Samsung 20S - high drain 18650 Li-ion cell's capacity test

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thunderheart   100 W

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Samsung 20S - high drain 18650 Li-ion cell's capacity test

Post by thunderheart » Jan 15 2019 7:31am

Hi guys! Samsung INR18650-20S is a 2000mAh Li-ion cell of 18650 size which supports continuous discharge at up to 30A.
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The battery was bought from my reliable supplier (Queen Battery) and tested with ZKETECH EBC-A20 and a self-made battery holder. It's a PC-connected battery tester supporting 4-wire measuring and discharging at up to 20A.
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I've used version 3.0 of my battery holder based on 0.5mm thick pure copper terminals
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I've followed all the prescriptions of the IEC61960-2003 standard concerning battery's capacity measurement. Before each discharging cycle each battery was charged at standard charge current mentioned in its datasheet to charge end voltage. Before each discharging or charging i've held a 1-1.5hrs pause. The environment temperature was 23.0-24.5°C. To be sure in results i've done each test minimum twice (usually 3-4 times).


Samsung INR18650-20S

The cell is marked as INR18650-20S SAMSUNG SDI 3 1IA1 which means that the production date is 01 Oct 2018.
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The main specs from Samsung 20S datasheet:
Capacity (min.): 2000mAh
Nominal voltage: 3.6V
Standard charge current: 1.0A (0.5C)
Rapid charge current: 4.0A (2C)
Charge cut-off current: 100mA (0.05C)
Charge end voltage: 4.20V
Max. cont. discharge current: 30A (15C)
Discharge cut-off voltage: 2.5V
AC impedance at 1KHz: ≤15mΩ
Max. weight: 48g

Measured initial DC IR at 2A in fully charged condition was 11±1mΩ

Measured weight of the tested cell was 46.25g
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Capacity test results:
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At 0.2C (or 0.40A) discharge Samsung 20S's capacity is 2165mAh - noticeably higher than the 2000mAh declared and it plays around 2000mAh all the way up to 20A but the energy, of course, decreases. Curves are flawless, without voltage drops and recovers.

Capacity tests showed that Samsung 20S is a great high drain cell and there is nothing to add.

Here is the video version of this review:
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Check out my YouTube channel for batteries, chargers and other stuff reviews.
I've launched my blog where you can find all my reviews in one place. Every new test/review will be first published on YouTube and in the blog. I'll be happy to see new subscribers, comments, suggestions and just your thoughts.
Yinlong LTO Lithium Titanate safety tests: https://youtu.be/eAUYbSDEy6I
Toshiba SCiB LTO Lithium Titanate safety tests:https://youtu.be/XsrRDZxEFQE

LG M50 vs Samsung 48G:https://youtu.be/KGJDogOG4zw
LiFePO4: QB26650 2500mAh 50A vs A123 ANR26650M1B: https://youtu.be/GOSkte11lRc

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SamRich   100 W

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Re: Samsung 20S - high drain 18650 Li-ion cell's capacity test

Post by SamRich » Feb 07 2019 2:22pm

Enjoying your reviews as I'm looking to build a new pack.
Looking for high current (10A per cell) and longevity (price is less of a concern) since I'm using for commuting.
This cell definitely has the performance but I'm concerned with the 60% at 250 cycle (15C) stated in the datasheet
I still have not found a better cell than the 30Q...

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Honk   100 W

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Re: Samsung 20S - high drain 18650 Li-ion cell's capacity test

Post by Honk » Feb 08 2019 10:39pm

SamRich wrote:
Feb 07 2019 2:22pm
Looking for high current (10A per cell) and longevity.
I still have not found a better cell than the 30Q...
30Q is not a great choice for longevity by cycle life.
https://endless-sphere.com/forums/viewt ... 6#p1433642
Quote: "its capacity drop is worse than almost everything comparable on the market."
Efficiency is king!

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thunderheart   100 W

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Re: Samsung 20S - high drain 18650 Li-ion cell's capacity test

Post by thunderheart » Feb 09 2019 5:52am

SamRich wrote:
Feb 07 2019 2:22pm
I still have not found a better cell than the 30Q...
It's one of the best and most beloved cells))
Yinlong LTO Lithium Titanate safety tests: https://youtu.be/eAUYbSDEy6I
Toshiba SCiB LTO Lithium Titanate safety tests:https://youtu.be/XsrRDZxEFQE

LG M50 vs Samsung 48G:https://youtu.be/KGJDogOG4zw
LiFePO4: QB26650 2500mAh 50A vs A123 ANR26650M1B: https://youtu.be/GOSkte11lRc

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Honk   100 W

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Re: Samsung 20S - high drain 18650 Li-ion cell's capacity test

Post by Honk » Feb 09 2019 8:47am

thunderheart wrote:
Feb 09 2019 5:52am
SamRich wrote:
Feb 07 2019 2:22pm
I still have not found a better cell than the 30Q...
It's one of the best and most beloved cells))
That may be so but it's not a great choice for cycle life.
Efficiency is king!

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SamRich   100 W

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Re: Samsung 20S - high drain 18650 Li-ion cell's capacity test

Post by SamRich » Feb 09 2019 11:42am

Honk wrote:
Feb 09 2019 8:47am
thunderheart wrote:
Feb 09 2019 5:52am
SamRich wrote:
Feb 07 2019 2:22pm
I still have not found a better cell than the 30Q...
It's one of the best and most beloved cells))
That may be so but it's not a great choice for cycle life.
The specs state ~75% DOD after 300 cycles but that at 4A charge an 15A Discharge (4.2V to 2.5V) - which is crazy!

I'm certain you could get way more cycle to 75% capacity if you charged only up to to 4.0-4.1V and discharged to 3.3V (that would still give you more than 2Ah) while keeping the discharge below 8A.

I'd really like to see the cycle life test for the 30Q under those less stressful conditions, say 4V-3.3V at 1A charge 5A discharge. I don't have a rig to do that...maybe some Arduino based setup would be pretty easy to build?

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Honk   100 W

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Re: Samsung 20S - high drain 18650 Li-ion cell's capacity test

Post by Honk » Feb 09 2019 12:35pm

@SamRich

Maybe you should read the info about 30Q I posted earlier!
https://endless-sphere.com/forums/viewt ... 6#p1433642
Efficiency is king!

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SamRich   100 W

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Re: Samsung 20S - high drain 18650 Li-ion cell's capacity test

Post by SamRich » Feb 09 2019 12:41pm

Honk wrote:
Feb 09 2019 12:35pm
@SamRich

Maybe you should read the info about 30Q I posted earlier!
https://endless-sphere.com/forums/viewt ... 6#p1433642
I did, but how do you support those claims? Do you have any data or references?

999zip999   100 GW

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Re: Samsung 20S - high drain 18650 Li-ion cell's capacity test

Post by 999zip999 » Feb 09 2019 1:15pm

Honk what is your favorite cell ?

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Honk   100 W

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Re: Samsung 20S - high drain 18650 Li-ion cell's capacity test

Post by Honk » Feb 09 2019 1:17pm

@SamRich
I can't support any claims myself.
Ask user Pajda who has performed the tests on 30Q and a lot of other cells as well.
Efficiency is king!

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Honk   100 W

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Re: Samsung 20S - high drain 18650 Li-ion cell's capacity test

Post by Honk » Feb 09 2019 1:20pm

999zip999 wrote:
Feb 09 2019 1:15pm
Honk what is your favorite cell ?
My favorite is Samsung 29E as it gives you the best bang for the buck and it is proven longlife as well.

Just to clarify, the 29E is NCM chemistry and not NCA as stated by many due to false information when the cell was brand new to the market.
http://cdn14.21dianyuan.com/download.php?id=238880
productdescriptionofbatteryNCR18650-29E.zip
Chemistry NCM
(281.31 KiB) Downloaded 15 times
Efficiency is king!

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SamRich   100 W

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Re: Samsung 20S - high drain 18650 Li-ion cell's capacity test

Post by SamRich » Feb 09 2019 3:57pm

Honk wrote:
Feb 09 2019 1:20pm
999zip999 wrote:
Feb 09 2019 1:15pm
Honk what is your favorite cell ?
My favorite is Samsung 29E as it gives you the best bang for the buck and it is proven longlife as well.

Just to clarify, the 29E is NCM chemistry and not NCA as stated by many due to false information when the cell was brand new to the market.
http://cdn14.21dianyuan.com/download.php?id=238880

productdescriptionofbatteryNCR18650-29E.zip
Yeah I'm debating between 29E, 30Q and 35E. (sorry should move conversation to 30Q page...)
To me this is why I need the the 30Q over the 29E - I need 7A per cells peak and there is just too much sag with the "E"
From https://lygte-info.dk/review/batteries2 ... arator.php
Image

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Honk   100 W

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Re: Samsung 20S - high drain 18650 Li-ion cell's capacity test

Post by Honk » Feb 09 2019 7:02pm

Can't argue with that at heavy 7 amps load.
But the difference is just 0.2V at 7amps.

At my case I take it easy on the cell stress.
In average I run 29E at 1.5amps/cell and at these levels the sag difference vs 30Q is only 0.1V.
This is just to small for me to look for other and presumably more expensive cells.
Each of my 1kWh packs only cost $220.
Efficiency is king!

Pajda   100 W

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Re: Samsung 20S - high drain 18650 Li-ion cell's capacity test

Post by Pajda » Feb 10 2019 4:24pm

High power/drain cells like 30Q, HG2 or VTC6 are usually not the optimal choice for the "standart traction" application. If you look at e-bike batteries from Bosch or others, they are today in 400-500Wh range for 250W rated motors (they can do ca 500W peaks for couple of seconds and so you are at 1C maximum dchg rate) but the average is 0.5C max or lower. Also e-bikes today are charged very slowly, 0.3C charge rate is still considered as fast charging. So they use cheap cells like 29E, or very favored today is LG MH1. High-end e-bike batteries are using mostly MJ1 (but GA and even 35E works in e-bike batteries also without significant problems).

In fact all above mentioned high power/drain batteries have worse cycle life at low C rates (up to 1C) than most of high energy cells on the market. And this is valid for 21700 size as well. High energy Samsung 40T has far worse cycle life at 1C discharge rate than the high energy model 50E.

However if you are convinced that you really need >2-3C average cells, then there is not many better options than choosing high power cells like 30Q or 40T.

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thunderheart   100 W

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Re: Samsung 20S - high drain 18650 Li-ion cell's capacity test

Post by thunderheart » Feb 10 2019 5:31pm

Pajda wrote:
Feb 10 2019 4:24pm
High energy Samsung 40T has far worse cycle life at 1C discharge rate than the high energy model 50E.
Based upon your tests or datasheets?
Yinlong LTO Lithium Titanate safety tests: https://youtu.be/eAUYbSDEy6I
Toshiba SCiB LTO Lithium Titanate safety tests:https://youtu.be/XsrRDZxEFQE

LG M50 vs Samsung 48G:https://youtu.be/KGJDogOG4zw
LiFePO4: QB26650 2500mAh 50A vs A123 ANR26650M1B: https://youtu.be/GOSkte11lRc

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SamRich   100 W

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Re: Samsung 20S - high drain 18650 Li-ion cell's capacity test

Post by SamRich » Feb 10 2019 8:46pm

thunderheart wrote:
Feb 10 2019 5:31pm
Pajda wrote:
Feb 10 2019 4:24pm
High energy Samsung 40T has far worse cycle life at 1C discharge rate than the high energy model 50E.
Based upon your tests or datasheets?
So to your point...if I could build either a 30Q 13P (39Ah), 35E 13P (45Ah), 40T 9P (36Ah) or 50E 9P (45Ah) pack that would run at 50A avg and 100A peak and would charge to only 4V (I only need 15Ah between charges)

What would you recommend for cycle life?

Appreciate your input.

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