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US69

Fast charging the Kingsong 16X

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Posted (edited)

Split from the 16X thread.

On 8/5/2019 at 1:31 PM, Unventor said:

This is the basis of my question early in the thread. As far as I can tell the replies given about the KS16X 5A should be ok.

Note read on from the post I linked. You find more details why, how, and so on...

As from what I gathered @EcoDrift do not recommend 5A charging. I can only read their stuff through webtranslation as I don't read/write/speak  russian language.

Even when it is late...

Charging the 18XL or 16X (and even 18L) with 5 Amps is NO problem at all.

Charging a 6 parallel packs with 5 Amps means about 0,83 Amps per battery pack/cell...and a charge of 1,75 Amp per cell would still be 0,5C and considered low.

And Yes, the wiring can stand 5 Amps...no problem.

Edited by meepmeepmayer

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3 minutes ago, US69 said:

Even when it is late...

Charging the 18XL or 16X (and even 18L) with 5 Amps is NO problem at all.

Charging a 6 parallel packs with 5 Amps means about 0,83 Amps per battery pack/cell...and a charge of 1,75 Amp per cell would still be 0,5C and considered low.

And Yes, the wiring can stand 5 Amps...no problem.

How about 10A? 

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1 minute ago, chrisjunlee said:

How about 10A? 

the KS new wheels with the dual lenovo connectors can charge at total of 10A, 5 for each port.  

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6 minutes ago, eddiemoy said:

the KS new wheels with the dual lenovo connectors can charge at total of 10A, 5 for each port.  

I know - just wanted to get a recent signoff on this from a certain KS representative ;).

As for each port: I haven't checked my 16X, but to my understanding, they're simply wired in parallel. So 10A in one port should be fine (unless the connector and wiring to the board is somehow limited to 5A).

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8 minutes ago, US69 said:

I personally would NOT recommed it....

For ME...this is a bit to high....

This does not go with what other KS officials have said, and is my personal opinion.

Handling 18650 cells over 6 years now for vaping...charhing them up all time with over 0,5C...makes the lifetime significantly lower!

That might have no impact on lifespan of an EUC...but it does have on the cells.

My 2 cents...

I haven't worked out how the batteries are wired, but I agree 1C would be considered fast. To my understanding, a lot of the degradation is due to heat (resistance also goes up, producing even more heat), and better 18650 chargers will cool off the batteries.

What's the battery configuration for the 16X?

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9 minutes ago, chrisjunlee said:

I haven't worked out how the batteries are wired, but I agree 1C would be considered fast. To my understanding, a lot of the degradation is due to heat (resistance also goes up, producing even more heat), and better 18650 chargers will cool off the batteries.

What's the battery configuration for the 16X?

16X config is 20s6p in 2 times 20s3p.

But no, in our use cases „better chargers“ dont exist...as they cant „see“ the battery temperature.

You can have smart BMS...but thats not that easy when you more than on battery pack, as unfortunatly all our wheels have.

The only have passive BMS...so we should rely on standard charge values

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@chrisjunlee, You are leaving team 16X and joining team Gotway so why does it matter? :roflmao:

 

In other news your current mileage king now has his 5A charger from Ewheels so I should be able to knock out a 100 mile day here shortly. Only thing stopping me is my damn job and Burger Week here in Portland:

https://www.portlandmercury.com/events/burger-week

 

My one complaint on the Ewheels charger is the fan noise. Its pretty damn loud to run here in the office as I work in a shared area. I have a solution brewing with some high power fanless chargers. I'll post more as I build out the prototypes.

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So you have a job and manage to rack up that many miles a day, every day? :blink1:

And those things are loud, I can imagine. I have a 1200W PSU here for my LiPo charger and once you start charging at 15A it also makes a lot of noise. 5A at 84V = 420Watts. That heat has to go somewhere.

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Posted (edited)
1 hour ago, US69 said:

16X config is 20s6p in 2 times 20s3p.

But no, in our use cases „better chargers“ dont exist...as they cant „see“ the battery temperature.

You can have smart BMS...but thats not that easy when you more than on battery pack, as unfortunatly all our wheels have.

The only have passive BMS...so we should rely on standard charge values

So if I understand this correctly, the current would be distributed over 6 parallel. Or 1.7 A . That's a fast charge value I'm willing to accept. 

For those reading that don't have much experience with 18650 batteries, it's easy to reduce these discussions to black and white thinking, which become dogma without context.

FWIW, these are the conditions I would personally use, given the tradeoffs I've chosen:

  • slow charging: 1.5 A stock charger (1.5A / 6 = 0.25 A per cell. Incidentally, this is precisely the lowest most 18650 chargers go to)
    • use case: overnight, I don't need the wheel for the next 12+ hours
  • regular charging: 5.0 A rapid charger (5.0A / 6 = 0.83 A per cell, which is below the 1.0 A regular charging threshold)
    • use case: topping off at work, daily commuting 
  • fast charging: 10.0 A or two rapid chargers (10/6 = 1.67 A per cell. 2.0 A is considered fast, so 1.67 is a bit under that)
    • use case: those rare summer days when you need to charge between long epic rides

For posterity, the tradeoff is overall battery cycle life. The lower you stress the cells, the longer they last. But, charging is just one aspect of that: discharge rate is something I never see being discussed. What good is it to baby your batteries with a 0.25 A charge load, when you're ripping uphill pulling 10 A per cell?

Again, this is my just perspective, with the values and use cases I've chosen. I believe it is a reasonable set of choices to maximize your riding time, and thus your utility/enjoyment of your wheels.

Edited by chrisjunlee

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"2.0 A is considered fast"

That means absolutely nothing without knowing the size of the battery you are charging.

2.0 A on a 500mAh battery is extremely fast. 2.0A on a 22000mAh battery is extremely slow.

You need to addition all cells in parallel to know the exact battery size. With that value you can determine what's fast and slow.

Also I don't believe the cells are the limiting factor. It's the wiring and the electronics before we get to those cells. 

20S3P = 20 * 4.2 = 84V with 3 parallel packs to increase the capacity.

1554Wh = 84V * xA 

That means the battery is 18.5Ah. You can charge a 18,5Ah battery at 18A and it will still be considered a normal charge (since that's 1C). Charging at 10A still only is 0.5C.

I really don't see how you can damage the batteries by pushing 10A to them. I'm not talking about the wiring and all that is in front of that of course.

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12 minutes ago, chrisjunlee said:

posterity, the tradeoff is overall battery cycle life. The lower you stress the cells, the longer they last. But, charging is just one aspect of that: discharge rate is something I never see being discussed. What good is it to baby your batteries with a 0.25 A charge load, when you're ripping uphill pulling 10 A per cell?

On Point!

Thats why i am no fan of „extreme hill riding“ especially when these are longer -extreme- hills!

Thats a high amount of stress on your cells, and especially on a GW, which has no „overamperage“ protections, means even overdischarging, might damage your cells

 

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1 minute ago, US69 said:

On Point!

Thats why i am no fan of „extreme hill riding“ especially when these are longer -extreme- hills!

Thats a high amount of stress on your cells, and especially on a GW, which has no „overamperage“ protections, means even overdischarging, might damage your cells

 

That all depends on the charge.

If your battery is at 100% there will be no problem I think.

If your battery is at 30% you risk sagging it to the point of undervoltage when stressing it. 

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1 minute ago, ir_fuel said:

That all depends on the charge.

If your battery is at 100% there will be no problem I think.

If your battery is at 30% you risk sagging it to the point of undervoltage when stressing it. 

No, really not. what you mean is voltage drop....this is no problem on 100%...but on 30% you might be under the undervoltage limit.

But what i mean is max amp draw.

The cells are made for 10Amp draw continuous.

When going over that 10Amp rate, you damage the chemical structure of the cells.

Somthing that cant be seen...but really destroys the battery over middle/long term!

I am NOT saying that this is happening on each hill...but it CAN happen...

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Just now, US69 said:

No, really not. what you mean is voltage drop....this is no problem on 100%...but on 30% you might be under the undervoltage limit.

But what i mean is max amp draw.

The cells are made for 10Amp draw continuous.

When going over that 10Amp rate, you damage the chemical structure of the cells.

Somthing that cant be seen...but really destroys the battery over middle/long term!

I am NOT saying that this is happening on each hill...but it CAN happen...

Ah yes, the C rating of the battery pack.

The question is, how does a wheel handle this. Is this electronically limited and will it cut out, or will it just let you hammer those cells and either draw so much current stuff starts melting, or you are destroying your batteries.

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27 minutes ago, BleepBloopBlop said:

@chrisjunlee, You are leaving team 16X and joining team Gotway so why does it matter? :roflmao:

In other news your current mileage king now has his 5A charger from Ewheels so I should be able to knock out a 100 mile day here shortly.

As #2 with 214 miles, I guess that makes me the mileage Queen 👸

100 miles a day, averaging 20 mph is 5 hours of riding. 

Meanwhile, I can't find even find routes that let me average 20 mph. Either they're crowded with bicyclists, or they're 25 mph streets filled with cars going 35. 

I envy that Portland advantage.

32 minutes ago, BleepBloopBlop said:

My one complaint on the Ewheels charger is the fan noise. Its pretty damn loud to run here in the office as I work in a shared area. I have a solution brewing with some high power fanless chargers. I'll post more as I build out the prototypes.

Yeah it's pretty loud - I wish it was at least PWM temperature controlled.

Would love a fanless 10A charger, but it would be a stationary brick since the passive cooling on that thing would be monstrosity dissipating up to 840W of heat @50% efficiency.

A straightforward silent solution would be to parallel up X stock chargers. 4 stock chargers @1.5A = 6.0 A. It'll be unwieldly but silent. Not worth it unless you have them laying around already.

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Posted (edited)
16 minutes ago, ir_fuel said:

"2.0 A is considered fast"

That means absolutely nothing without knowing the size of the battery you are charging.

In this context, I thought it was clear I was talking about 18650 cells :)

Edited by chrisjunlee

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3 minutes ago, chrisjunlee said:

In this context, I thought it was clear I was talking about 18650 cells :)

That still doesn't say a thing. 3 cells in parallel can be charged 3 times as fast as 1 cell. Cells in parallel can be considered as one bigger cell. 

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16 minutes ago, ir_fuel said:

The question is, how does a wheel handle this. Is this electronically limited and will it cut out, or will it just let you hammer those cells and either draw so much current stuff starts melting, or you are destroying your batteries.

I hope the question is not, if the battery protection is more important as the drivers health. 

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1 minute ago, buell47 said:

I hope the question is not, if the battery protection is more important as the drivers health. 

If your board catches fire you'll crash anyway.

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20 minutes ago, ir_fuel said:

question is, how does a wheel handle this. Is this electronically limited and will it cut out, or will it just let you hammer those cells and either draw so much current stuff starts melting, or you are destroying your batteries.

KS has amp limits, that protect battery and board, in worst case by fuses. GW has no amp limit.

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9 minutes ago, ir_fuel said:

That still doesn't say a thing. 3 cells in parallel can be charged 3 times as fast as 1 cell. Cells in parallel can be considered as one bigger cell. 

As mentioned in my post, 0.25A per (18650) cell is slow. I've spelled out the calculations and mentioned the thresholds for normal and fast charging (18650s) as well. Those are my personal thresholds based on what I've seen 18650 charger set as their pre-sets.

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Posted (edited)
18 minutes ago, chrisjunlee said:

As mentioned in my post, 0.25A per (18650) cell is slow. I've spelled out the calculations and mentioned the thresholds for normal and fast charging (18650s) as well. Those are my personal thresholds based on what I've seen 18650 charger set as their pre-sets.

But your calculations do not make any sense. You are comparing a charger that loads 1 cell with a battery pack that contains a heap of cells in series and parallel. That's not how it works.

Edited by ir_fuel

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29 minutes ago, ir_fuel said:

But your calculations do not make any sense. You are comparing a charger that loads 1 cell with a battery pack that contains a heap of cells in series and parallel. That's not how it works.

Hmm, why not?

Assuming balanced 18650 cells. Let's say we have 20s1p (1 battery pack).

If we want to put a 1.0A charge, that would be a 84V charger @1.0A right? That's assuming this is being charged in series, which is the reason we need a 20S equivalent (84V) DC power source.

And again, assuming balanced cells and packs. If we have 2 battery packs, aka 20s2p: if we feed in 2.0 A, that should split evenly to 1.0A a pack.

Again, this is assuming we're charging in series. 

I know ideally we want to charge each cell individually, aka charging in parallel, with the assumption that cells are not perfectly balanced. Not sure why that's not the standard.

 

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Posted (edited)
6 minutes ago, chrisjunlee said:

Hmm, why not?

Because it does not work like that

Quote

Assuming balanced 18650 cells. Let's say we have 20s1p (1 battery pack).

 

Quote

If we want to put a 1.0A charge, that would be a 84V charger @1.0A right? That's assuming this is being charged in series, which is the reason we need a 20S equivalent (84V) DC power source.

And again, assuming balanced cells and packs. If we have 2 battery packs, aka 20s2p: if we feed in 2.0 A, that should split evenly to 1.0A a pack.

Again, this is assuming we're charging in series. 

I know ideally we want to charge each cell individually, aka charging in parallel, with the assumption that cells are not perfectly balanced. Not sure why that's not the standard.

 

Yes you are feeding 1A or 2A, but that doesn't say a thing about how "fast" or "slow" or "much" or "little" that is wrt to the cell/cells. To know that you need to take the capacity into account.

Imagine there exists such a thing as a 84V cell. If I feed that cell 1A and the cell has a capacity of 500mAh, that would be quite fast/heavy charging. If the cell has a capacity of 50000mAh then it would be very slow trickle charging.

Compare it to pouring water. If you pour water at certain rate in a small cup, it will splash and overflow. Now pour exactly the same rate in a huge bucket. You'll hardly notice it falling. 

Edited by ir_fuel

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