KS S20 126V Requirement Debate?

[DjPanJan]

Honestly i dont know nothing about 126V vs 100V i just keep belive engeners and how 126 EUC work in real world (incline test ,charging overherating).

For me is important i need one more charger 126V this is what i know and understand becasue charging under 8A on EUC "TRIP" is just pain.

This is what reality tech me.

Teoretical mas*****tion about 126 VS 100 is not my type of p**n. ( humor/satiristic/joke)

[RagingGrandpa]

5 hours ago, Paul A said:

Tesla tabless 4680 battery. 5x energy density. 6x power.

No!
It's only 0.16 times more energy dense.
("5x energy" referred to single-cell capacity vs 2170, a physically smaller cell.)

https://forum.electricunicycle.org/topic/20078-tesla-4680-batteries/?tab=comments#comment-335491

 

5 hours ago, Miko.cz said:

Czech project HE3DA

100wh/kg.
No thanks. We have 250wh/kg today.

(It's best suited for stationary power applications where mass doesn't matter so much...)

  

1 hour ago, DjPanJan said:

Teoretical mas*****tion about 126 VS 100 is not my type of p**n.

Different strokes for different folks

[Paul A]

Yes, the use of the term "density" is incorrect.

 five times the energy and six times the power of its Panasonic-built 2170 cells....... the larger 4680 has nearly 5.5 times the volume, simply due to larger dimensions

 

 

 

[mike_bike_kite]

On 10/13/2021 at 2:15 PM, 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. 

Another dissenting voice here! Personally I don't think 126V is really necessary. My 100V Nik+ seems to have more power than I'll ever need. The problem with going for a higher voltage is we're back to experimenting and initial buyers acting as guinea pigs. I do like that my Nik+ can charge in 6 hours using the 21700 batteries but I'll admit I'm worried about 100V Gotway wheels occasionally catching fire - I think we'd do better trying to get 100V wheels working reliably before upping the voltage again. I like the S20 but I'm not bothered by the 126V at all.

[supercurio]

1 hour ago, mike_bike_kite said:

I think we'd do better trying to get 100V wheels working reliably before upping the voltage again. I like the S20 but I'm not bothered by the 126V at all.

This might be the point of higher voltage.

The current standard is 100.8V & 70kph max speed (free spin 105 kph), a configuration which puts a lot of stress on the controllers for low speed accelerations and climbing scenarios.

It's nowhere near as bad on a Nikola+ which has a free-spin of "only" 77 kph, giving it an easier time producing low speed torque. It climbs well and without fuss.

Instead, 126V (or more later) might be the main way to make 70kph+ wheel work reliably - at all speeds.
I don't want to hear "this is a high speed wheel, of course it'll burn if you try to climb this hill" anymore.

[mike_bike_kite]

Perhaps you have a different definition of "reliably"? I mean things like the wheel doesn't have to be put outside to charge or left inside if it's raining etc. 

[supercurio]

42 minutes ago, mike_bike_kite said:

Perhaps you have a different definition of "reliably"? I mean things like the wheel doesn't have to be put outside to charge or left inside if it's raining etc. 

Yes correct, I would consider safety what's regarding the risk of fire, and weather-proofing how it handles the rain.

These 2 aspects are not particularly related to the battery pack & controller voltage, but are associated with electronics design / QC, and waterproofing in the design and assembly of the unit.

[Mango]

I wouldn't be surprised if they tuck their tail between their legs and release the S20 as a 100v wheel. It still would be the best suspension wheel on the market.

Do I trust my well-being and quality of life to a company that aggressively markets a 126v wheel but who hasn't even produced a 100v wheel? 

[That Guy]

My understanding, regardless how the output of the energy system is used (either torque or speed), the same energy may be delivered either with higher voltage and lower current or lower voltage and higher current. If you decide to increase the voltage, you need to invest in insulation and distances with the higher risk of electric short circuit. If you decide to increase the current, you need to invest in conductors (current generates heats). This comes with a higher risk of damage due to the overheating. 

Similarly, motor with the same power may have either higher torque or higher speed. When choosing between the two you choose between greater number of windings (higher torque) or thicker windings (higher speed) with amount of conductor copper to be more or less equal in both cases. 

Of course, it is more complicated than just the combination of voltage-current and depends on motor geometry/efficiency, wheel radius, etc... 

[Chriull]

42 minutes ago, That Guy said:

If you decide to increase the voltage, you need to invest in insulation and distances

There is no real notable difference if one decides for 67.2, 84,100.8 or 126V. Safe low voltage is the way ninebot went with the z10 ?14s? config - staying below ~60V.

All others or low voltages. Maybe 126V hits another barrier, but maybe not since it is DC.

45 minutes ago, That Guy said:

If you decide to increase the current, you need to invest in conductors (current generates heats). This comes with a higher risk of damage due to the overheating. 

That's something that's not to be solved, especially with modern high power wheels.

Mosfet cooling was and is a big problem from the beginning till now... And mosfet burden raises with the square of the current - so raising voltage and hereby lowering the current is the only solution.

@Jason McNeil- maybe it's a bit comforting to you that for the US market all switching mode power supplies work with 110 V AC eff AC/DC converters. These function by rectifying the 110V AC eff to (up to) 110 * sqrt(2)~150V peak DC. From this (up to) 150 V DC the DC/DC converters generate the needed operating voltages or power the grid driven motors/devices.

So a 126V bldc motor driver (inverter) or all the 126V to 12V/5V/3.3V DC/DC converters are absolutely no rocket sience but well known and widely used standard market electronics!

With all the manufacturers offering ic's with well known and tested/used standard circuitry.

So maybe true that this could raise some probs for EUC manufacturers first time using these state of the art technology for EUC's, but if they had engineers knowing and using the manufacturers datasheets and app notes and having some (little) experience and/or communicate with the manufacturer it should not raise any real problem.

[.....]

It needs be 126v and it needs be the specified size and weight. It needs to work better and safer than previous wheels. Why? Because thats what they FU**ING have been pushing on us since the start. I don't give a rats ass how much more difficult it makes it. I expect results as they were marketed to me. Yes, I expect them to deliver within the timeframe given and within the general price bracket as offered. Why would I trust a company that steals business from their competition, by making empty promises? If even ONE person cancelled an order for a competitor product, based on the release info of the ks20, then its serious and delivery is expected... period! If making it a 126v wheel means its any less safe and the performance is WORSE than previous similar wheels, then we've been misled about that as well. Innovating is a dice roll. You gotta learn to not make bold claims that you arent almost entirely sure of. "chickens before they hatch" and all. KS has agreed and marketed this as a 126v wheel. They put themselves on the hook as guinea pigs. Same as their suspension idea. Win or fail, the community needs to see it happen, as future designs may depend on the results...

Edited October 14, 2021 by ShanesPlanet

[mike_bike_kite]

You say you want 126V but you don't say what real advantage that will give you - maybe they could just put a special 126V sticker on your one? 

[wwwooooqq]

For the same power, the kv value is linked to the torque. The higher the kv value, the lower the torque. Assuming that the free speed of 100v is the same as 126v, it can be understood that the kv value of 126v is lower, that is, the torque is higher under the same current. Then the free speed of the motor is limited by the back-EMF limit, so the speed cannot be increased indefinitely. At high speeds, this back-EMF will also significantly reduce our available torque. The higher the speed, the lower the torque, and the higher the voltage energy Delay magnetic saturation and maintain high-speed torque. As long as the preconditions are well defined, everything is reasonable and it is an inevitable trend.

[wwwooooqq]

Share a practical case that is easier to understand, the actual performance of high-torque motors and high-speed motors in the same model

[Chriull]

7 hours ago, wwwooooqq said:

Share a practical case that is easier to understand, the actual performance of high-torque motors and high-speed motors in the same model

 

[RagingGrandpa]

On 10/17/2021 at 7:14 AM, wwwooooqq said:

actual performance of high-torque motors and high-speed motors in the same model

https://forum.electricunicycle.org/topic/20470-understanding-the-real-world-considerations-and-implications-of-speed-vs-torque-models/?tab=comments#comment-341032

[joku]

Maybe it's to give us full speed when the battery packs are at 10% of capacity. I hate the tilt back at 40% capacity.

Maybe it's for efficiency, since the speed is based on the average voltage of the pulses to the motor. With higher voltages, you can pulse less and achieve the same speeds.

Edited October 18, 2021 by joku

[Adel]

I wonder why they went to 126v instead of 118v. So far for every new generation of wheel voltage, EUC manufacturers  just added 4 cells in series to the battery packs.

67V= 16S

84V= 20S

100V = 24S

there were rumors at one point with Gotway experimenting with 118V = 28S but decided against it. KS seems to want to make the jump all the way to a 30S battery pack and bypass 118V option.

[Eucner]

From 67 V to 84 V is 25% more voltage. From 84 V to 100 V it is 20% more and from 100 V to 126 V 26% more. From 100 V to 118 V would have been only 17 % increase. The KS's chosen voltage step is well in line with previous steps.

[KAY GEE]

1 hour ago, Eucner said:

From 67 V to 84 V is 25% more voltage. From 84 V to 100 V it is 20% more and from 100 V to 126 V 26% more. From 100 V to 118 V would have been only 17 % increase. The KS's chosen voltage step is well in line with previous steps.

Well King Song never made a 100v wheel before and that's why some Riders are sceptical if they can pull it off.

[Eucner]

Yes, 126 V a 50% step for KS. 118 V would have been a 40% step. Either way I'm equally worried how they will accomplish.

[That Guy]

But what if they have just accomplished that? The prototype Jack was riding and currently the other one from the Indonesian supplier are extremely likely to be 126V… :-)

What can be engineered, can also be manufactured. After all the “jump” we are talking is not that huge, I mean not like High Voltage or thousands of Amps… :-)

[RayRay]

Maybe they decided to skip a step because they were worried that always being the last to adopt a higher voltage was hurting their brand. Although, I'm worried it's just about bragging rights; reminiscent of the "chip wars" of the early 2000's and the competition to produce the highest clock speed (Hz). 

 

Also, this strategy distracts from the top speed (kph) competition which KS has all but ceded.

Edited October 30, 2021 by RayRay

[Tawpie]

26 minutes ago, RayRay said:

the top speed (kph) competition which KS has all but ceded

Their CEO initially said something to the effect of "we'll never make a 30 mph wheel". Then came under marketing pressure and KS unwisely raised the advertised top speed of the 16X too close to the point where it wouldn't work (it didn't blow up, but it's not at all safe enough). I'm guessing that the V12 is pushing them to a 40 mph wheel and they're not eager to repeat the 16X safety misstep so they're designing in safety margin by going to 126V.

126V isn't a big step. It begs for better battery management, but the electronic parts are old and mature.

Edited October 20, 2021 by Tawpie

[Miko.cz]

On 10/14/2021 at 5:26 PM, RagingGrandpa said:

No!
100wh/kg.

Different strokes for different folks

just example of tons of wonderfull battery projects in last years without final market existence.