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KS18L - max. charging current


Seba

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On 8/24/2018 at 5:46 AM, US69 said:

I would advise not to go over 5 Amps, that goes for nearly all EUC available, reason is the wiring.

If you really want a faster charging then you Need to Change the wirings inside the Wheel.

5 Amps are About 420Watt per Hour...

Can you find out what the wire gauges used from the bms to the cells?  they that tiny that would cause issues charging at a mere 5 amps?  24 gauge wires would support 3.5amps.  Not worried about the Lenovo connector.   KS18L has 4p20s pack, 5amps split between the 4 packs would be 1.25 amps per pack.   24 gauge wire is the same wire in cat5/6 cable. Hard to believe that they would use such a small cable from the bms to the cells.  

If they use 28 gauge, would be borderline, 1.4 amps max

29 gauge would be insufficient, wires would melt, 1.2 amps max. 

KIng song would be able to provide the specs of the BMS wiring?  Or the max amps it can support when charging?

Edited by eddiemoy
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10 hours ago, eddiemoy said:

Can you find out what the wire gauges used from the bms to the cells?  they that tiny that would cause issues charging at a mere 5 amps?  24 gauge wires would support 3.5amps.  Not worried about the Lenovo connector.   KS18L has 4p20s pack, 5amps split between the 4 packs would be 1.25 amps per pack.   24 gauge wire is the same wire in cat5/6 cable. Hard to believe that they would use such a small cable from the bms to the cells.  

If they use 28 gauge, would be borderline, 1.4 amps max

29 gauge would be insufficient, wires would melt, 1.2 amps max. 

KIng song would be able to provide the specs of the BMS wiring?  Or the max amps it can support when charging?

As you heared...twchnically the 18L can go with 10Amps....

(i would not recommend that, 5 Amps is fairly enough)

Inside the Battery packs there is no „wire“ used!

The BMS connects to the cells by soldered nickel strips. 

As said: As long as you are on 5Amps you are good to go anytime!

Edited by US69
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20 minutes ago, US69 said:

As you heared...twchnically the 18L can go with 10Amps....

(i would not recommend that, 5 Amps is fairly enough)

Inside the Battery packs there is no „wire“ used!

The BMS connects to the cells by soldered nickel strips. 

As said: As long as you are on 5Amps you are good to go anytime!

When you think about it, 10A isn't all that much considering there are 4 packs.  it is just 2.5A per pack.  the nickle strips should be able to handle more than 2.5A.

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Just now, eddiemoy said:

When you think about it, 10A isn't all that much considering there are 4 packs.  it is just 2.5A per pack.  the nickle strips should be able to handle more than 2.5A.

Yes, sure the nickel steips do that...

Its just MY recommendation when i say i would not do that. a 2,5 Amp charge for a 3.500 cell is about 0,7 C...

This is slighlty over a 0,5 C Charge (would be 1,75 Amp)...so from my knowledge and experience with these 18660 cells on vaping i know that any over 0,5 C -slightly, a bit - goes on cost of longevity...

Just my opinion...

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3 minutes ago, US69 said:

Yes, sure the nickel steips do that...

Its just MY recommendation when i say i would not do that. a 2,5 Amp charge for a 3.500 cell is about 0,7 C...

This is slighlty over a 0,5 C Charge (would be 1,75 Amp)...so from my knowledge and experience with these 18660 cells on vaping i know that any over 0,5 C -slightly, a bit - goes on cost of longevity...

Just my opinion...

understood, funny thing about the C rating as Tesla motor's have been supercharging their 18650 cells for a while now without any issue.  But then again, they have active temperature management that allows them to charge at 2.2C for extended period of time.  I find that amazing!  I do understand it is different here with zero cooling, so playing it safe is good. 

Still 10A is much more than I expected and I'm guessing in the XL, the 10A is still the limit?  or would that be 15A limit for the XL.  @tinawong?  Is there a different max for the XL since it has 2 more packs for a total of 6 packs instead of the 4 that is in the L?

 

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1 minute ago, eddiemoy said:

understood, funny thing about the C rating as Tesla motor's have been supercharging their 18650 cells for a while now without any issue.  But then again, they have active temperature management that allows them to charge at 2.2C for extended period of time.  I find that amazing!  I do understand it is different here with zero cooling, so playing it safe is good. 

Still 10A is much more than I expected and I'm guessing in the XL, the 10A is still the limit?  or would that be 15A limit for the XL.  @tinawong?  Is there a different max for the XL since it has 2 more packs for a total of 6 packs instead of the 4 that is in the L?

 

Naah, 10Amp is the limit....

Isnt that enough? Thats allready a 800Watt charger which will allow you to charge a Xl in 2 hours....

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2 hours ago, US69 said:

Naah, 10Amp is the limit....

Isnt that enough? Thats allready a 800Watt charger which will allow you to charge a Xl in 2 hours....

But...my backyard nuclear power plant delivers 800k watt ??

fallout_4_nuclear_powered_locomotive_by_

When idling...

Edited by Unventor
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3 hours ago, eddiemoy said:

Still 10A is much more than I expected and I'm guessing in the XL, the 10A is still the limit?  or would that be 15A limit for the XL.  @tinawong?  Is there a different max for the XL since it has 2 more packs for a total of 6 packs instead of the 4 that is in the L?

I'm sure you all know this :-), but let's analyze - KS18L battery is configured as four paralell strings of twenty LG MJ1 cells of 4.2 V 3.5 Ah each - we call this configuration 20S4P. 20S gives us higher voltage (20 x 4.20 V = 84 V), 4P gives us higher capacity (4 x 3.5 Ah = 14 Ah) and charge/discharge current. As stated in LG MJ1 datasheet, standard charging current is 0.5 C, what translates to 7 A for whole battery. Maximum charging current is two times higher (1 C -> 14 A), but this may have negative impact on battery life. However for achieving declared battery life of 400 cycles, charging current should be set to 1.5 A per cell, what equals 6 A per whole battery. So it's safe to assume, that 6 A is a best compromise between battery life and charging time.

KS18XL battery have two more 20S cell strings and is built with Samsung E35 cells. So we have a 20S6P. Samsung E35 is also 3.5 Ah cell, but standard charging current is 1.7 A and cycle life optimized charging current is 1.02 A. This gives us 10.2 A as a standard charging current (just as @tinawong confirmed) and 6.12 A if you want to prolong your battery life.

Conclusion - regardless of wheel type, 6 A charging current may be considered fully safe for battery and its life, giving more than 1 hour of riding per 1 hour of charging. Of course, for overnight charging it's best to use smaller charging current, because it's beneficial to battery balancing process. As battery ages, balancing become more important. So it is best to have a charger regulated from 1 A to 6 A. And it's relatively easy to add voltage/current readout & adjustment to many fixed chargers, just like I did:

DSC01663.thumb.jpg.cf3d27ae7e0afb81e31edf4eb9896258.jpg

DSC01664.thumb.jpg.3eeae332717186900f226b545331845b.jpg

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11 hours ago, eddiemoy said:

understood, funny thing about the C rating as Tesla motor's have been supercharging their 18650 cells for a while now without any issue.  But then again, they have active temperature management that allows them to charge at 2.2C for extended period of time.  I find that amazing!  I do understand it is different here with zero cooling, so playing it safe is good. 

Still 10A is much more than I expected and I'm guessing in the XL, the 10A is still the limit?  or would that be 15A limit for the XL.  @tinawong?  Is there a different max for the XL since it has 2 more packs for a total of 6 packs instead of the 4 that is in the L?

 

18XL is with 10A limited as well. 

 

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8 minutes ago, jaiong said:

Any idea what's the 3rd blue (thinner) wire output from the battery pack is for? Measures zero volts with black.

If I remember correctly:

  • Black: Common negative.
  • Red: Discharge BMS positive port (power output).
  • Blue: Charge BMS positive port  (input from charger).
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On 8/25/2018 at 12:26 PM, andress said:

@esaj Actually KS 18L doesn't use GX16 but Lenovo connector. Do you happen to know what is the max amperage for those?

Monokoleso-Kingsong-KS-18L-18.JPG

If we would find this Lenovo Amps specification it is not relevant, because as we need only 2 wires, KS fortunately used both sides of connector plates (internal pin is not used at all). It is KS specific (IM V5 has the same Lenovo connector but one wire is connected to internal pin and it could be limitation factor there).

EA0972EA-659C-40C7-9111-5EB6E7B3A1C9.jpeg

Edited by jitesar
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On 11/1/2018 at 8:44 PM, Seba said:

I'm sure you all know this :-), but let's analyze - KS18L battery is configured as four paralell strings of twenty LG MJ1 cells of 4.2 V 3.5 Ah each - we call this configuration 20S4P. 20S gives us higher voltage (20 x 4.20 V = 84 V), 4P gives us higher capacity (4 x 3.5 Ah = 14 Ah) and charge/discharge current. As stated in LG MJ1 datasheet, standard charging current is 0.5 C, what translates to 7 A for whole battery. Maximum charging current is two times higher (1 C -> 14 A), but this may have negative impact on battery life. However for achieving declared battery life of 400 cycles, charging current should be set to 1.5 A per cell, what equals 6 A per whole battery. So it's safe to assume, that 6 A is a best compromise between battery life and charging time.

KS18XL battery have two more 20S cell strings and is built with Samsung E35 cells. So we have a 20S6P. Samsung E35 is also 3.5 Ah cell, but standard charging current is 1.7 A and cycle life optimized charging current is 1.02 A. This gives us 10.2 A as a standard charging current (just as @tinawong confirmed) and 6.12 A if you want to prolong your battery life.

Conclusion - regardless of wheel type, 6 A charging current may be considered fully safe for battery and its life, giving more than 1 hour of riding per 1 hour of charging. Of course, for overnight charging it's best to use smaller charging current, because it's beneficial to battery balancing process. As battery ages, balancing become more important. So it is best to have a charger regulated from 1 A to 6 A. And it's relatively easy to add voltage/current readout & adjustment to many fixed chargers, just like I did:

DSC01663.thumb.jpg.cf3d27ae7e0afb81e31edf4eb9896258.jpg

DSC01664.thumb.jpg.3eeae332717186900f226b545331845b.jpg

Hi,

that's what I'm looking for. 😊

Do you have the specs for me and some more informations and pictures? 

Where I can find this charger? The link is dead and I can't find it on there website. 

Greetings 

Frank 

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28 minutes ago, Seba said:

Next week I'll post some details for DIY-ers :)

That's sounds great. Please add the shopping list too. 😊

The 10 amp will fit perfectly my Inmotion V8 and the upcoming KS-16X 😁

Did you ordered it from China? 

Need quick a quick charger for my next vacation in 4 weeks. 😊

Due to Charge Doctor unavailability, a voltage regulation would be a nice option too. Did you think about it? 

Edited by buell47
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1 hour ago, buell47 said:

That's sounds great. Please add the shopping list too. 😊

Of course I'll add detailed part list with links to Mouser online shop.

1 hour ago, buell47 said:

Did you ordered it from China? 

No, I bought it here - https://batteryguru.eu/en_GB/p/Battery-charger-for-Li-ion-and-Li-poly-batteries-10A-20S-72V/62

1 hour ago, buell47 said:

Due to Charge Doctor unavailability, a voltage regulation would be a nice option too. Did you think about it?

I added voltage regulation to my previous charger (the silver one from the pics above). But in this version I intentionally resigned from this feature, as:

  1. it inhibits balancing process, which is especially important after few partial cycles of fast charging (typical situation when going for a longer ride),
  2. in my opinion it's much better to charge battery to full then immediately after go for a ride,after finishing store wheel without charging and charge it just before another ride.

Of course it is possible to add voltage regulation and it's not particularly hard to do.

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7 minutes ago, Seba said:
  • it inhibits balancing process, which is especially important after few partial cycles of fast charging (typical situation when going for a longer ride),
  • in my opinion it's much better to charge battery to full then immediately after go for a ride,after finishing store wheel without charging and charge it just before another ride.

I agree with you, that's exactly what I do with my R/C Lipo. 

But for my usual use within the week after the work it would be enough, if I can charge it slowly over night or on work to 80-90%. 

On the weekend I would charge to 100% (needed for longer trips), so around every 3th charge is with balancing. 

Maybe you can add a "how to" for voltage regulation too? 🙂

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On 5/24/2019 at 9:06 AM, buell47 said:

That's sounds great. Please add the shopping list too. 😊

The 10 amp will fit perfectly my Inmotion V8 and the upcoming KS-16X 😁

Did you ordered it from China? 

Need quick a quick charger for my next vacation in 4 weeks. 😊

Due to Charge Doctor unavailability, a voltage regulation would be a nice option too. Did you think about it? 

 

On 5/24/2019 at 8:43 AM, Seba said:

Next week I'll post some details for DIY-ers

Hi Seba, 

"next week" is long gone. :D

I know, there are more important things you have to do :)

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