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Excitement about KS16S Sport?


dpong

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18 minutes ago, Dingfelder said:

... local safety laws in China?

:roflmao::laughbounce2:   I've never been to China, but have you seen some of the living conditions there?  The piles of electronics refuse and people piling tons of stuff onto the backs of trucks and bicycles?  Some of the products showing blatant lack of safety for consumers seem to indicate that it's sort of the wild west over there -  as in do whatever you want, and try not to get caught sort of lawlessness.  Using cadmium in kids jewelry, lead in paint for kids toys, and melamine in milk powder are just a few examples.  Business dollars come first, safety somewhere down the line if the manufacturer is interested in it.

Maybe @John Eucist can chime in with a first person's viewpoint,  but to me it sounds like the government gives more or less free reign on manufacturer design.  I could be totally wrong of course.  :whistling:

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2 hours ago, Marty Backe said:

Yeah, that's the craziest feature. They have good intentions, but it just upsets everyone but the first time buyer. And what a way to make repeat KingSong customers happy.

Fortunately there's a way to unlock their wheels (I assume it still works with their newer wheels).

Yup, @esaj already tested it with a KS16S.

 

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5 hours ago, dpong said:

I agree, an extra fuse is mind boggling, an expectation created that you might need it, and terrible optics. Just terrible.   

I don't know... My cars all have a lot of fuses. They also come with spare ones, just in case. Even so, the last 20 years none of these blew in any of the cars I drove. It's just common sense to have a more or less mechanical primary fuse in the line to prevent cables melting down and catching fire in case of a catastrophic electronics failure. MOSFETs can blow in a way that they create a short. Well, but there is the BMS which should then discopnnect the battery, you may think. Well, the BMS also uses MOSFETs to cut power. They may also blow and short their terminals. Then what happens is something like this:

Once the controller board causes a short, you'll faceplant anyways. I'd rather fall off and have the fuse blow on the wheel to stop over-currents, than having to deal with burned legs and a burning 800Wh battery pack. Check out this guy, how the first fire extinguisher doesn't work and he runs for a nearby one... scary.

The KS16-S now has separate fuses for the two packs, 30A each. That should be fine. Chris from 1RadWerkstatt told me 'no worries' these fuses are OK now.

 

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On 21.5.2017 at 3:24 AM, Dingfelder said:

Well written, I appreciated the explanation.  And for once I understood it!  Most of this stuff usually goes over my head pretty quickly, but I drew value for your post.

Thanks! Let me add a graph showing what I was talking about. Observe the green curve, showing motor efficiency. Note how it rises quickly but then goes down significantly as the motor load approaches its maximum power output. The engineers designing our wheels must carefully select / engineer the motor to operate at a reasonable point in this graph. Standard load while cruising (long term load) should put the motor right at the place which is denoted as 'rated operating point' in the graph below, with ample headroom until max power output is reached, for example when climbing a steep hill or riding through a pot hole.

XN1f9.jpg

Since the KS16-S has a stronger motor, its operating point will be more to the left of the graph compared to the 800W motor (given the same power demands). This may mean better or worse efficiency.

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6 hours ago, Christoph Zens said:

I don't know... My cars all have a lot of fuses. They also come with spare ones, just in case. Even so, the last 20 years none of these blew in any of the cars I drove. It's just common sense to have a more or less mechanical primary fuse in the line to prevent cables melting down and catching fire in case of a catastrophic electronics failure. MOSFETs can blow in a way that they create a short. Well, but there is the BMS which should then discopnnect the battery, you may think. Well, the BMS also uses MOSFETs to cut power. They may also blow and short their terminals. Then what happens is something like this:

Once the controller board causes a short, you'll faceplant anyways. I'd rather fall off and have the fuse blow on the wheel to stop over-currents, than having to deal with burned legs and a burning 800Wh battery pack. Check out this guy, how the first fire extinguisher doesn't work and he runs for a nearby one... scary.

The KS16-S now has separate fuses for the two packs, 30A each. That should be fine. Chris from 1RadWerkstatt told me 'no worries' these fuses are OK now.

 

I still contend that fuses in the EUC application is a lazy (cheap) design choice. The EUC can be designed to withstand any real-world load and if the load is still exceeded the electronics could shutdown. Takes more circuitry to do this however. My house is filled with electronics that don't have fuses.

The negative consequences of a blown fuse in the EUC should preclude their use, IMO.

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13 hours ago, Christoph Zens said:

The KS16-S now has separate fuses for the two packs, 30A each. That should be fine. Chris from 1RadWerkstatt told me 'no worries' these fuses are OK now.

While I don't think the fuses are a bad idea, I wondered why they used two separate fuses? I guess if one pack somehow fails and short circuits over the fuse, it would only blow that one and isolate the faulty pack... But, on the other hand, if only one of the fuses blows, you won't notice it until you suddenly realize your range has about halved (or that the battery voltage drops faster than usual). And if it's due to too high current draw by the motor, if one of them goes, all the load will drop on the other 16S2P-pack, and will likely blow that fuse too, like a cascading failure?

In other news, I was too hung over and tired to go for a ride yesterday, but I did ride about 32km trip this evening (measured from map, not from the app mileage). Not that fast ride again, my average speed was probably somewhere around 20km/h or slightly above. This time the wheel was charged to full yesterday, although the voltage (according to the app, which might be wrong) was around 65V when I checked it while riding after about half a kilometer. I just had a recent chat with the friend owning the KS16B, and he reminded me that when we measured his charger last summer, it gave out only about 65V (don't remember the exact value), although some of it might be also due to the not-so-good multimeter I used back then(?). Have to check it again once he visits. Anyway, I had completely forgotten about that, but remembering it now, I checked the charger that came with my KS, but it gave out 67.398V, this time measured with HP34401A, a much more precise bench meter, that gave out correct voltages the last I checked it against  0.04%-tolerance precision voltage references, the base accuracy should be 0.0035% for DC voltages, but I bought it used and it hasn't been calibrated in years.

When I came back, the app showed 60.0V and 63% of battery remaining. I don't know how trustworthy these numbers are, and since there are reverse voltage protections in the BMSs, I can't get a voltage reading without opening up the shell. But based solely on those app numbers, I still think getting 70-80km range with my weight is possible for the 840Wh packs, these weren't even ideal conditions, the last 10km of the trip was with stronger headwind and the temperature was around +12C (54F). I need to use the Charge Doctor tomorrow to see how many watthours the packs take, although even if it weren't all the way up to 70-80km, it's certainly seems enough. No more range anxiety  B)

This time I wore the "proper" hiking boots, and didn't have much problems with foot fatigue. I did take a couple of stops on the way though, once I had to take a leak ;) and then stopped at a friends place for about 10 minutes to have a smoke. I also learned to move my feet by putting weight on the ball of the foot, shifting the heel, and then in reverse, weight on heel and shifting the toes. A bit fidgety but it makes it possible to correct the foot position while riding, if needed.

On steeper hills, I noticed I needed to clench the wheel a bit while leaning to get it to accelerate faster, or stand more tiptoed. Might be that the stronger motor is "too strong" in the sense that it keeps the wheel easily level at the stiff-riding setting, and my weight is too small to cause a large enough tilting force when simultaneously going up a steep hill. :D Don't know if it's an issue for heavier riders, maybe they can exert enough force to make the wheel accelerate easier. I didn't try the other riding modes yet, but using a softer one (as long as it's not too soft) might help.

Need to fill up the tire to a higher pressure too, it was now around 3+bar (45 psi), which is still too low, but I didn't want to go to higher pressures immediately after such a long pause. In general, I now got much closer to "how it used to be", ie. I don't need to concentrate on the actual riding (controlling the wheel) much at all, I can control the wheel more subconciously and just enjoy the the ride. In a week or two I expect it to be just like before, with the wheel feeling more like an extension to my body rather than a separate thing ;)

Oh right, the pedals are like these:

capture-d-ecran-2016-12-13-18-29-38.png

The black part appears to be plastic (the small weird "bar" seen on the left was some kind of rubber or cell foam glued there, I ripped it off, probably just for shipping), and there's grip tape on the front and back, with the King Song-logo/text in the middle. They are wide enough for me (42-size foot), but could be maybe a bit longer. They are also very stiff when you fold them in, not easy to get them unfolded with a single hand (and forget about trying to do that with your foot). Might be just that the axle screws are set pretty tight.

The other type of pedal I've seen in images is like this:

Kingsong-KS16-schwarz-elektrisches-Einra

I've seen pictures marked as KS16S having both pedals, but some of those might be of the B-model. Or then they ship S's with different pedals depending when they were made. Once I get the B-model (in transit), I'll check which kind it has.

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1 hour ago, esaj said:

While I don't think the fuses are a bad idea, I wondered why they used two separate fuses? I guess if one pack somehow fails and short circuits over the fuse, it would only blow that one and isolate the faulty pack... But, on the other hand, if only one of the fuses blows, you won't notice it until you suddenly realize your range has about halved (or that the battery voltage drops faster than usual). And if it's due to too high current draw by the motor, if one of them goes, all the load will drop on the other 16S2P-pack, and will likely blow that fuse too, like a cascading failure?

I think the two fuses are necessary now that they changed the way the two packs are connected to the board. With both packs being connected to the controller board independently, there simply is no place to put a single fuse in series of both packs (electrically speaking). So each pack needs to be protected by its on fuse right where it enters the controller board. As I understand this new design, the controller now manages both battery packs independent of one another, like two redundant power supplies. They are no longer hard-wired in parallel. Theoretically, this could allow for one fuse to blow and the controller, detecting that one of its supplies is gone, could issue an emergency tilt-back-please-get-off-ASAP warning. Usually, power requirements during normal crusing stay well below 30 amps, so depending on the root cause of the first failure, the wheel may get enough power from the remaining pack to safely come to a controlled stop.

However, I don't think that's a scenario considered by KS. They just need the two fuses because there are two separate battery packs connected to the controller.

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21 minutes ago, Christoph Zens said:

I think the two fuses are necessary now that they changed the way the two packs are connected to the board. With both packs being connected to the controller board independently, there simply is no place to put a single fuse in series of both packs (electrically speaking). So each pack needs to be protected by its on fuse right where it enters the controller board. As I understand this new design, the controller now manages both battery packs independent of one another, like two redundant power supplies. They are no longer hard-wired in parallel. Theoretically, this could allow for one fuse to blow and the controller, detecting that one of its supplies is gone, could issue an emergency tilt-back-please-get-off-ASAP warning. Usually, power requirements during normal crusing stay well below 30 amps, so depending on the root cause of the first failure, the wheel may get enough power from the remaining pack to safely come to a controlled stop.

However, I don't think that's a scenario considered by KS. They just need the two fuses because there are two separate battery packs connected to the controller.

Ah, ok, so there's actually something more clever going on than just fuses and connecting the batteries to a single power rail right after them. Now that you mentioned it, looking at this picture, it would look like the fuses might actually sit on the low-side (right next to the black wires), and the 4 milliohm(? I think, marked as R004) resistors could actually be used by the board to measure current per pack?

 

Kingsong-KS-16S-kontroller-8.jpg

 

Also, I'd expect them not to blow right at the moment the current goes above 30A, otherwise they'd blow just by the charging current drawn by bypass capacitors?

The blue wires seem to be some sort of dataconnections to the packs, so apparently the board also communicates with the BMS's.

Kingsong-KS-16S-kontroller-1.jpg

 

 

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I guess that the 2 pcs of 30A fuses are used as there is no higher amperage fuse in this form factor than 40A (used in regular KS16)  I can not see from the pics if they work in parallel but I guess that they do in fact...  so this way they have created 60A fuse...

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My KS16S is still on the way... when it arrives I will have a look on the PCB for sure while installing extra red lights on the side battery covers... I have found nice LED panels which I have already used on my backpack... (red and white) They are powered from 12V but little LM2704 step up converter + 2pcs of 18650 cells will do the trick..

 

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1 hour ago, esaj said:

Also, I'd expect them not to blow right at the moment the current goes above 30A, otherwise they'd blow just by the charging current drawn by bypass capacitors?

@Sidestreet Reny would blow fuses all the time when performing tricks but I do not recall it occurred by him just riding normally. Is there any inscription on the fuse? Wonder if they are 'time delay' surge protection type fuses.

From what I have read a surge protection fuse must accommodate three overload regions. For a short circuit it must blow fast in the normal way. It must also blow for steady overload currents but it also must tolerate continual brief over-currents -- say ten times its rating -- without blowing or deteriorating.

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58 minutes ago, Lukasz said:

My KS16S is still on the way... when it arrives I will have a look on the PCB for sure while installing extra red lights on the side battery covers... I have found nice LED panels which I have already used on my backpack... (red and white) They are powered from 12V but little LM2704 step up converter + 2pcs of 18650 cells will do the trick..

 

Very cool and highly highly visible!  

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5 hours ago, Lukasz said:

My KS16S is still on the way... when it arrives I will have a look on the PCB for sure while installing extra red lights on the side battery covers... I have found nice LED panels which I have already used on my backpack... (red and white) They are powered from 12V but little LM2704 step up converter + 2pcs of 18650 cells will do the trick..

 

very cool and smart idea!

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21 hours ago, Christoph Zens said:

I don't know... My cars all have a lot of fuses. They also come with spare ones, just in case. Even so, the last 20 years none of these blew in any of the cars I drove. It's just common sense to have a more or less mechanical primary fuse in the line to prevent cables melting down and catching fire in case of a catastrophic electronics failure. MOSFETs can blow in a way that they create a short. Well, but there is the BMS which should then discopnnect the battery, you may think. Well, the BMS also uses MOSFETs to cut power. They may also blow and short their terminals. Then what happens is something like this:

Once the controller board causes a short, you'll faceplant anyways. I'd rather fall off and have the fuse blow on the wheel to stop over-currents, than having to deal with burned legs and a burning 800Wh battery pack. Check out this guy, how the first fire extinguisher doesn't work and he runs for a nearby one... scary.

The KS16-S now has separate fuses for the two packs, 30A each. That should be fine. Chris from 1RadWerkstatt told me 'no worries' these fuses are OK now.

 

I remember seeing this video a long time ago. Am I the only one who finds it interesting that they have so many fire extinguishers literally laying around (no fancy cases or wall mounts for you Chinese).

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7 hours ago, Lukasz said:

My KS16S is still on the way... when it arrives I will have a look on the PCB for sure while installing extra red lights on the side battery covers...

Great! Please let us know what you find out. Judging from the pictures posted by @esaj, it looks like the two packs actually come in separately, with separate current sense resistors and separate fuses. Behind the resistors, they may well be connected together already. I don't think there are any additional power switches on the board, since they are already in the battery packs (BMS). That's maybe what the thin wires are for. They allow the controller to remotely shut down individual packs, if needed.

With the separate inputs, each having its own current sensing, the controller is able to measure battery current for each pack separately. There are two advantages to this approach: First of all, the controller can detect if one of the packs goes bad. This could happen due to aging, an internal battery failure, a bad battery pack connector, or even the BMS shutting down the pack. Without separate monitoring, the controller would not know that in fact one of the packs is not performing the way it should perform. It would still assume to be able to draw a healthy 40A to keep the rider balanced, only to find out in a critical situation that there just isn't enough current available because really only one pack is providing the current while the other one suffers from high impedance, not being able to deliver what it should deliver under normal circumstances. So, this is a safety measure to make sure the power source is OK and healthy enough for safe riding.

Second, the maximum current to be measured is cut in halve. This should increase accuracy of current measurements and reduce strain on the current sensing resistors.

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8 hours ago, Dingfelder said:

Yeah I thought that was weird too.  Reminds me of my days playing DOOM, where you could find spare pistol clips, shotgun rounds, and rocket shells all over the place.

DOOM. I wasted too many days playing that game. Great analogy!

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4 minutes ago, esaj said:

She certainly has big... personality ;)

I'm waiting for the video where she rides the damn thing :popcorn:

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Leaving the wheel on charger with Charge Doctor for about 5 hours, I could cram 373.8Wh into the batteries. Assuming the pack was as full when I did that 32km lap (at that time it was charged almost 24 hours earlier), that would give about 11.68Wh / km consumption. Not bad, although in better conditions and with full tire pressure, I could get closer to 10Wh/km with the Firewheel, I'd expect in more better conditions (warmer, less headwind, full tire pressure) I could achieve the same with the KS.

Charge Doctor was showing 67.1V voltage and 50mA current when I took it off the charger. Apparently the charger voltage drops a bit with load, when unloaded, Charge Doctor was showing 67.4V. Checking the voltage from the app right afterwards, it was showing 66.4V (with the lights on), don't know if there's an issue with the analog design and capacitor/MCU input pin leakages DaveThomasPilot mentioned (ie. the board is reading lower voltage than reality), or if the basic standstill draw with lights on is enough to drop the voltage a little. Or both.

I was supposed to fill the tire to higher pressure today, but by the time I was ready to do that, it was already so late that I thought better not to start running the compressor in the yard. Not that I've ever received noise complaints, even though I've ran circular saw in the garage at 3AM, but still :P

I wanted to try different riding modes, so I set the wheel on "Riding mode" (yeah, a riding mode called Riding mode... the other two are called "Player mode" and "Learning mode"). I was pretty sure it's going to be too soft and I'm going to hate it. Setting off, I didn't notice any softness. At first I thought that the mode had reset back to "Player mode", as I had turned off the wheel after setting it and going outside. It wasn't until I hit some cracks and potholes with some speed going downhill that I noticed that the pedals sort of "swing" back and forth a little bit, like an underdamped oscillator, that clearly wasn't there with the "Player mode", which seems to stay just horizontal not matter what.

It actually turns out that the Riding mode is really good (at least for me). While it isn't really soft, it clearly allows the pedals to tilt a little bit (might be more for heavier riders?). The tilting isn't especially noticeable except maybe for stronger power braking, and sometimes when crossing steeper street corner stones. Why I really like it, is that it handles the problem of getting the wheel to accelerate faster or from slower speeds in uphills, no need to clamp the shell between my legs for my lean to have more "effect". It's still also sensitive enough that I can "trim" my speed with slight movements of my ankles in addition to leaning.

I took it up a lot of hills, and then went to one of the steepest paved hills around to try it while checking the values on the app, and I could just fly up the hill. The app was giving me up to 4kW charging readings when coming down it with while braking all the time, although it might exaggerate the values. In hindsight, I should have tried starting in the middle off the hill, but I did do one go where I crawled up until the hill gets to the steepest parts and then started accelerating up to the warnings. No problems there. :) The app said power used was around 900-1000W (pretty much continuously while climbing, maybe spiking higher here and there) when running up pretty steady speed, and the board temperature was closer to 40 Celsius, but it was pretty chilly otherwise too (about 8C/46F outside).

In the end, I rode about 25km, could have gone for longer but my hands were starting to feel like freezing. I didn't need to stop at all, slight discomfort in my feet at the beginning of the journey, but the last 15-20km no problems whatsoever. Don't know if it was due to the "softer but not really" -Riding mode, or if I'm just getting back to my "old self" after initial breaking in with starting to ride again.

 

 

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17 hours ago, Marty Backe said:

I remember seeing this video a long time ago. Am I the only one who finds it interesting that they have so many fire extinguishers literally laying around (no fancy cases or wall mounts for you Chinese).

Me too, saw it a long time ago and thought it looked staged, so no matter when it caught fire, there would be plenty of extinquishers nearby.

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