Cycle life tests of High Power density cylindrical cells

[Pajda]

How many sample cells are you using for testing each cell?

It depends, usually up to 10 samples, each with different cycle life test settings. I no longer do statistical evaluation of one test on multiple samples. Let's say that I have already seen something in the industry, so after the initial test, I put my experience to use. If I got very bad results, I try to get a sample from another supplier (very good results don't come out :wink: ). But that does not mean that I avoid problems.

I wouldn't mind donating and send some Samsung INR-21700 50G your way, if you'd be willing to add them to your list of tested cells. They boast about 80 % capacity after 1000 cycles. Might be interresting, no? PM me if you find it interresting .

Samsung 50G(1) is already running in the second thread here on ES (High Energy cell comparison). I have on my desk 50G2 version

 

[Sajeel]

I have on my desk 50G2 version

How do you tell 50G1 and 50G2 apart from each other?

 

[Pajda]

I have on my desk 50G2 version

How do you tell 50G1 and 50G2 apart from each other?

50G2 comes in tube with marking, there is also existing 50G6 version used in Rivian packs

 

[Pajda]

small update:

- Molicel P45B finally started its 5C torture test it was necessary to use different current path, which now bypassing the one in BF-2A fixture. As this cannot withstand more than 20A.
- Sony 18650VTC5A finished 1000 cycles with outstanding results. The huge difference can be seen in voltage drop chart after 1000 cycles (newly merged into one graph in third post of this thread)
- This week finally arrived Molicel P28B samples. Looking forward to seeing if it can beat the LG HJ2.

 

[Pajda]

small update after while:

LG HJ2 finished 1000cycles at 5C 100% DoD and it is definitely the best choice in this 3000 mAh category.
Tenpower 40TG started 5C 100% DoD cycle life test recently and shows a good potential.
Molicel P28B shows good results but I would definitely not classify it as a 2800 mAh cell. P26B marking would be much more fitting.

Tenpower 25PG will start cycle life test soon.

 

[riba2233]

small update after while:

LG HJ2 finished 1000cycles at 5C 100% DoD and it is definitely the best choice in this 3000 mAh category.
Tenpower 40TG started 5C 100% DoD cycle life test recently and shows a good potential.
Molicel P28B shows good results but I would definitely classify it as a 2800 mAh cell. P26B marking would be much more fitting.

Tenpower 25PG will start cycle life test soon.

Wow are you reading my mind?

I was just looking at 40TG the other day and it has some really good cycle numbers in the datasheet... Thank you so much for doing this!

 

[Souvlucky]

50G2 comes in tube with marking, there is also existing 50G6 version used in Rivian packs

Speaking of, here's a INR21700-50G6 cell:

 

[Pajda]

Speaking of, here's a INR21700-50G6 cell:

Is there link where to buy it?

 

[larsb]

"Standard Power Rate" test (1C continuous discharge)

note: the 1C discharge test is performed at ca 90% DoD (4.15V-3.00V)

Test eqiupment:
- 2pcs ZKETECH EBC-X0510
- BF-2A four-wire cell fixture (10A version with Nickel plated contacts)
- tested in room with relatively stable temperature 23 ±2 °C

Remarks and comments:
- someone considers these testers a child's toy
- the most problematic is tester accuracy. It is 0.2 % ±0.01 A. The stability is relatively good.
- do not much look at the absolute values, particularly at low currents in nominal capacity tests, trends are here important results.
- will try to add more data as it will come
- each 50th cycle is inserted datasheet nominal capacity test with 10s DCIR test (see dots in figure)
- minimal charging CV phase cut-off current is set to 100 mA due to the ZKETECH testers limitation
____
"Table" with values measured on precision battery tester (not ZKETECH). Those test were performed in temperature chamber under 25°C, TC is using forced air flow to maintan consistent temp. This 25°C air flow acts as cooling force on the cell surface, so the measured temperatures under high load will be affected by this.

added Samsung 30Q6 to the chart (X0510 tester), sample source: ---
added Sony 18650VTC6 to the chart (X0510 tester), sample source: NKON
added Samsung INR21700-40T3 to the chart (A20 tester), , sample source: NKON
added Samsung INR21700-50S(1) to the chart (A20 tester), sample source: NKON
added Molicel INR21700-P42A to the chart (X0510 tester), sample source: NKON
added Molicel INR21700-P45B to the chart (X0510 tester), sample source: NKON
added Molicel INR18650-HJ2 to the chart (X0510 tester), sample source: Vapcell
added Tenpower INR21700-40TG to the chart (X0510 tester), sample source: NKON
added Samsung INR21700-40T4 to the chart (A20 tester), , sample source: Vapcell

Beautiful data here, love it! You got a patreon?

It’d be interesting to see a degradation percent added to the table data for the cells ( ah, energy, dcir changes relative to new condition)

Impressive constant dcir over the cycles for the molicels!

 

[Pajda]

Small update.

I would like to add a graph to the note about cell surface temperatures.

____
"Table" with values measured on precision battery tester (not ZKETECH). Those test were performed in temperature chamber under 25°C, TC is using forced air flow to maintan consistent temp. This 25°C air flow acts as cooling force on the cell surface, so the measured temperatures under high load will be affected by this.

The sample is Molicel P45B after 1000 cycles at 5C dchg rate @ 100 %DoD. You can see how big impact have a forced air flow with 25°C temperature.

 

[EarlyAdopter]

The reason i mentioned six popular e-Power tools that use 1865s is that only the RIDGID e-Power battery that was examined used VTC6 3Ah cells (superior quality). The elite professionals that can afford to purchase RIDGID e-Power tools also expect long lasting performance. The other five e-Power tool manufacturers (including Milwaukee) could only afford to outfit their 1865 packs with the less expensive 25R 2.5Ah cells.

Other power tools manufacturers currently use or recently used VTC6 3Ah cells.

Makita uses them in their 18V LXT 6Ah battery packs.

Ryobi used them up until recently in their 18V 6Ah HP packs until switching over to EVE cells. I just shucked a year old bad Ryobi 6Ah HP pack and found Murata VTC6 cells.

This is great data Pajda. Thank you for collecting it.

 

[Pajda]

Finally added Molicel P30B results in the third post. I have to check once more cell temperature under 5C, in the table the measured value seems to be too good.

 

[riba2233]

wow P30B look unreal, IR is so low!

BTW what happened to tenpower 40TG? Did it die or is the test simply not finished? thanks!

 

[Pajda]

Thanks for asking, I have update the 21700@4000mAh graphs. Yes 40TG died. It was a sudden death, the 834 cycle pass ok and then 835 ends with zero voltage. The missing data between 550-650 cycle are caused by human error = the test ran normally, but I overwrote the resulting data twice in a row with other data, which pissed me off.

 

[riba2233]

Interesting, do you think it was a fluke or? I was really hoping that it would be a good candidate :|

 

[Pajda]

It's hard to evaluate these situations when the cell dies suddenly. I've seen it a few times. After all, for these cases it is good to follow proven methodologies such as running the test on multiple samples at once.

 

[riba2233]

Thanks, do you think you could maybe run another sample just to verify? This cell has really good specs on paper and is one of the most affordable so it might be worth it.

 

[Pajda]

Yes, I can run it again, it will only take 3-4 months to get to the same spot.

 

[riba2233]

That would be awesome, thank you so much

 

[Pajda]

I checked the stock today and unfortunately all the 40TG samples are used up, I will order new samples soon.

 

[riba2233]

Awesome, you are a savior

 

[funpony22]

Could you test the Lishen LR2170LA? Assuming that you can get your hands on some, of course.

 

[leffex]

Could you test the Lishen LR2170LA? Assuming that you can get your hands on some, of course.

I have them. LS LR2170LA cold as ice at my tester but then only 8 real Amps drain and some oddities. Voltage jumped too much when put into the charger, high ir, low capacity cell etcetera on a few cells of 30 used ones that I Had.

I think it may work with high amps. I bought for testing purpose only. I don't have history on them.

Capacity tested out from 3450-3675mah at max 0,5A liittokala 1A setting. If I would buy for a pack or build I would go for Samsung 40T or 50E or one of the newest 5500-6000mah?

Thanks for sharing information Pajda.