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King Song S18 Discussion


Phong Vu

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11 hours ago, Finn Bjerke said:

compare video very nice: 

 

Good comparison. Shame the issues of both pre-production models, slow down the times. Would be interested to see them so it again, but with later batch production versions when they have ironed out the issues on both EUC. 

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A cut out can be reversible if you catch it and lean back quickly IF the wheel can rebalance quickly enough. Most cut outs on modern wheels happen at or near top speed and there is no way to lean back in time as no warning is given outside of the pedal dip. I ride my 16s more aggressively than I should and have had two cutouts, I barely recovered both because they were due to heavy acceleration from a standstill vs a top speed cutout. As soon as the pedals took a heavy dip (feels different than a normal dip which I do get at top speed occasionally) I threw my weight back and could feel the wheel “catch up” and lock back in balancing. I’m not concerned with it because now I know what I can and cannot do. 
 

3p configuration lowers the safety margin on aggressive acceleration and I do believe this motor is too powerful for the battery but that would only affect people who ride at high speeds and high accelerations.  Your average rider at average speeds and acceleration would be far less likely to have this situation occur. 
 

I wonder if the external battery pack would give it the juice needed to widen the margin?

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Just got a message from ewheels.com about the third batch (from the July to present):

Quote

KS are making some changes/improvements to Batch 3 based on some of the criticisms, they held back shipping the batch 3 orders; awaiting news from the factory before sending out the next update. 

I almost decided to cancel the order, but maybe they'll fix the problems with suspension in this batch.

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4 hours ago, Stanislav said:

Just got a message from ewheels.com about the third batch (from the July to present):

I almost decided to cancel the order, but maybe they'll fix the problems with suspension in this batch.

Haha. So what about batch one and two? Will they get the fixes too?

 

 

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47 minutes ago, Steef Klonoa said:

What is the extent of the issues they would be fixing anyways, just the suspension linkage/bearings?

It is still unclear the extent King Song is currently undergoing in "making changes to address the criticisms".  I have personally contacted @Jack King Song on a number of occasions to get some clarification and currently still waiting to hear directly what changes will be implemented. 

At this stage, the biggest issue has been the poor assembly methods used due to a poor understanding of how the pivot bearings inner race should have been correctly mated to one another/clamping bolts, rather than the actual bearings themselves!  The other main issue with the slider tubes possibly being pushed out of parallel in some cases with the assembly blocks having been left in place. 

Ironically, a recently posted YouTube video showed a customer in the UK, that bought 2 S18's and one had the blocks still fitted but the second one had a different pedal hangar, with No Blocks necessary!  I've asked Jack if this one of the changes they are making, so still waiting to hear back, but will post here if I hear any news!

118535165_856911591802355_68533879048250

Edited by fbhb
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1 hour ago, Seba said:

With voltage drop of just 5 Volts and current of 30 Amps power dissipated as heat would be 150 Watts, leading to quick overheating and failure. So, faulty or underrated battery is most probable case of such a battery sag.

Btw: at max power output - half no load speed and just before overlean (battery current==motor current, 100% duty cycle) the efficiency is 50%!

So only one half is the mechanical power output, the other half is burned at the batteries internal resistance and the motor coils...

So there are some kWs used for heating... :(

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21 minutes ago, Chriull said:

The S18 has a 20s3p config and the datasheet afair says 25mOhm per cell? So 0.16Ohm internal resistance for the whole pack.

Gives almost 9V sag at 53A.

You're right! :) I didn't calculated battery internal impedance, just assumed (wrongly) that it's not that high. So we have confirmation - S18 battery pack may not be adequate for extreme riding or hard accelerations.

21 minutes ago, Chriull said:

I did not find the video :( The battery was full 84V just before this started?

No, it was ~72 V at rest.

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5 hours ago, Seba said:

You're right! :) I didn't calculated battery internal impedance, just assumed (wrongly) that it's not that high. So we have confirmation - S18 battery pack may not be adequate for extreme riding or hard accelerations.

Imo the no load speed (~lift cut off speed) would be the most important value in relation to max tiltback speed.

As, for example afair for the ks16x these both values were a bit close. The ks16s imo had a much nicer relation.

And the tiltback as max speed gives the riders a totaly wrong feeling of safety - gw riders with tiltback disabled will be much more carefull reaching the limits. Which are mostly just higher with gw wheels for the latest generations...

Battery config (internal resistance) "just" determines the steepness of the limit line from the no load speed. Together with the coil resistance.

I have no idea how the battery sag during high burdens caused by the "sophisticated" equivalent circuit with the huge capacitor will interfere with this low p config, but i'd assume it's going in the direction of the early generation wheels with low capacitance batteries. 

So maybe like the ks16x ist best safely driven with a 40-45 km/h limit instead of the 50 km/h limit.

So tldr i'm most probably with you that the battery config for this wheels spec are not adequate - battery capacity is not only for range but very important for safety!

But still a nice wheel (once the bearing issues are solved) for riders with moderate higher speed abilities.

Quote

No, it was ~72 V at rest.

That'll be a bit low for above numbers - but no matter, serious analysis should only be done with logs. Some numbers seen in a video can lead to many "ambiguities" too easy...

Edited by Chriull
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6 hours ago, Seba said:

You're right! :) I didn't calculated battery internal impedance, just assumed (wrongly) that it's not that high. So we have confirmation - S18 battery pack may not be adequate for extreme riding or hard accelerations.

This information afraid me for S18 users because a lot of them buy S18 for look - suspension and hardcore ride / off-road ... then not safe at all for this use.

It’s a hardware problem with no software solution ... :-(

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5 hours ago, BondZero07 said:

This information afraid me for S18 users because a lot of them buy S18 for look - suspension and hardcore ride / off-road ... then not safe at all for this use.

It’s a hardware problem with no software solution ... :-(

Well for short off ride intense (for me anyway) rides like I enjoy, the S18 rocks over my old MSX.  Thanks to its now dialed in suspension, I can almost keep up with my dog Loki.  He's done 28 mph in snow with the MSX, and now that the summer heat is wearing off... well I wouldn't be able to do this speed on this rough terrain nor endurance with the MSX.  We have done this same rout before w/ MSX, but speed was under 10 mph most of the way.  Anyway, here's a ride I couldn't do without a suspension and an off-road worthy tire (K262).   Also, the suspension is 200/100 (pumped unblocked) with rebound full open (most responsive, cushy ride).

 

Edited by Elliott Reitz
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22 hours ago, Chriull said:

I did not find the video

Just found and watched it - https://www.youtube.com/watch?v=3hwX8Mu3ZcA&t=42s

 

20 hours ago, Seba said:

No, it was ~72 V at rest.

The one i've seen starts with 79.7V/77%, and your mentioned 67.7V @ 53A (7:23). start 7:20, overlean @ 7:24 with 44 km/h. About 3 m/s² acceleration. I typed the couple of values in an excel sheet - more or less a very similar picture to the KS16X overlean

Just the declining graph, once he hit the limit goes down very steep - would mean a far to low lift cut off speed?

Or, as he mentioned a little bit later on in the video that EUC World disconnected - that the cells really broke down due to overburden!?

He mentioned he did a couple of acceleration tests before...

BTW - anyone knows the S18 lift cut off speed?

ODe6t1B.png

I took here 0.2 Ohm as internal resistance to get "U no load" - as in the datasheet of the LG 21700 50T they give 30mOhm as initial DC resistance at 0.5C...

pu8f8qr.png

 

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On 9/6/2020 at 9:00 AM, Seba said:

You're right! :) I didn't calculated battery internal impedance, just assumed (wrongly) that it's not that high. So we have confirmation - S18 battery pack may not be adequate for extreme riding or hard accelerations.

No, it was ~72 V at rest.

72 V at rest is dearly drained to 0. Nobody should expect full performance that close to the edge of discharged.

3 hours ago, Chriull said:

BTW - anyone knows the S18 lift cut off speed?

42 mph (67 kph).  But its not like an ordinary lift cutoff because when it gets to 31 mph in free spin it "runs away" going faster and faster without responding to any tilting response until it cuts off (coasts to 0 mph) and the app says it got to 42 mph.  BTW, the MSX 100V free spins to 59 mph then cuts off very fast via rapid reverse torque to 0 mph.

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2 minutes ago, Elliott Reitz said:

72 V at rest is dearly drained to 0. Nobody should expect full performance that close to the edge of discharged.

Don't forget we're talking about 84 V battery, not 100.8 V :)72 V equals to 3.6 V per cell, which translates to ~60-70 % SoC. 

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18 hours ago, Elliott Reitz said:

42 mph (67 kph). 

With fully charged batteries? That would be less than ks16x with ~76 km/h... Edit: Got this from some type - KS16X has ~67 km/h lift cut off speed, too.

Afair Wrongways euc world screenshot showed a max speed of 65 km/h, but unfortionately without battery voltage....

Quote

its not like an ordinary lift cutoff because when it gets to 31 mph in free spin it "runs away" going faster and faster without responding to any tilting response until it cuts off (coasts to 0 mph) and the app says it got to 42 mph.

This could be the result of the wheel trying to tiltback - but beeing lifted it has no chance to tilt the pedals so it's going on to accelerate.

Edited by Chriull
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