarify: the point was that your original equation states that:

But you only get 425 WATTS out of it, if moving at 1m/s (because otherwise the result is newtons, which is different than watts).

</nitpicking>

0 m/sec is what I was using (standing still is what I was  calculating for) and it does give you watts.  In your equation you mentioned in your previous post (weight (kg) * gravity (constant) * sin(angle of hill) * speed (m/s)), it breaks down at 0 speed and results in 0 watts no matter the angle or mass which would break the laws of physics for the given problem.   

We should take the physics discussion to another thread and lets get our equations tweaked.

[OliverH]

With an upgraded battery pack the motor may be still get more power and more heat. The whole kit is currently not set up perfect on the bench (I'm addressing all manufacturers with this sentence) or as always only with 60 kg riders and not guarantee weight. That's why the US and European (bigger/ more in weight) riders are faced with problems/ limitations the Asians doesn't have.

[zlymex]

0 m/sec is what I was using (standing still is what I was  calculating for) and it does give you watts.  In your equation you mentioned in your previous post (weight (kg) * gravity (constant) * sin(angle of hill) * speed (m/s)), it breaks down at 0 speed and results in 0 watts no matter the angle or mass which would break the laws of physics for the given problem.   

We should take the physics discussion to another thread and lets get our equations tweaked.

Ideally in a motor, it is the current that create force/torque which will hold you there on the slope. Current not necessarily creates power as in the case of superconductor or permanent magnet.
However in real world, motor coils has resistance, there are also voltage drops in MOSFETs that generate power when EUC not moving on the slope.
The power and speed relationship(for an EUC on a slope) may thus represent roughly but better in the form of:
power = A * speed + B
where A and B are two constants dependent on EUC, weight, slope angle etc as discussed earlier.
If the speed is zero, the power equals B which is not zero.

[zlymex]

Comparatively, I don't think the King Song has more heat dissipation issues than other brands. There are probably three issues at play: 1) the IPS control-board has a block of aluminum which has twice the mass of the KS, 2) because the peak power in the KS is so much higher (at least 2x more than current IPS's) riders will be pushing their KS harder than most other brands, 3) heat has a tendency rise, the control-board is located in a small enclosed space at the top of the Wheel—even though it's exposed through the Wheel housing, heat transfer of air is not very efficient.  

King Song are well aware of the susceptibility to overheating if pushed hard, but there's no easy fix for the moment:

1. Internal fan without ventilation won't do very much
2. Inserting ventilation creates water ingress problems
3. Larger heat-sink has marginal benefit
4. Heat-sink fins (on the tire side) might be effective, but the current design of the shell doesn't have space for this
5. A heat transfer plate to an inner-lining of the wheel housing could help but binding two pieces of metal together, while still making it serviceable is tricky

 

It could due to my poor English but I have three doubts:

1. "Larger heat-sink has marginal benefit"(which I agree), but why issue one: " the IPS control-board has a block of aluminum which has twice the mass of the KS"?
2. "King Song are well aware of the susceptibility to overheating"(which I agree), but why "I don't think the King Song has more heat dissipation issues than other brands"?
3. When we were climb the hill together with KS18‘s rider, we were at the same speed, similar weight, and the small pedal size make his foot sour, but how he may "pushed hard"?

[zlymex]

There's current passing through the mosfets in both occasions (acceleration and braking), just the direction will be different (from batteries, to batteries), so it builds up heat either way, the more power drawn from batteries (or generated by braking), the faster and higher it heats up. ............

Agreed. Once I did a test riding on a slope up and down three times on my MSuper in the hope to find the cause of heats-up, the graph below is the result elevation and speed vs distance from a GPS app(elevation is barometric based that is more precise than GPS in relative term). I also made current, voltage and temperature samples(by a data logger) at 0.1sec interval. I marked the temperature(in degree C) in green letters on hill tops and bottoms.
It seems that downhill has little heats-up than uphill. Later I calculated from the sampled data that total uphill and downhill efficiency to be 55.6% and 57.8% respectively. If the motor efficiency is 60%, then the efficiency of the board would be  92.6%(uphill) and 96.3%(downhill) making the loss of 7.4% and 3.7% respectively.

Uphill efficiency here is define as the potential energy lifted divided by the Wh consumed from the battery.
Downhill efficiency here is define as the Wh charged to the battery divided by the potential energy lost.

Interesting to know that when uphill and back, about one third of battery energy can be recovered(55.6% * 57.8%).