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KS S20 126V Requirement Debate?


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While I find the use of 126V promising for combining torque with speed, i could do without it as I rarely ride faster than 50Km/h. The 30S configuration also had me a bit worried but if the smart BMS was smart enough it might be doable(?)

Just my 2c here, experimental and fast is nice but I’d go with the safer version given the choice. My main grief if it went down to 100.8V would be charging speed (Compensating for the smaller battery compared to the Sherman) not top speed.

Tl/dr: If I bought the S20 it would be for riding far with the added comfort from the suspensions, hence 100.8V wouldn’t be a deal breaker.

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I was messing around with my car charger I am making for my 16X at 84V and laid my arm across the back of the connector and got a pretty good tingle. This will be much worse at 126V and could cause a safety concern. They say dont touch the 350V yellow wires in a tesla electric car or it will be the last thing you do.

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2 minutes ago, The Brahan Seer said:

I thought the higher the voltages the lower the resistances and better efficiency, thinner wiring required etc. Lower heat. But I am not an electrical engineer.

Higher voltage will draw less current from the packs, however for the given power output used by the controller, each cell will be drawn the same current regardless of the pack configuration.

I would be happy to learn from an explanation about what @Jason McNeil describes regarding internal cells resistance adding in a series configuration vs a parallel one.

To output 360W with cells at 3.6V, I guess that:

  • 1s10p pack would have each cell running at 10A for 3.6V 10A total.
  • 10s1p pack would have each cell in series running at 10A for for 36V 10A total, however each cell resistance is adding up in the series so you might get only 34V instead of 36V: a less efficient configuration

Is that correct?

2 minutes ago, The Brahan Seer said:

It could result in production delays, cost overruns and other unknowns. Or it might do the opposite and increase production, lower costs and offer other great benefits.

Sounds like to me you are worried that the S20 won't meet the specification and launch date. Which is a valid point. But I wouldn't suggest holding back innovation. All good things come to those who wait.

I think that part of that is more a dealer's perspective, which makes sense in @Jason McNeil's position.
It's a higher risk product, which is bound to make a dealer uncomfortable for all sort of reasons.

I decided to vote with my money with a pre-order, to confirm that it is the right direction.
However I have no doubt that the S20 will be very late and have plenty of issues, launching with an immature technology that won't be thoroughly tested.
At the same time, I have a first-batch 16X (bought second hand) that's awesome, so maybe it won't be that bad.

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17 minutes ago, yoos said:

That is correct except about the configuration efficiency. Suppose internal resistance of 0.1 Ohm per pack (I don't know the actual value), then the 1s10p would have a voltage sag of 10 times 10A x 0.1 Ohm = 10V, while the 10s1p would sag 010A x .1 Ohm = 1V. In either case the voltage sag would be 1/3.6 = 10/36 = 27% of nominal voltage of the EUC, which effectively drops your top speed by 27% in either case.

Thanks!
So a 120 cells pack in 30s4p would be the same as 24s5p in terms of loss, efficiency and operating temperatures, addressing @Jason McNeil's concern following.

2 hours ago, Jason McNeil said:

increased series internal resistance—leading to higher pack operating temperatures

 

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11 minutes ago, supercurio said:

So a 120 cells pack in 30s4p would be the same as 24s5p in terms of loss, efficiency and operating temperatures, addressing @Jason McNeil's concern following.

Again, not that simple :) indeed, the voltage sag, dissipative energy losses (ohmic heating) within the battery pack would be the same, but there are other elements -- wires, mosfets, the controller etc which might react differently. In one case you have 10A @ 3.6V and in the other 1A @  36V. If the current is then passing through a single cable the voltage sag of that cable is I R (Ohm's law, R being resistance), so lower current is preferable. And the heating would be I^2 R so again, lower current is better. Ultimately, you can afford to use wires with higher R (thinner wires) in a higher-voltage EUC. At the same time you need better insulation to protect from shorts. And then there is the controller which is a complicated piece of electronics. 

Edited by yoos
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1 hour ago, supercurio said:

 

I think that part of that is more a dealer's perspective, which makes sense in @Jason McNeil's position.
It's a higher risk product, which is bound to make a dealer uncomfortable for all sort of reasons.

 

I didn't realise he is a Supplier and so his viewpoint makes total sense to me now. This is a very tough product to sell without any on-going issues. I appreciate 'the risk' these guys take on and the potential rework too. A big thanks to the suppliers for all the hard work they do. Respect.

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I would have been satisfied with a 100V wheel, assuming they could pull similar performance metrics as an RS torque. Heating and battery pack concerns aside, it's annoying to be forced into yet another proprietary charger, but we'll need to wait until the wheel is out in the hands of some actual users and testers before we can tell if proposed bump in performance is worth all these unknowns. 

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When I first heard the 126v announcement coupled with otherwise 100v speeds, my first thought was: why? As this won't be used to achieve some new top speed (as we all know Begode or Veteran would have done), and any slight improvement to acceleration and/or "power efficiency" are likely to be merely theoretical while the reality is somewhere between negligible to completely undetectable, it just sounds like a lot of extra risk (everything from electrical/hardware failure to fire) with no tangible benefits--and therefore likely screams more of a marketing ploy than a product feature. (Particularly for the last active EUC manufacturer to have never even made a single 100v wheel.)

And now based on the pre-order info currently listed on eWheels, it's also looking like of all the new wheels announced, the S20 will be the very last one released--which seems to reinforce the King Song premature rushed announcement/launch pattern I've written about elsewhere.

Edited by AtlasP
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6 minutes ago, AtlasP said:

reality is somewhere between negligible to completely undetectable

This may turn out to be true given KS's aversion to top speed, but a similar argument could have been made about the jump from 84V to 100V. Perhaps they just want to accelerate a 20" wheel like they do their 16"? Maybe they don't want to end up in flames on @Jack ex-KS's burnout hill... he promised he'd do a video even before he left. Might not have wanted @Marty Backe to note that it "runs hot" on his 5k hill climb... KS has proven to have pretty good margin on heat buildup under sustained power demand. We won't know how 126V plays out until it's been in the field for a while.

7 minutes ago, AtlasP said:

King Song premature rushed announcement/launch pattern

Keen obversation... but it saved you a kilobuck on the Hero. And you can bet LeaperKim and Gotway are both scrambling, distracted from other pursuits chasing what might be a squirrel.

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1 hour ago, Tawpie said:

This may turn out to be true given KS's aversion to top speed, but a similar argument could have been made about the jump from 84V to 100V.

Quite the contrary, the 100v wheels have a clear and obvious and unquestionable benefit over 84v wheels in top speed and safety headroom. I suppose King Song could argue that their 126v wheel will have better safety headroom when staying within 100v speeds than merely a 100v wheel, which may be theoretically true--although this potential benefit is offset at least initially by the risks inherent to an entirely new set of electrical components and platform for King Song which needs developed and tested and refined. But maybe that's the true long-term potential value proposition.

Quote

Keen obversation... but it saved you a kilobuck on the Hero. And you can bet LeaperKim and Gotway are both scrambling, distracted from other pursuits chasing what might be a squirrel.

Can't/didn't save me anything on a wheel (the Hero) I was never going to buy in the first place. ;-)

Edited by AtlasP
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126V is clearly much better for EUC performance and durability of internal parts that might be damaged by heat (less heat from the same power output). Would be very exciting to see this breakthrough. We will all benefit in the long term if KingSong can pull it. ...But...

(Battery aspects aside) Does higher motor voltage mean much greater building quality requirements (wiring insulation, motherboard size, overall weather tightness)? 

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https://evannex.com/blogs/news/tesla-s-4680-cell-is-a-stroke-of-genius-sandy-munro

https://www.allaboutcircuits.com/news/just-how-much-breakthrough-teslas-tabless-battery-cell/

 

Tesla tabless 4680 battery.  (Still in development, yet to be mass produced)

Simpler and cheaper to produce.

5x energy density.

6x power.

Larger battery rather than many smaller batteries, 30-40% less steel casing required.

 

Less resistance, less power loss, less heat generated.

Less likelihood of manufacturing defect of welding burrs causing internal short circuit, causing fires and explosions.

Tabs can affect battery reliability and performance.

Welding tabs, an additional manufacturing step and cost.

Non uniform distribution of current, and non uniform utilization of active materials that coat the electrodes.

 

Maximum distance that electrons should travel is the height of the electrode rather than its length as in the case of a conventional tabbed electrode.

Current distribution will be uniform across the tabless electrode.

In this way, local hotspots with large overpotentials that can cause unwanted chemical reactions are avoided and the battery's lifetime is improved. 

 

 

With the tabless design, the whole edge of the electrode is responsible for current (and heat) transfer. Heat transfer occurs through an area as large as the base of the battery cylinder. When the anode and cathode sheets of the new battery are rolled up, it forms a rose-like gathering at the ends.

 

Tabless_battery_cell.jpg

 

_____________________________________________________

 

Maybe in a few years, EUCs will be using Tesla's 4680 batteries.

 

 

 

Edited by Paul A
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a lot of promising battery prototypes... even Czech project HE3DA seems to be big unknow now (its extremely hard to ignite it, even with bullets or crashtests - no Jack, please leave it alone, dont touch! But is that enough?...).

 

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17 hours ago, Tawpie said:

To me, it's a bit like gigahertz on PC CPUs... easily understood by the unwashed but not a true measure.

Or more pixels = better camera. I hope this is not what is happening with the 126V thing. By reading the discussions around the topic on this forum I get the feeling that very few truly understand the topic and the rest just see higher number as better. I don't mind more voltage as long as there are no big negative side effects.

I also understand the want for progress. But personally I see many other features as more important developments. For example lights, suspension, comfort, range, reliability, ease of tire change. I'm personally very likely to purchase S20 next spring. But voltage has nothing to do with my purchase decision. On the other hand increase to 126V is the main reason I will not pre-order and will wait to see how reliable it is. I would be perfectly happy with 100 or even 84 volt S20. I'm already content with current speeds so I just don't want to have any costs (monetary or otherwise) with the unused potential. 

I appreciate Jason's concern of negative side effects of increased voltage for very little benefit for most riders. 

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23 hours ago, Jason McNeil said:

There is quite a lot of buzz surronding the 126V battery pack on the S20, but I haven't been able to find much in the way of dissenting voices of whether this ambitious specification is necessary, desired & what trade-offs would be the consequence of this 30s4p pack configuration.    

 

TLDR: "It sounds like a you problem...until it's not"

 

We are in the honeymoon hype phase, post-product launch, pre-reality.

I'm sure there are a lot of dissenting voices from the people that have to design, engineer, manufacture, QA, retail, and warranty this new 126V tech.

From a rider/consumer POV, it's sounds like it might give us that low-speed, rocket-boost torque that feels so exhilarating, while also providing more safety headroom at high speeds.

eWheels' great warranty service, for better or worse, allows riders not to care about things like "is this a good idea" and just enjoy the ride.

Once the wheel becomes reality and starts shipping, I'm sure you will find the much sought after community dissent, in spades.

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