Li-ion cells cycle ageing

Batteries, Chargers, and Battery Management Systems.
goatman   100 kW

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Re: Li-ion cells cycle ageing

Post by goatman » Mar 05 2020 12:51pm

docware wrote:
Feb 28 2020 1:51am
Here is Samsung 30Q No 3 condition before the cycling :

viewtopic.php?f=14&t=103092&p=1513064#p1513064

Cycle No 1 had 2180 mAh, average at cycle 535 is 1880 mAh.
I find this interesting on whether to baby a 30q or not to baby it. if I look at the ah produced by the cell on your tests after 550 cycles, starting with 2180mah and now 1880 mah. take average mah 1980x 550 cycles, it has produced 1089 ah's

okashira 95% DOD at 7amp discharge/2amp charge started at 2800 mah and after 540 cycles was about 2100mah. average 2450mah x 540= 1323 ah's produced. also watt hours were 8wh at start and 6wh after 540 cycles. average 7wh x 540= 3787wh.

if im weed infesting let me know and ill stop after this post. if I average 20wh/km, that battery could have gave me 189.35kms so if I had a 20s10p pack/ 200 cells I would've been able to travel 37870 kms

after 700 cycles the average mah was 2375= 1662.5ah or 47587.9kms.

your cell so far is 1089ah or 31171.9kms travelled.

the pack is charged twice as fast and discharged 3 times faster.

I guess this is more like a race between a turtle and a rabbit, at 7 amps I could've travelled 37870 kms probably 4 times faster than 2amps for 31171kms, are you going to test the 30q to 700 cycles?

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Re: Li-ion cells cycle ageing

Post by Pajda » Mar 05 2020 3:44pm

docware wrote:
Mar 05 2020 11:21am
Pajda, could you please comment on my attempt ? Do your 50E tests have similar trend of the capacity ?
Continue with the test :) Yes I measured similar trend with my 50E samples. My closest settings is 4.1-3.2V at 0.5C-1C rate. The 50E cycle life is outstanding. Slightly better are only M36 and M29. Unexpectedly, the M50T cycle life is significantly worse, but on the other side M50T have lower 10s DCIR than 50E and it keeps it lower for the whole life.

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Re: Li-ion cells cycle ageing

Post by docware » Mar 05 2020 3:51pm

goatman wrote:
Mar 05 2020 12:51pm

if im weed infesting let me know and ill stop after this post.
I accept your suggestion, especially after reading your thread „100% discharge rate capacity“ , so thank you for no more posting here.

viewtopic.php?f=14&t=104568

Just few citates from ES members to your posts there :

LuboN : „I am sorry to inform You that You got it totally wrong. Please read some battery life related threads to get the basics right first.“
„…. I must say it is unbelievable how far can one misunderstandig go... Your problem is simple. You totally misunderstood and misrepresented the data in datasheet. You have no idea what it is about and for what.“

Ohbse : „Each time you clarify, it makes it significantly more confusing...“
„Completely, absolutely 100% wrong. This is my point - your fundamental understanding is utterly incorrect.“
„No, again, your graph is meaningless. The % figures you reference have ZERO bear“

Madin88 : „Sorry you are wrong“

Hillhater : „You Know... offering up a pile of regurgitated mess that has already been chewed over and spat out.... doesnt make it any more palatable the second time around !“

Ianhill : „Goatman are you electricgod playing a trick on John cuz surely No one can get it wrong this much.“

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Re: Li-ion cells cycle ageing

Post by docware » Mar 05 2020 3:56pm

Pajda wrote:
Mar 05 2020 3:44pm

..... Yes I measured similar trend with my 50E samples. My closest settings is 4.1-3.2V at 0.5C-1C rate. The 50E cycle life is outstanding. Slightly better are only M36 and M29. .........
Thank you Pajda.

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Re: Li-ion cells cycle ageing

Post by zacksc » Mar 06 2020 3:30pm

Does anyone have an idea where Samsung 40T cells might be in the cycle aging spectrum? I am thinking perhaps similar to the 30Q data shown above in docwares post.
And thanks very much, docware for sharing that awesome cycle aging data.

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Re: Li-ion cells cycle ageing

Post by Pajda » Mar 07 2020 3:39am

zacksc wrote:
Mar 06 2020 3:30pm
Does anyone have an idea where Samsung 40T cells might be in the cycle aging spectrum?
Yes we have

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zeccato   100 W

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Re: Li-ion cells cycle ageing

Post by zeccato » Mar 07 2020 9:06am

My question is: how much percentage of the new cells lose each year?
If I buy cells of 21700 5000mAh or 18650 3000mAh, and use them at 1c of continuous discharge.

for example: (I don't know how he treated them) one guy said:
a 10s4p battery consisting of cells LGDBMG118650, are 2850mAh with 10A discharge,
after about 4 years of non-intensive use, they now take only about 4000mAh.
Full susp. folding 20 swxh r. (2011),. 02 2020 MacT8. batt. 48v. 25A Life (2012), and 48 7,5A a123 (2018?). Controller programmable EB3 12 FET. Charger Balancer 14s: TP1430C. Gophert CPS-6011 60V 11A. Mercury (rarely). Buzzer. https://www.google.com/url?sa=t&source= ... 6dXxc9-lNW

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Re: Li-ion cells cycle ageing

Post by docware » Mar 08 2020 7:40am

I was curious about DCIR after 700 cycles through the whole SOC range. Initial DCIR measurement (green line) and after 700 cycles (yellow line) was done on different cells.

Conclusions:
- Panasonic PF DCIR is really very different from others cells
- the general shape of DCIR through SOC is confirmed for all 4 cells
- M36 and 29E7 are really excellent cells regarding DCIR
- it´s very difficult to properly determine SOC in the area 0 – 10 %

Panasonic PF No2 DCIR after 700 cycles.jpg
Panasonic PF No2 DCIR after 700 cycles.jpg (181.77 KiB) Viewed 1626 times
LG M36 No2 DCIR after 700 cycles.jpg
LG M36 No2 DCIR after 700 cycles.jpg (147.29 KiB) Viewed 1626 times
Sanyo GA No1 DCIR after 700 cycles.jpg
Sanyo GA No1 DCIR after 700 cycles.jpg (180.34 KiB) Viewed 1626 times
Samsung 29E7 No5 after 700 cycles.jpg
Samsung 29E7 No5 after 700 cycles.jpg (151.6 KiB) Viewed 1626 times

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Honk   100 W

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Re: Li-ion cells cycle ageing

Post by Honk » Mar 08 2020 2:59pm

Wow, extremely good and informative measurement.
I can't imagine how you manage all these tests in such short timeline.
Keep up the good work, it is so very great of you taking the time doing this.
Efficiency is king!

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Re: Li-ion cells cycle ageing

Post by john61ct » Mar 08 2020 3:50pm

Yes a tremendous service to us all, thank you

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Re: Li-ion cells cycle ageing

Post by hemo » Mar 08 2020 6:27pm

As John & Honk have said this really is fantastic testing by Docware, so kudos for the time consuming work being put in and aired here for all to view the results :bigthumb:.

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zeccato   100 W

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Re: Li-ion cells cycle ageing

Post by zeccato » Mar 09 2020 7:32am

Good test, but to be more real I'd like to know how many amps the new cells lose each year. (used normally).
Because if they lose more than 10% every year, I don't convert: I stay with my lifepo4 (8 years with 75-80%).
Full susp. folding 20 swxh r. (2011),. 02 2020 MacT8. batt. 48v. 25A Life (2012), and 48 7,5A a123 (2018?). Controller programmable EB3 12 FET. Charger Balancer 14s: TP1430C. Gophert CPS-6011 60V 11A. Mercury (rarely). Buzzer. https://www.google.com/url?sa=t&source= ... 6dXxc9-lNW

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Re: Li-ion cells cycle ageing

Post by john61ct » Mar 09 2020 8:50am

Not enough information, too many variables.

C-rate range, cycles per week, avg DoD%, charge profile, temperatures have a huge impact.

There is no "normal use". . .

But generally speaking everything else being equal, LFP lasts 4-8x longer

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zeccato   100 W

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Re: Li-ion cells cycle ageing

Post by zeccato » Mar 10 2020 2:44pm

zeccato wrote:
Mar 09 2020 7:32am
Good test, but to be more real I'd like to know how many amps the new cells lose each year. (used normally).
Because if they lose more than 10% every year, I don't convert: I stay with my lifepo4 (8 years with 75-80%).
is that right, do you think?
is it the same with the usual e-bike batteries?

(car) Lithium-ion battery degradation over time
Temperature 40% charge 100% charge

0 °C (32 °F)
40% charge: 2% loss after 1 year
100% charge: 6% loss after 1 year

25 °C (77 °F)
40% charge: 4% loss after 1 year
100% charge: 20% loss after 1 year

40 °C (104 °F)
40% charge: 15% loss after 1 year 100% charge: 35% loss after 1 year

60 °C (140 °F)
40% charge: 25% loss after 1 year 100% charge: 40% loss after 3 months

Batteries slowly lose their ability to store energy over time even when unused.
Full susp. folding 20 swxh r. (2011),. 02 2020 MacT8. batt. 48v. 25A Life (2012), and 48 7,5A a123 (2018?). Controller programmable EB3 12 FET. Charger Balancer 14s: TP1430C. Gophert CPS-6011 60V 11A. Mercury (rarely). Buzzer. https://www.google.com/url?sa=t&source= ... 6dXxc9-lNW

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Re: Li-ion cells cycle ageing

Post by john61ct » Mar 10 2020 6:47pm

Not all chemistries.

I have seen quality LFP cells lose less than 0.01% capacity stored cool and isolated well over a decade.

And cycled daily, average 80% DoD, but gentle C-rates, less than 5%, again over a decade.

LTO goes much **much** longer.

The chemistries selected for EV / propulsion for higher density

e.g LCO, LMO, NMC, NCA

may only go 300-500 cycles.

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Re: Li-ion cells cycle ageing

Post by Dak77 » Mar 11 2020 12:53am

Pajda (or anyone else with the data) , how does the M29 compare to 29E in DCIR at around 500 cycles at 2C discharge and .5C charge rate at 70% - 80% state of charge ? The reason I ask such a specific question is to get an idea about what kind of voltage sag one would expect at a 2C load . I'm close to ready to build a new pack with M29 , but I want to make sure 29E wouldn't be a better option. I'm not really asking for precise numbers as much as "are they in the same neighborhood" ?

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Re: Li-ion cells cycle ageing

Post by zeccato » Mar 12 2020 7:10am

john61ct wrote:
Mar 09 2020 8:50am
N................
If I were to take as an example: (LG INR21700-M50T 5000mAh - 7.3A) or (Samsung INR21700-50E 5000mAh - 10A) to make a battery of 15s 35Ah, and i use them with maximum discharge 1c, and charge 0.5c, 2 cycles per week, with winter temperature + 10-15  °C, and in summer +30-35  °C,
theoretically how many years will they last? or how many amps will they lose each year?
 
Thanks for all the suggestions.
Full susp. folding 20 swxh r. (2011),. 02 2020 MacT8. batt. 48v. 25A Life (2012), and 48 7,5A a123 (2018?). Controller programmable EB3 12 FET. Charger Balancer 14s: TP1430C. Gophert CPS-6011 60V 11A. Mercury (rarely). Buzzer. https://www.google.com/url?sa=t&source= ... 6dXxc9-lNW

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Re: Li-ion cells cycle ageing

Post by john61ct » Mar 12 2020 9:20am


zeccato wrote:theoretically how many years will they last? or how many amps will they lose each year?
Too many variables to predict specifically, IRL 500 cycles is a lot

The max 1C discharge / 0.5C charge rate is excellent, go slower or pre-warm in winter.

How many cycles per year?

Discharge to what avg DoD%, what charge profile?

What is avg ambient temperature?

All these factors have an impact, buy good cells for high energy use like the 50Es and do the best you can do.

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zeccato   100 W

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Re: Li-ion cells cycle ageing

Post by zeccato » Mar 12 2020 10:30am

Sorry about the translation but I didn't understand: IRL 500 cycles is a lot.
I don't need specifically, more or less.
100 cycles per year.
I'll discharge the battery at 1c, and i charge it at 0.5c.,
winter temperature + 10-15  °C, summer +30-35  °C,
john61ct wrote:
Mar 12 2020 9:20am
zeccato wrote:theoretically how many years will they last? or how many amps will they lose each year?
Too many variables to predict specifically, IRL 500 cycles is a lot

The max 1C discharge / 0.5C charge rate is excellent, go slower or pre-warm in winter.

How many cycles per year?

Discharge to what avg DoD%, what charge profile?

What is avg ambient temperature?

All these factors have an impact, buy good cells for high energy use like the 50Es and do the best you can do.
Full susp. folding 20 swxh r. (2011),. 02 2020 MacT8. batt. 48v. 25A Life (2012), and 48 7,5A a123 (2018?). Controller programmable EB3 12 FET. Charger Balancer 14s: TP1430C. Gophert CPS-6011 60V 11A. Mercury (rarely). Buzzer. https://www.google.com/url?sa=t&source= ... 6dXxc9-lNW

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Re: Li-ion cells cycle ageing

Post by john61ct » Mar 12 2020 1:38pm

Should last at least 5 years

IRL = "In real life"

as opposed to bench test data

This is my last post responding to this diversion, start a new thread if you like

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zeccato   100 W

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Re: Li-ion cells cycle ageing

Post by zeccato » Mar 13 2020 3:11am

Replies from another forum (translated):
But it's true that a 36V 10Ah loses something every year, and after three or four years you have to change it, but it's also true that if you make a 25Ah battery it will last long enough since it's not used like the classic 10Ah batteries.

If you want to have a LiIon battery that really lasts seven years, you will have to make a careful choice of cells to ensure that they are not stressed at all by the use and remember that they should never be discharged more than 80% of the maximum charge and in case of non-use should be "hibernated" to 50% of the charge and keep them in the lower part of the refrigerator, otherwise the hell you get what you want.

The LiIon batteries of electric cars are guaranteed for 1800 charging cycles and this thanks to some charging and discharging devices. they control the temperature etc. etc.
So if you make yourself a brand and first choice LiIon battery and then treat them very well as I have written above 500 cycles you double them great
Full susp. folding 20 swxh r. (2011),. 02 2020 MacT8. batt. 48v. 25A Life (2012), and 48 7,5A a123 (2018?). Controller programmable EB3 12 FET. Charger Balancer 14s: TP1430C. Gophert CPS-6011 60V 11A. Mercury (rarely). Buzzer. https://www.google.com/url?sa=t&source= ... 6dXxc9-lNW

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Re: Li-ion cells cycle ageing

Post by docware » Mar 13 2020 4:09am

hemo wrote:
Mar 08 2020 6:27pm
As John & Honk have said this really is fantastic testing by Docware, so kudos for the time consuming work being put in and aired here for all to view the results :bigthumb:.
Yes, DCIR mapping is quite time consuming. Curiosity was driving force here, as usually. I just, as others, share information which are interesting for all of us, hopefully. For that purpose was ES created, I believe.

New data : Samsung 30Q 636 cycles, LG MJ1 600 cycles, SONY VTC6 358 cycles, Samsung 50E 300 cycles, Samsung 35E 277 cycles, LG HG2 230 cycles.
Samsung 30Q   636 cycles.jpg
Samsung 30Q 636 cycles.jpg (202.12 KiB) Viewed 1240 times
LG MJ1   600 cycles.jpg
LG MJ1 600 cycles.jpg (201.32 KiB) Viewed 1240 times
SONY VTC6   358 cycles.jpg
SONY VTC6 358 cycles.jpg (196.87 KiB) Viewed 1240 times
Samsung 50E   300 cycles.jpg
Samsung 50E 300 cycles.jpg (216.6 KiB) Viewed 1240 times
Samsung 35E   277 cycles.jpg
Samsung 35E 277 cycles.jpg (196.61 KiB) Viewed 1240 times
LG HG2   230 cycles.jpg
LG HG2 230 cycles.jpg (194.46 KiB) Viewed 1240 times
Capacity decay comparison  zoom offset 13.3.2020.jpg
Capacity decay comparison zoom offset 13.3.2020.jpg (197.23 KiB) Viewed 1240 times
DCIR comparison 13.3.2020.jpg
DCIR comparison 13.3.2020.jpg (158.51 KiB) Viewed 1240 times

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flippy   1 MW

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Re: Li-ion cells cycle ageing

Post by flippy » Mar 13 2020 5:12am

what is your indication why the 30Q suck so much?
spec sheet wise it should behave better.
Lithium beats liquid dinosaurs.

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Re: Li-ion cells cycle ageing

Post by docware » Mar 13 2020 8:31am

flippy wrote:
Mar 13 2020 5:12am
what is your indication why the 30Q suck so much?
spec sheet wise it should behave better.
I have only this official 30Q specification. Do you have any other spec promising better lifetime ?
Samsung 30Q specification.jpg
Samsung 30Q specification.jpg (108.68 KiB) Viewed 1129 times

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Re: Li-ion cells cycle ageing

Post by Honk » Mar 15 2020 3:02am

From the chart it looks like 35E could be the new GA in terms of capacity decay.
I also wonder how a 18650 cell of LifePO4 would come out in tests like these.
It might reveal something we never thought of, or just imagined how it should behave by myth.
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