Li-ion cells cycle ageing
- Thread starter docware
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Tolkano
100 W
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?
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?
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 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 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.
Tolkano
100 W
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
Would be good to see HG2 also to find out which is the longest lasting out of the 30q/Vtc6/Hg2 trinity
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.
Pajda
10 kW
docware said:
Hmm... LG HG2 should have minimum initial capacity of 2950mAh. My samples was able to deliver this capacity even under 1C disharge rate.
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 :
Storage at 3,5 - 3,7 V / 16 - 18 °C.
LG HG2 No1 measured 4.2.2020 :
Do you still think that calendary aging is not relevant ? Or some worse batch ?
In September 2019 measured with Maynuo M9712/ GW Instek GDM 8351 :
Storage at 3,5 - 3,7 V / 16 - 18 °C.
LG HG2 No1 measured 4.2.2020 :
Do you still think that calendary aging is not relevant ? Or some worse batch ?
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.
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.
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?
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?
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.
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.
Pajda
10 kW
docware said:
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.."
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.
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.
eMark
100 kW
Agree, but it's not just one as both PF and GA are disappointing.Pajda said:
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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