KingSong 16X 1554Wh 2200W 16*3in (Released July 2019)

[Garrie Lim]

And finally to add on to this fast charging topic... 

We always worry about charging, but we forget that the battery also discharges.

If you look at your wheel app whilst riding, you will see the different amounts of amps being discharged as you ride.

We are so afraid to charge at 5A and yet we forget that our wheels are discharging at double digit figures constantly

[MaxLinux]

17 hours ago, Pengloong said:

I always connect charge cable to my turned off wheels first, then to the wall socket before switching on to charge. Have done the same for IPS,  Kingsong and Gotway wheels. Have never had any issue.....yet !!!!!

MSuper V2 sparks if connected this way. The charger must be plugged into wall socket before connecting to MSuper V2 in order to avoid spark. The King Song 18XL manual recommends connecting charger to wheel first, then connect charger to wall socket.

[bruno356]

1 hour ago, Garrie Lim said:

You are wrong unfortunately. 

KS16X is a 72V system.  20S6P

Yes you are right regarding full charge when we series cells together we increase voltage, hence 20 x4.2V =84.0V

However in this case where charging of batteries is the question, we need to look at the overall capacity of the whole system.  

When you parallel cells together, capacity(Ah) increases. Hence 6P: 6x3.5ah=21Ah

So you can think of the whole system as just one big cell that is 21ah. And as a general rule, standard charge is 0.5C

 

so 21/2=10.5

 

And we can safely say you can charge the whole system at 10amp/hr and it is still considered “standard” charging. Not fast charging. 

 

The only other question you have to ask is whether the wiring inside the wheel is able to handle the amount of amps you are pumping thru. The batteries may be able to handle 10amps and not break a sweat, but the wiring may not. 

@Garrie Lim my apologies your are obviously correct 20 cells in series only increases the total Voltage output not the amperage available.  Your calculation of the 10.5 amp max charging rate at 0.5C is correct - sorry for any confusion to others.

Regards - Bruno

[Garrie Lim]

16 minutes ago, bruno356 said:

@Garrie Lim my apologies your are obviously correct 20 cells in series only increases the total Voltage output not the amperage available.  Your calculation of the 10.5 amp max charging rate at 0.5C is correct - sorry for any confusion to others.

Regards - Bruno

No worries. I took a long time to learn about such stuff. I’m no expert myself. 

[DragonFZ]

I'm glad you guys are able to calculate voltage and amps... but

[Garrie Lim]

2 hours ago, DragonFZ said:

I'm glad you guys are able to calculate voltage and amps... but

What about it?

[Unventor]

1 hour ago, DragonFZ said:

I'm glad you guys are able to calculate voltage and amps... but

I understand what you mean. I am not sure I am best at explaining this, but here goes. 

Batteries have a working interval, looking at numbers above, the KS16X have 84V at top voltages, but as battery is discharge the voltage drops. It drops down to a point where you hit 72V. At that point you cannot discharge it further without chemical damaging the battery. As you charge it back up the voltage raises back to 84V this is the way to see it is fully charged.

Or that is the principle. I don't go into "correct" numbers as I am not 100% of specs and build of the KS16X, and I only uses my EUC in that sense I am nor a tech freaky on these. I can get very theoretical and loads of math involved. On the road it matters less to me. 

Only real thing you need to keep in mind is the power (watts) a motor can get is volt times amps , but since amps is more or less constant, the volts you can pull get lower as battery discharges.

This is important , because it means the motor cannot get as much power on close to empty battery, and if you try to pull too much power in accelerating fast of riding high speeds, the motor will not keep up or you can get a cut out. this result in loss of balance and you would normally end up on the ground. Another important thing is most EUCs generates power to battery when breaking or you hold back speed when going downhill. If battery is fully charged then it cannot dump this power anywhere, resulting in an overcharge cut out, end resulting loss of balance and likely you on the ground.

You can find more and others explaining the above in dynamics of EUC section. But since you are new here to the forum, I took this side topic here. 

If you like to discuss this more lets take this under the general section/thread.

[Garrie Lim]

2 minutes ago, Unventor said:

I understand what you mean. I am not sure I am best at explaining this, but here goes. 

Batteries have a working interval, looking at numbers above, the KS16X have 84V at top voltages, but as battery is discharge the voltage drops. It drops down to a point where you hit 72V. At that point you cannot discharge it further without chemical damaging the battery. As you charge it back up the voltage raises back to 84V this is the way to see it is fully charged.

Or that is the principle. I don't go into "correct" numbers as I am not 100% of specs and build of the KS16X, and I only uses my EUC in that sense I am nor a tech freaky on these. I can get very theoretical and loads of math involved. On the road it matters less to me. 

Only real thing you need to keep in mind is the power (watts) a motor can get is volt times amps , but since amps is more or less constant, the volts you can pull get lower as battery discharges.

This is important , because it means the motor cannot get as much power on close to empty battery, and if you try to pull too much power in accelerating fast of riding high speeds, the motor will not keep up or you can get a cut out. this result in loss of balance and you would normally end up on the ground. Another important thing is most EUCs generates power to battery when breaking or you hold back speed when going downhill. If battery is fully charged then it cannot dump this power anywhere, resulting in an overcharge cut out, end resulting loss of balance and likely you on the ground.

You can find more and others explaining the above in dynamics of EUC section. But since you are new here to the forum, I took this side topic here. 

If you like to discuss this more lets take this under the general section/thread.

I’m waiting for his reply. Because I know what he is trying to get at. 

[stephen]

30 minutes ago, Garrie Lim said:

What about it?

I think he means it says,,,,84.2v so does the wheel charge to 84.2v or just 84v

[Garrie Lim]

Just now, stephen said:

I think he means it says,,,,84.2v so does the wheel charge to 84.2v or just 84v

Ok let’s get to it then. Firstly the fact that he posted that as some sort of rebuttal just shows what he is intending to do. The picture isn’t even showing the latest 2200W motor(but nvm that’s besides the point)

There is no absolute figure for full charge or cut off. It is based on averages. 

It is generally accepted that 18650 cells cut off at 3.0V(safely, but can go down to 2.5V) and has a full charge of 4.2V. 

 

The reality though, is that cells rarely charge to 4.20V and hold their charge. The instant you remove it from its charger the voltage drops to 4.19/4.18/4.17..... you get the drift. 

 

Some cells might even slightly overcharge as well. In fact if you look at the data sheet of the MJ1 cell, the full charge is 4.2V +/- 0.05V

What you are seeing in the picture is pure marketing. The intention is to make something seem “more” than the competitor. 

 

The ks16x isn’t a 84V Wheel. It is a 72V Wheel. 

 

It isnt a 1600wh battery, it is a 1512wh battery

 

All these numbers dun really mean much unless you know what they are referring to and how they are derived. 

 

 

[esaj]

The general rule of thumb for battery capacities at least most manufacturers follows seems to be rounded nominal voltage times the amp hours of the pack. A "typical" Li-ion chemistry (excluding Li-titanate and LiFePo4) has a nominal voltage around 3.6-3.7V per cell, 4.2V full charge (I think some NMC's can go up to 4.3 or slightly beyond) and generally 3.0V as the "cut-off" voltage where the cell is regarded empty. 2.5V is a more critical threshold that should not be crossed to prevent cell damage. There are differences between different cell chemistries, off the top of my head I remember that NCA's have the highest energy density (highest capacity), but the lower capacity NMC's have higher discharge capability (lower internal resistance, less voltage drop and heat for the same amount of current vs. NCA, so higher output power can be used safely).

So the voltages of the wheels are as follows (using 3.7V nominal voltage, 4.2V full voltage and 3V "empty" voltage):

16S = 59.2V nominal / 67.2V full / 48V empty

20S = 74V nominal / 84V full / 60V empty

24S = 88.8V nominal / 100.8V full / 72V empty

It dependes on the wheel what the "empty" voltage is, some wheels drive the cells down to 3V, some stop at around 3.3V... some might even go lower. The "deeper" the discharge, the more the cell is "stressed" and the less (full) charge/discharge-cycles it can go through before starting to degrade faster. If you look at the above numbers, you notice that 3.7V isn't the "middle" between 3.0V and 4.2V, but the cell voltage doesn't drop linearly as it's discharged, it first drops fast, then more or less "plateaus" around the nominal voltage (still dropping, but slower) for the most of the discharge cycle, then drops faster again towards the end. Here's an example of a cell voltage as it's being discharged at constant current:

Do note that the above chart starts from around 4.3V, which sounds more like NMC (Nickel-manganese-cobalt, I think), and discharged further than is usually recommended. But the general idea still stands, the voltage drop is not linear across the discharge.

As for the capacities, for example "840Wh" KS16S has LG MJ1's as cells, these are 3500mAh NCA (Nickel-cobalt-aluminum, I think) Li-ion cells. There's 4 series of 16 cells  each in parallel (16S4P). Stacking cells in series raises the voltage, but not the capacity. Paralleled cells increase the capacity, but not the voltage. 16S = 59.2V nominal, 4 * 3.5Ah = 14Ah. 59.2V * 14Ah = 828.8Wh. The "840Wh" number comes from a rounded nominal voltage of 60V (rounded up from 59.2V), 14Ah * 60V = 840Wh. If you work the numbers on other wheels, you'll quickly notice that (at least on the 16S packs, haven't followed up on the newer wheels using 20S) pretty much every manufacturer uses the rounded 60V figure to calculate the watthour-capacity. Don't know if the 20S's use 74V, you can work out the math if you know the single cell capacity (in amphours) and the pack configuration (20SxP), at least there the nominal voltage is a "round" number of 74V, 24S might use 89V or 90V.

The real world numbers aren't as "cut-n-dry", as there are slight differences between the cells (like one nominal "3500mAh" cell might be 3475mAh, other one is 3525mAh), the characteristics change as the cells age (irreversable metal plating/stripping occurring on the cathode/anode, this is the main culprit behind the cells "aging"/"degrading" with use) and under different load (internal resistance of the cells) etc. Nothing in the "real world" physics and engineering is as "certain" as simplified math like this. On top of the "basic" chemistries (see for example https://lithiumhub.com/explaining-lithium-ion-chemistries/  for more details), there are "secret" additives different manufacturers use to enhance the properties of the cells, like slowing down plating etc.

Edited June 21, 2019 by esaj

[meepmeepmayer]

"84.2V" is simply an error. Should be "84V". Nothing more to it.

[DragonFZ]

Thank you... I read the marketing and thought it was an absolute. I really don't understand the math behind this, but I'm learning. If I cannot go by advertised Voltage, can I compare EUC by the estimated speed and range?

[meepmeepmayer]

2 minutes ago, DragonFZ said:

If I cannot go by advertised Voltage, can I compare EUC by the estimated speed and range?

Range is pure lies, too. It highly depends on the speed and rider. A nice rule of thumb is 1000Wh = 50km/30mi (for an ~80kg/180lbs rider at 30-35kph/19-22mph) which is 20Wh/km (33Wh/mi), and other battery capacities are proportional to that. Compare that to what the manufacturers advertise (60kg rider at 15kph is their excuse).

Speed is reliable info. Just don't confuse an absolute top speed at 100% battery with a normal riding speed over the course of a ride. E.g. Kingsong wheels with 50kph speed limit (like the 16X will presumably have) are not good if you actually wanted to ride 50kph. Because you'll constantly hit the alarm/tiltback then. Or a V8 (30kph top) is closer to a 25kph wheel in practice, because the top speed reduces with the battery charge. So remove 10%-20% from the top speed for a realistic speed that you'll actually safely ride with a given wheel.

By the way, ewheels charts are full of errors, don't put too much importance into some single number when comparing. Just ask here Real life experience is all that matters for EUCs anyways.

(You didn't mention it, but incline numbers are the most meaningless of them all. Ignore them completely.)

34 minutes ago, DragonFZ said:

I really don't understand the math behind this, but I'm learning.

Here's an example of battery math (for the 16X). The size of the 16X battery is

20 * 3.7V * 6 * 3500mAh = 74V * 21Ah = 1554Wh [= "1600Wh"]

[1 Ampere * 1 Volt = 1 Watt]

The battery pack is made of 6 blocks of 20 cells, the nominal ("average" from full to empty) voltage of a cell is 3.7V, and each cell has a capacity of 3500mAh. That gives a nominal voltage of the battery pack of 74V and a capacity of 21Ah. Multiply it to get the 1554Wh number for the battery size.

Arguments about this number are because people use different numbers. Is the nominal voltage of a cell 3.6V or 3.7V? Is the cell capacity 3500mAh or 3450mAh? (In the 16X case, it's 3500mAh cells, on Gotways, it is not.) Should we call this a 74V wheel (by nominal voltage of the battery) or a 84V wheel (by maximal voltage of the battery, which is 4.2V per cell, and 20*4.2V is 84V)? Is "1600Wh" lying or just some rounding for ease of use? Etc.

Doesn't really matter as long as everyone knows what is meant.

 

In the end, there's only 3 relevant voltages (with the exception of the Ninebot One Z): 67.2V (16*4.2V) which seems to be a thing of the past, 84V (20*4.2V), 100V (24*4.2V=100.8V). So there are no small differences there. It's one of those three.

Voltage isn't really good for comparing wheels anyways. It says very little on its own.

Battery packs also come in only a few different sizes (x blocks of y cells, where y defines the voltage of the wheel). Like 1600Wh (6*20), 1020Wh (4*20), etc.

[fryman]

You nerds are giving me a headache. 🤓

[eddiemoy]

I'm waiting for someone to explain internal resistance of the battery  which is inversely proportional to the amps drawn which results in a voltage dip when you are asking the wheel to do a lot resulting in a cut out. 

And also explain why 6 parallel packs are better and minimizing the chance of a cut out than 4 or 2 packs.  

LOL 

 

[erk1024]

@eddiemoy 

Just curious. Did you find the 16X to be more comfortable with the fatter tire, or about the same as the 18xl?

 

[eddiemoy]

33 minutes ago, erk1024 said:

@eddiemoy 

Just curious. Did you find the 16X to be more comfortable with the fatter tire, or about the same as the 18xl?

 

with the 20psi tire on the 16X, i found it pretty comparable to the 18XL, but more nimble, marginally less stable at higher speeds.  It absorbed bumps well.

[Garrie Lim]

3 hours ago, eddiemoy said:

I'm waiting for someone to explain internal resistance of the battery  which is inversely proportional to the amps drawn which results in a voltage dip when you are asking the wheel to do a lot resulting in a cut out. 

And also explain why 6 parallel packs are better and minimizing the chance of a cut out than 4 or 2 packs.  

LOL 

 

Controllers/Motherboards usually have an amp rating. The max amp they can draw.  Typically, it is ideal for your batteries to provide more amps than the controller can draw. 

It’s like a tap. You can control the amount of water that flows through it up to the max amount the pipe diameter allows. So it’s better to have more than enough water behind the tap compared to having less water, which means you aren’t able to get the max amount of water whenever you need it. 

 

Same goes for 18650 cells. Always take note of capacity(Ah) and discharge. 

 

The Mj1 cell has a max discharge of 10 amps.  Similarly to capacity, when you parallel cells together, the overall discharge increases. 

 

So for the ks16x with a 6P config. The max discharge you can get is 60amps, and I would assume most of our current 1600wh wheels use a 50amp controller. 

 

Hence if you lean too much and there isnt sufficient amps to compensate for your lean, it cuts. 

[Chriull]

8 hours ago, eddiemoy said:

I'm waiting for someone to explain internal resistance of the battery  which is inversely proportional to the amps drawn

No. The internal resistance is more or less constant. It raises with age/depreciation (permanently?) of the cells and by burdening (temporarily?) the cells.

Quote

which results in a voltage dip

With this resistance one gets a, to the current proportional voltage dip (U=R*I)

Quote

when you are asking the wheel to do a lot resulting in a cut out. 

An overlean ("cut out") happens once the motors back emv (generated voltage from the motor by turning the coils in the magnetic field) is equal (or higher) than the battery voltage -> then no current can flow anymore (current needs a voltage difference to flow) and once no current flows through the motor coils no torque is created anymore -> faceplant.

Quote

And also explain why 6 parallel packs are better and minimizing the chance of a cut out than 4 or 2 packs.  

A 6p pack has 1/6 of the internal resistance of a single cell, a 4p 1/4 and a 2p pack "only" half. So the voltage dips under load (current flowing) are 1/6, 1/4 or one half compare to one single cell.

So the voltage stays "longer" "higher" and it can "counter" more back-emv from the motor. So higher speeds and/or higher loads (burdens, peaks, potholes,...) are possible.

The higher "current availability" from 6 cells in parallel is nice but a secondary topic. (For comparing 8/6/4p packs more or less, a 2p pack will imo struggle and not be able to deliver the current "needed" from modern high power wheels)

 

Edited June 22, 2019 by Chriull

[esaj]

6 hours ago, Garrie Lim said:

The Mj1 cell has a max discharge of 10 amps.  Similarly to capacity, when you parallel cells together, the overall discharge increases. 

So for the ks16x with a 6P config. The max discharge you can get is 60amps, and I would assume most of our current 1600wh wheels use a 50amp controller. 

To be exact, the maximum safe discharge current the manufacturer recommends is 10A. In an unprotected cell, there's nothing but the internal resistance in the cell itself that limits this current, and if you short circuit such cell over a low enough resistance, you're going to get a hell of a lot more than 10A.

As an example, if the cell was fully charged to 4.2V and has an internal resistance of, say, 50mOhm (0.05ohm), and you'd short it with a wire and connections having same 50mOhm of resistance (likely it would be smaller, but to keep things simpler with more "round" numbers), the total resistance in the circuit is 100mOhm (0.1ohm). As a circuit, this is how it would look like:

The internal resistance of the cell and the external resistance of wiring/connections form a voltage divider.

The output voltage = 4.2V *  External_Resistance / (Internal_Resistance + External_Resistance) = 4.2V * 0.05ohm / (0.05ohm + 0.05ohm)  = 2.1V  (in general with a voltage divider, Vout = Vin * (low-side resistance) / (high-side + low-side resistance) ).

The voltage at the "Output_Voltage" would (in this case) be half of the internal voltage, 2.1V. Half of the voltage is lost over the cell internal resistance, heating up the cell.

How much current would you get out of this? With a 100mOhm of total resistance and 4.2V internal voltage, you'd get 42A running through the circuit. The power dissipation in the cell is the voltage drop caused by the internal resistance times the total current, 42A * 2.1V = 88.2W! That's a lot of power to burn into heat in a cell, and the reason why the manufacturer gives you the maximum "safe" continuous amperage. The cell can deliver much more current (in a real-world case, the connections and wire shorting the cell would likely have much lower resistance than 50mOhm, leading to much higher current, and even more losses inside the cell), but in the process, it will overheat and then catch fire or explode. However, it's possible to deliver higher than 10A in more short-lived spikes, in such case, the average current / power dissipation in the cell should be checked, and kept below the manufacturer recommended maximum for the cell to work reliably. Or rather, the cell temperature should be kept below the "critical" run-away thermal reaction temperature to prevent the cell from going up in flames.

In a wheel, you have more than one cell in series, so the total resistance is higher (amount of cells in series * single cell internal resistance). Also the internal resistances vary somewhat between individual cells and at least somewhat change (going a bit higher) over the lifetime of the cell. It is this internal resistance that causes the voltage to drop with current draw (and the cell to heat up), yet the voltage also drops during discharge as the cell charge is being depleted.

With more cell series in parallel, less current is needed to be drawn per series for the same amount of output current/power vs. single series, so the voltage won't drop as much.

In shorter spikes (fast acceleration, hill climbing), you're likely drawing several kilowatts from the batteries, at which point the currents can for a moment be very high, say that the voltage drops to 3.4V per cell for a 20S wheel with the current draw, for a total of 68V and 3kW is needed. How much current do you need at 68V to deliver 3000W? 3000W / 68V = 44A. Not that much of a problem for 6P, since each cell series needs to deliver "only" around 7.33A (44A / 6), but for a 4P system, it's already 11A per series (and the voltage would drop more due to higher current per cell-series). The 10A "limit" isn't a cut-n-dry -number, the cells won't immediately explode if you draw 10.01A, nor should it be assumed that it's totally safe to continuously draw 9.99A either.

Edited June 22, 2019 by esaj

[Afeez Kay]

So how many parallel packs does the z10 have 4p or 6p?

[houseofjob]

11 minutes ago, Afeez Kay said:

So how many parallel packs does the z10 have 4p or 6p?

Should be 14s6p using 3.2Ah LG MH1 cells

[Unventor]

Please let's go back the topic of KS16X 

[stephen]

10 minutes ago, Unventor said:

Please let's go back the topic of KS16X 

Ok then 😊

Kuji has modded his pads on his ks16x

https://www.instagram.com/p/By_rf6AHjHb/?igshid=184vxv0m3c7m6