Gotway's new 27100 battery cells

[Camenbert]

Calculating the volume of a 21700 cell, it's 51% bigger than a 18650.
As capacity and discharge are not more than 51% higher (5.000mAh 21700 = 3.300mAh 18650), I have doubt these use really different chemistry.

These 21700 are made by the same players (Samsung, LG, Sanyo etc..) and there is no noticeable difference when you compare the data-sheets
(for this, google the cell name + PDF, "NCR21700A" PDF for example)

[RagingGrandpa]

Gotway and Kingsong are using the LG M50T cell: 
https://www.dnkpower.com/wp-content/uploads/2019/02/LG-INR21700-M50-Datasheet.pdf

Max temp during use: 60°C (140°F) (above this, cells degrade quickly)
No explosions till 130°C (266°F)

Max discharge current: 7.3A (only!)

 

On 1/8/2020 at 2:33 PM, meepmeepmayer said:

Apparently there is basically no difference for the rider between the 18650 and 21700 cells they use. It's just easier (= cheaper) for Gotway to build packs with the bigger 21700 cells.

 

On 2/3/2020 at 3:16 AM, AtlasP said:

It's pretty obvious they're still just trying to push their underwhelming 21700-based refreshes because of the benefit to them (the manufacturer) even though there's no real benefit (and potentially some drawbacks) for actual riders/consumers.

 

 

[AtlasP]

36 minutes ago, RagingGrandpa said:

Gotway and Kingsong are using the LG M50T cell: 
https://www.dnkpower.com/wp-content/uploads/2019/02/LG-INR21700-M50-Datasheet.pdf

Can you provide a source for this? (Not doubting you, just trying to find sources.) So far I can only find official confirmation of this in the spec sheets for the MSX Pro, but not the Nikola+ or S18 (likewise I can't find any official confirmation on the V11's cells, either).

Edited April 12, 2020 by AtlasP

[RagingGrandpa]

12 minutes ago, AtlasP said:

Can you provide a source for this? (Not doubting you, just trying to find sources.) So far I can only find official confirmation of this in the spec sheets for the MSX Pro, but not the Nikola+ or S18 (likewise I can't find any confirmation on the V11's cells, either).

Fair- I'm going from MSP and S18 product descriptions.

https://www.ewheels.com/product/new-king-song-s18-1110wh-battery-2200w-motor-full-body-suspension-500-deposit/
"pack is configured in a 20S3P/60 cell configuration, using the LG M50T 5Ah 21700 format cells"

Love your spreadsheet btw, thanks for maintaining that

Edited April 12, 2020 by RagingGrandpa

[Camenbert]

49 minutes ago, RagingGrandpa said:

Gotway and Kingsong are using the LG M50T cell: 
https://www.dnkpower.com/wp-content/uploads/2019/02/LG-INR21700-M50-Datasheet.pdf

Max temp during use: 60°C (140°F) (above this, cells degrade quickly)
No explosions till 130°C (266°F)

Max discharge current: 7.3A (only!)

You link the M50 PDF from 2016, here is the M50T from 2018 https://www.batteryspace.com/prod-specs/11514.pdf

Yet no big difference, it claims 3C (15A) between 10° and 25° (page 7). That's 3200W in 3P 72Volt (aka 84V)
This LG cell look good for capacity, there are much better cell for power, like Samsung 40T.

 

 

[RagingGrandpa]

6 minutes ago, Camenbert said:

You link the M50 PDF from 2016, here is the M50T from 2018 https://www.batteryspace.com/prod-specs/11514.pdf

Aww that's bad news...

Max temp during use revised down from 60°C, now 55°C (131°F).
Max cycles revised down from 500, now 300 cycles to 80% capacity.

(FWIW, my MSX hits 130°F reported temp rather easily with steep slow offroad rides on cool 60°F days.)

[meepmeepmayer]

3 hours ago, AtlasP said:

Can you provide a source for this?

http://kebye.com/ (official Gotway website) list the battery cell type for many of their wheels.

[mrelwood]

 

9 hours ago, Camenbert said:

it claims 3C (15A) between 10° and 25°

Kingsong representative said 20A:

 

[Chriull]

39 minutes ago, mrelwood said:

 

Kingsong representative said 20A:

 

And the datasheet says ~7.xA _continous_ current.

The 20A are in the context of "the cell beeing capable"!

...this LG M50T would be capable of delivering even more...

In another datasheet of a LG INR21700 50T (https://asset.conrad.com/media10/add/160267/c1/-/en/002114679DS01/datenblatt-2114679-lg-chem-inr21700-50t-spezial-akku-21700-flat-top-li-ion-36-v-5000-mah.pdf)

there is no maximum continous current specified anymore. Just a max pulse power of 80W for 10 seconds at 80% state of charge. So a quite full cell can be burdened by specification for 10 seconds with 20 A.

... But that's the data for the 50T and not the M50T...

However for riding 50 km/h roughly something around 1400W motor output power is needed.  That's what 20s3p pack can deliver continously according to the datasheet. Even with not full cells and some losses between motor output and battery output.

But maximum battery current capability will be less than with the 20s6p configuration (i strongly assume ks16x still has a (slow) 30A fuse for each 2p block?). This would give a theoretical maximum of 20 cells*4.2V*90A~7.5kW. It's the question if this power is even possible with the motors torque over speed limit... (I've never seen limit estimation/graphs for these wheels).

My gut feeling is still that using some high current 21700 cell could give more capacity/performance although the "marketing capacity value" would show lower numbers?!

Maybe a new cell overheat alarm will be (have to be) introduced with the new 21700 cell wheels?

[AtlasP]

19 hours ago, meepmeepmayer said:

http://kebye.com/ (official Gotway website) list the battery cell type for many of their wheels.

I'm way ahead of you/unfortunately already all-too-familiar with that miserable site. ;-p Unfortunately they have an annoying habit of listing specs per each model category instead of per each specific configuration. Sometimes they will list multiple options separated by semicolons or slashes, but the number of for example weights or battery specs will differ from the number of battery configurations (so for example they'll list three battery configurations but only two weights or battery specs), with absolutely zero indication how the smaller list of items correlates to the larger list of items. Sometimes they indicate the specific battery make & model, but sometimes/often they only indicate the make and not the model. For speeds they list a "safe cruising speed" which is ridiculously low and a "no load speed" which is worthless (who cares how fast it could go with /no/ rider?), with no reasonable number between those. For range they give a single range of ranges for the entire set of battery configurations. Etc, etc. It's maddening.

To explore what I mean, check out my spreadsheet and see which Gotway wheels I don't have "MF" (manufacturer) speed or cell type or range or weight listed, then see the corresponding kebye.com page (linked already on my spreadsheet) and you tell me how I should map that mess to actual individual model+configurations--I dare ya. :-)

Edited April 13, 2020 by AtlasP

[meepmeepmayer]

4 hours ago, AtlasP said:

I dare ya. :-)

I'm way ahead of you: I won't even try