Li-ion cells cycle ageing

Batteries, Chargers, and Battery Management Systems.
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madin88   1 GW

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Re: Li-ion cells cycle ageing

Post by madin88 » Feb 07 2020 3:49am

Pajda wrote:
Feb 06 2020 2:10pm
The principle of this issue was already formally described in this topic. So yes HP cells have significantly worse cycle life than most HE cells under low loads up to ca 1-2C continuous discharge. Generally(Although I do not like generalizations) HP cells cycle life is almost independent of the load. That means that HP cells should be used only in applications which really needs HP cells. From my point of view there are three fundamental categories of the cells on the market if we take a cycle life into account.

HE cells (up to 1C continuous) M36, MJ1, GA, 35E
"BP" (balanced parameters) cells (up to 3C continuous) 29E, M29
HP cells (more than 3C continuous) 30Q, HG2, VTC6
I want to quote this since it so meaningful.
Many thanks Pajda :thumb:

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Re: Li-ion cells cycle ageing

Post by tolkaNo » Feb 07 2020 4:25am

Am i cucking myself by running 30q at 10a per cell then?

And if i was to use something like a 29e or m29, what discharge rate would give me the equivalent amount of voltage sag as my 30q's currently?

docware   1 kW

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Re: Li-ion cells cycle ageing

Post by docware » Feb 07 2020 4:23pm

Another charts delivery. Samsung 29E7 700 cycles, Samsung 30Q 407 cycles, LG MJ1 370 cycles, SONY VTC6 134 cycles, Samsung 50E 112 cycles, Samsung 35E 63 cycles.
Samsung 29E7  700 cycles.jpg
Samsung 29E7 700 cycles.jpg (203.24 KiB) Viewed 1970 times
Samsung 30Q   407 cycles.jpg
Samsung 30Q 407 cycles.jpg (197.71 KiB) Viewed 1970 times
LG MJ1   370 cycles.jpg
LG MJ1 370 cycles.jpg (195.99 KiB) Viewed 1970 times
SONY VTC6   134 cycles.jpg
SONY VTC6 134 cycles.jpg (193.56 KiB) Viewed 1970 times
Samsung 21700 50E   112 cycles.jpg
Samsung 21700 50E 112 cycles.jpg (212.8 KiB) Viewed 1970 times
Samsung 35E   63 cycles.jpg
Samsung 35E 63 cycles.jpg (192.05 KiB) Viewed 1970 times
Capacity decay comparison.jpg
Capacity decay comparison.jpg (177.6 KiB) Viewed 1970 times
Capacity decay comparison zoom.jpg
Capacity decay comparison zoom.jpg (186.07 KiB) Viewed 1970 times
DCIR comparison.jpg
DCIR comparison.jpg (154.51 KiB) Viewed 1970 times
Samsung 29E7 finished its goal 700 cycles with excellent DCIR result. 90,2 % of initial capacity is also very good result, especially if we realize that this cell cycled at 78,7 % DOD.
Measuring 4,2 – 2,5/1A discharge showed at 700 cycles 91,6 % of initial capacity and 91,6 % of initial energy.
Samsung 29E7 No5  1A comparison after 700 cycles.jpg
Samsung 29E7 No5 1A comparison after 700 cycles.jpg (194.04 KiB) Viewed 1970 times
DOD comparison.jpg
DOD comparison.jpg (99.02 KiB) Viewed 1970 times

john61ct   100 GW

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Re: Li-ion cells cycle ageing

Post by john61ct » Feb 07 2020 6:36pm

Very very valuable stuff

tolkaNo   100 W

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Re: Li-ion cells cycle ageing

Post by tolkaNo » Feb 08 2020 3:29am

Damn 30q is getting long in the tooth @ 400 cycles or so, closing in on 29e IR wise

Would be good to see HG2 also to find out which is the longest lasting out of the 30q/Vtc6/Hg2 trinity

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Re: Li-ion cells cycle ageing

Post by Dak77 » Feb 08 2020 3:41am

So 29E started with the highest available capacity at 4.1v -> 3.3v in relation to it's 4.2v initial capacity , and maintained almost no substantial dcIR rise throughout. Unless I'm looking at it wrong. Considering availability, cycle life, price, and low IR ; it seems really hard to beat . All that is left to wonder in the world, is a 5amp battle between M36, M29, and 29E . I guess the age old discussion about PF and GA being worthy contenders can be laid to rest. Adios Panny.

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Re: Li-ion cells cycle ageing

Post by Dak77 » Feb 08 2020 3:48am

tolkaNo wrote:
Feb 08 2020 3:29am
Damn 30q is getting long in the tooth @ 400 cycles or so, closing in on 29e IR wise

Would be good to see HG2 also to find out which is the longest lasting out of the 30q/Vtc6/Hg2 trinity
Honestly, it doesn't look that bad considering the current it can handle. I agree that I'd love to see HG2 vs 30Q head to head at 3C .

docware   1 kW

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Re: Li-ion cells cycle ageing

Post by docware » Feb 08 2020 4:45am

LG HG2 started yesterday with the same parameters as 30Q and VTC6.
LG HG2 No2.jpg
LG HG2 No2.jpg (208.86 KiB) Viewed 1905 times
LG HG2 DCIR.jpg
LG HG2 DCIR.jpg (170.69 KiB) Viewed 1905 times

Pajda   1 kW

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Re: Li-ion cells cycle ageing

Post by Pajda » Feb 08 2020 6:49am

docware wrote:
Feb 08 2020 4:45am
LG HG2 started yesterday with the same parameters as 30Q and VTC6.
Hmm... LG HG2 should have minimum initial capacity of 2950mAh. My samples was able to deliver this capacity even under 1C disharge rate.

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Re: Li-ion cells cycle ageing

Post by john61ct » Feb 08 2020 8:01am

Pajda wrote:
docware wrote:
Feb 08 2020 4:45am
LG HG2 started yesterday with the same parameters as 30Q and VTC6.
Hmm... LG HG2 should have minimum initial capacity of 2950mAh. My samples was able to deliver this capacity even under 1C disharge rate.
I find that "even" curious.

Lower the rate more mAh extracted right?

Or does an internal temperature rise / lowering resistance from higher rates result in higher capacity at higher C-rates?

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Re: Li-ion cells cycle ageing

Post by docware » Feb 08 2020 8:33am

LG HG2 No2 production date November 2017. Purchased fom nkon September 2018. In December 2018 capacity 2 909 mAh at 3 A discharge, measured at ZKETECH EBC-A10H.
In September 2019 measured with Maynuo M9712/ GW Instek GDM 8351 :
LG HG2 No2  September 2019.jpg
LG HG2 No2 September 2019.jpg (207.84 KiB) Viewed 1877 times
Storage at 3,5 - 3,7 V / 16 - 18 °C.

LG HG2 No1 measured 4.2.2020 :
LG HG2 No1 1A.jpg
LG HG2 No1 1A.jpg (189.43 KiB) Viewed 1877 times
Do you still think that calendary aging is not relevant ? Or some worse batch ?

john61ct   100 GW

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Re: Li-ion cells cycle ageing

Post by john61ct » Feb 08 2020 8:38am

I'm confused, what causes you to say it lost functional capacity in storage?

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Re: Li-ion cells cycle ageing

Post by amberwolf » Feb 09 2020 12:12am

look at the charts.

1a discharge on the pre-storage 2019 has higher capacity than the same on post-storage 2020, and capacity in text of post from 2018 was even higher, even though was tested at a 3x higher discharge.

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Re: Li-ion cells cycle ageing

Post by john61ct » Feb 09 2020 12:50am

Aha, you mean where it drops sharply justbefore hitting the X axis?

I just look at the point before that shoulder, like around 3.4V in this case.

Relying on coulometers rather than CC timing, and especially two different devices IMO could account for such tiny differences.

I would think the tests themselves would be a factor.

Were you suspecting calendar life in storage being a significant factor?

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Re: Li-ion cells cycle ageing

Post by amberwolf » Feb 09 2020 1:06am

just look at the charts.

they show end of discharge at a certain voltage at a certain drainage rate gives a certain amount of energy.

it's not about knees and bends and curves and whatnot, it's a simple end-of-line at a termination point, from a certain start point.

it's extremely clear.

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Re: Li-ion cells cycle ageing

Post by Pajda » Feb 09 2020 5:49am

docware wrote:
Feb 08 2020 8:33am
Do you still think that calendary aging is not relevant ? Or some worse batch ?
The only thing which I am saying again and again is to stop using generalization in the whole area of battery life classification. Each cell, even from another batch/revision of the same production model can have significantly different one or more parameters. We can definitelly find cells which will have still cca 90% of initial capacity after 10 years of storage in ideal conditions and then we can find another cell which will be almost dead after ca 5 years under the same conditions. Another thing is a time course of parameter fading in time. Some cells can show linear ageing curve, some will rapidly fade in the first years and then they almost stop with another parameter fading.

It all needs to be measured side by side and only then we can make relevant conclusion. Otherwise it ends with exactly the same myths like "30Q is the best cell ever made.., M36 must be a total shit because it is only rated as 5A discharge cell.., we all love Panasonic cells just because of Tesla.."

john61ct   100 GW

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Re: Li-ion cells cycle ageing

Post by john61ct » Feb 09 2020 6:36am

That is too bad, and not the case with other form factors and chemistries.


docware   1 kW

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Re: Li-ion cells cycle ageing

Post by docware » Feb 09 2020 7:35am

All my certainties about Li-ion cells are disappearing step by step, ….. :)
Thanks Pajda for sharing your experiencies.

Not only these HG2 issues, something strange happened to 50E and 35E testing channels. I contemplate if continue with those anomalous data, or finish them and start with new cells.
Samsung 35E anomaly.jpg
Samsung 35E anomaly.jpg (194.66 KiB) Viewed 1777 times
Samsung 50E  anomaly.jpg
Samsung 50E anomaly.jpg (252.97 KiB) Viewed 1777 times

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Re: Li-ion cells cycle ageing

Post by john61ct » Feb 09 2020 9:58am

I doubt that's the cell. Instrument glitch? sunspots?

docware   1 kW

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Re: Li-ion cells cycle ageing

Post by docware » Feb 09 2020 1:35pm

Yes, it´s very probably an instrument issue.

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Re: Li-ion cells cycle ageing

Post by flippy » Feb 11 2020 2:51am

i also get these sometimes. i just delete them from the file otherwise it messes up the average numbers.

doc, how do you impelement the IR on the table?
Lithium beats liquid dinosaurs.

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Re: Li-ion cells cycle ageing

Post by docware » Feb 11 2020 4:55am

flippy wrote:
Feb 11 2020 2:51am
doc, how do you impelement the IR on the table?
viewtopic.php?f=14&t=103092&p=1513811#p1513811

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Re: Li-ion cells cycle ageing

Post by docware » Feb 17 2020 11:52am

New batch of pictures : Samsung 30Q 472 cycles, LG MJ1 435 cycles, SONY VTC6 200 cycles, Samsung 21700 50E 165 cycles, Samsung 35E 125 cycles, LG HG2 64 cycles.

50E curve is obviously influenced by the ZKETECH failure.
Samsung 30Q   472 cycles.jpg
Samsung 30Q 472 cycles.jpg (198.98 KiB) Viewed 1538 times
LG MJ1   435 cycles.jpg
LG MJ1 435 cycles.jpg (196.96 KiB) Viewed 1538 times
SONY VTC6   200 cycles.jpg
SONY VTC6 200 cycles.jpg (191.73 KiB) Viewed 1538 times
Samsung 21700 50E   165 cycles.jpg
Samsung 21700 50E 165 cycles.jpg (214.22 KiB) Viewed 1538 times
Samsung 35E   125 cycles.jpg
Samsung 35E 125 cycles.jpg (192.62 KiB) Viewed 1538 times
LG HG2   64 cycles.jpg
LG HG2 64 cycles.jpg (191.95 KiB) Viewed 1538 times
Capacity decay comparison.jpg
Capacity decay comparison.jpg (179.2 KiB) Viewed 1538 times
Capacity decay comparison  zoom.jpg
Capacity decay comparison zoom.jpg (189.85 KiB) Viewed 1538 times
DCIR comparison.jpg
DCIR comparison.jpg (155.16 KiB) Viewed 1538 times

eMark   100 W

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Re: Li-ion cells cycle ageing

Post by eMark » Feb 17 2020 12:33pm

Pajda wrote:
Feb 09 2020 5:49am
The only thing which I am saying again and again is to stop using generalization in the whole area of battery life classification. Each cell, even from another batch/revision of the same production model can have significantly different one or more parameters. We can definitelly find cells which will have still cca 90% of initial capacity after 10 years of storage in ideal conditions and then we can find another cell which will be almost dead after ca 5 years under the same conditions. Another thing is a time course of parameter fading in time. Some cells can show linear ageing curve, some will rapidly fade in the first years and then they almost stop with another parameter fading.
Agree, but it's not just one as both PF and GA are disappointing.

Are PF and GA doing less than anticipated? Who's going to do a DIY build with these two stalwarts after their showing here? Does Pajda's post reflect what may be his and others disappointment with what we thought were two champions from Japan? Could that be one reason why it's rumored that Tesla Gigafactory is now using Samsung 21700 cells (50E?) to keep up with production demand ?

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Re: Li-ion cells cycle ageing

Post by john61ct » Feb 17 2020 12:51pm

Pretty sure their 21700 cell is not Samsung but the Sanyo / Panasonic NCR21700A,

apparently a 5Ah capacity version.

And they will be self-producing soon if not already

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