Highest capacity 18650 cells

madin88 · Jul 30, 2018

Pajda said:
Yea I did, In one word the cycle life of Samsung 35E at 0.5C-1C 100% DoD is disaster. Unfortunatelly almost all Samsung 18650 and 21700 48G high energy cells have very bad cycle life at 100% DoD, Samsung 30Q have the same problem, only 29E and 25R shows satisfactory results. I should also noted that all above mentioned Samsung cells pass cycle life test under 0.5C-1C 50% DoD without problems, so under this particular test they are fully comparable to LG or Panasonic equivalents.
...
My guess is that Samsung 18650 cells suffers a lot even with 0.5C charge rate, which is standard(recomended) charge rate for most of LG and Panasonic cells and my measurements shows that they did not have problem with that. So I will start soon a new batch of test with 0.3C-1C 100% settings.

Thats very interesting. Looking forward for your findings / charts about the effect of charge rate.
I think, if mentioned Samsung cells pass the cylce life test at 0,5C-1C down to 50% DoD with success, than the main problem for the poor lifetime when discharged to 100% probabaly is not the charge rate but the low voltage cut off.

So, what was the cut off voltage?

Most cells are specified to 2,5V lvc, but i found out there is a huge difference between high power and high energy cells.
While a Samsung 30Q has almost no capacity left below around 3,2V (already >95% DoD), most high capacity cells have a lot more Ah left at this voltage an can be discharged to deeper voltage.
So it might make sense to differ between LVC cut off for each cell. Some types might suffer much more damage if discharged to 2,5V while other cells not so.

Pajda · Jul 30, 2018

madin88 said:
So, what was the cut off voltage?

Good question. If a have original datasheet I always follow recomended/nominal values. For Samsung 35E is datasheet available https://www.tme.eu/ro/Document/f9d93f9cb60fa6eb0a4caf9df5c96711/ACCU-INR18650-35E.pdf and so 0.5C is 1700mA, 1C is 3400mA and LVC is 2.65V.

You can read in datasheet that 0.5C is recomended standard charging current but not for cycle life! (sounds like oxymoron for me :lol: ) For cycle life is recomended 1.020mA which is exactly 0.3C. Samsung 30Q does not have this note in datasheet.

jumpjack · Jul 30, 2018

madin88 said:
So, what was the cut off voltage?

This issue just came out in another thread, so I created this image which joins two different discharge curves, comparing a samsung cell with an unknown cell from https://www.powerstream.com/lithium-phosphate-charge-voltage.htm :

https://jumpjack.wordpress.com/2018/07/28/tensioni-di-massima-e-minima-carica-batterie-al-litio/

Ivanovitch_k · Jul 30, 2018

Pajda said:
Yea I did, In one word the cycle life of Samsung 35E at 0.5C-1C 100% DoD is disaster.

edit: should've hit that refresh button, got severely toasted on that LVC thingy :lol:

sheeeii**** might explain why sammy says the cutoff voltage is 2.65V vs 2.5 for most other cells ?

Looking forward to your new results with less charge C.

In the meantime I will use caution and charge my 65-cell 35e pack at min "overnight-time fitting" C-rate... I'll also limit max DoD to ~25%...

flippy · Jul 30, 2018

Anything under 3v under load is killing cells.

Pajda · Jul 31, 2018

madin88 said:
While a Samsung 30Q has almost no capacity left below around 3,2V (already >95% DoD), most high capacity cells have a lot more Ah left at this voltage an can be discharged to deeper voltage.

From my measurement Samsung 30Q is on 93% DoD at 3V LVC and on 86% DoD at 3.2V LVC. In this particular parameter 30Q has almost same results as LG HG2.

jumpjack · Jul 31, 2018

If database on https://lygte-info.dk/ was public it would be possible to create a sparse chart showing various LVC values. Is there a method to access raw data?

madin88 · Jul 31, 2018

Pajda said:
From my measurement Samsung 30Q is on 93% DoD at 3V LVC and on 86% DoD at 3.2V LVC. In this particular parameter 30Q has almost same results as LG HG2.

Thank you for the exact values. Yes, when comparing the graphs from www.dampfakkus.de both 30Q and HG2 look identical.

Hillhater · Jul 31, 2018

jumpjack said:
If database on https://lygte-info.dk/ was public it would be possible to create a sparse chart showing various LVC values. Is there a method to access raw data?

?? All the data on lygte site is public accessable ?
But , im pretty sure they terminate all their 18650 etc Lithium tests at 2.8v by choice deliberately.

jumpjack · Aug 1, 2018

Hillhater said:
jumpjack said:

If database on https://lygte-info.dk/ was public it would be possible to create a sparse chart showing various LVC values. Is there a method to access raw data?

Click to expand...

?? All the data on lygte site is public accessable ?

I am talking of raw numbers, not charts.

Hillhater · Aug 1, 2018

But if the tests are only run to the same set cut off ..2.8v.. There wont be any raw data beyond that to work with.

sjd.aliyan · Aug 3, 2018

flippy said:
sjd.aliyan said:

Why 18650?
You can easily find high energy density prismatic cells.
18650 arnt most efficient in case of weight or volume

Click to expand...

Yes they are. With pouches you need heavy re-enforcement and you are stuck in having a fixed shape for starters. Second point is that pouches explode.

Seems like you already know everything.they why do you ask others?
Why do you ask a question when you dont like the answer.
Nobody uses 18650 for something serious other than tesla.theres a reason nobody likes 18650

flippy · Aug 3, 2018

sjd.aliyan said:
flippy said:

sjd.aliyan said:

Why 18650?
You can easily find high energy density prismatic cells.
18650 arnt most efficient in case of weight or volume

Click to expand...

Yes they are. With pouches you need heavy re-enforcement and you are stuck in having a fixed shape for starters. Second point is that pouches explode.

Click to expand...

Seems like you already know everything.they why do you ask others?
Why do you ask a question when you dont like the answer.
Nobody uses 18650 for something serious other than tesla.theres a reason nobody likes 18650

i am not asking a question.

and stating pouches are superior then 18650 is simply not true for mobile applications. there are many factors that sway in the favour of 18650's for (motor)bikes then pouches have.

ps: one of the many reasons why other companies dont use 18650's is simply production capacity. tesla owns the market on automoative 18650 production. they sell to BMW and other companies that also use their drivetrains.

the main reason why 18650's are superior is because you dont get a massive explosion/fire because a single 100Ah pouch goes thermonuclear and triggers the next pouch. 18650's dont have that issue. it's inherently safer. something i like when my junk and ass is 5 inches above it.

bigbore · Aug 3, 2018

sjd.aliyan said:
Nobody uses 18650 for something serious other than tesla.theres a reason nobody likes 18650

Are you sure?
I have been using 18650 with my Stealth Bomber capable of riding for many Km at about 90-100Km/h, then during night while sleeping I can charge it safely

Hillhater · Aug 3, 2018

flippy said:
the main reason why 18650's are superior is because you dont get a massive explosion/fire because a single 100Ah pouch goes thermonuclear and triggers the next pouch. 18650's dont have that issue. it's inherently safer.

Hmm ? Safer ?.... Like all those 18650 powered "hoverboards" that were banned after the batteries flared up and burnt down several houses .?

Ivanovitch_k · Aug 3, 2018

pouches or tubes, lithium batteries are dangerous and will go thermonuclear given the right circumstances.
That's a fact we have to deal with. And this is not the thread for that

Jil · Mar 21, 2019

zro-1 said:
I found the info here: http://lygte-info.dk/review/batteries2012/Common18650comparator.php to be very helpful. After you've selected the cells you'd like to compare, there is a link to read the full review of the cell. For example, here's a review of the LG MJ1 which I'm using in my packs.

From this website it appears that the Samsung INR18650-35E are indiscutably the best, with a real capacity (at 2A discharge) around 3300 mAh. Even the models branded "3600 mAh" doesn't match.
Do you know if there are some "real" 3500, 3600 or 3800 mAH 18650 out there ?

Hillhater · Mar 21, 2019

Jil said:
Do you know if there are some "real" 3500, 3600 or 3800 mAH 18650 out there ?

You have seen the Lygte site...and that has pretty much up to date on commercially available cells.
But, as you noted, even cells labled 3600 and above do not really have any more than 3300mah in typical use.
If you need more, you have to step up to the 21700 or 26650 format where genuine 5000mah cells are available.

hemo · Mar 22, 2019

Typically the max mah extracted from a cell is at a paltry 0.2a loading and is a figure I do not pay attention to.
For my use 3.2v is the min cut off cell voltage I use so base cell choice on this as my cut off and use the discharge graphs for my decisions depending on the amp draw, parallel cells in use and the range I want to achieve.

Highest capacity 18650 cells

madin88

10 MW

Pajda

10 kW

jumpjack

100 W

Ivanovitch_k

10 W

flippy

1 MW

Pajda

10 kW

jumpjack

100 W

madin88

10 MW

Hillhater

100 TW

jumpjack

100 W

Hillhater

100 TW

sjd.aliyan

1 mW

flippy

1 MW

bigbore

10 kW

Hillhater

100 TW

Ivanovitch_k

10 W

Jil

1 kW

Hillhater

100 TW

hemo

100 W

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