mass life cycle testing

[flippy]

The one i got costs almost 1000 euro with shipping and taxes.

Anything below that amount is basically junk.

 

[Taswegian]

Thanks for sharing your test data, is there a link to an index of results so far?
In various threads I've found googledocs links to individual results but couldn't figure out where to see an overview or complete list.

In particular I'm making some 2P packs for short trips close to home and I'm wondering what high discharge cells would do best with daily cycling like that.

25R maybe?

 

[flippy]

i am still finishing up the baseline tests, those thake a bit longer. that gives more perspective to the results i already have.

 

[DVDRW]

Exciting thread. 8)
I'm planning to do about the same. But DIY arduino tester controlled via PC software. Data logging to dropbox.
Software will look something like this:

Cells waiting:
Heter Lifepo4
LG ABB41865
LG GBMG11865 MG1
LG ICR18650-HE2
LG MJ1
Panasonic 18650PF
Panasonic NCR18650B
Samsung ICR18650-26H
Samsung ICR18650-26J
Samsung INR18650-13L
Samsung INR18650-25R
Samsung INR18650-29E
Samsung INR18650-35E
Sanyo NCR18650GA
Sanyo UR18650AA
Sony Konion US18650V3
Sony US18650FTC1 LFP
Sony US18650NC1

 

[flippy]

the 1.38A charge, 2.75 discharge (4.1-3V) run just completed on the 29E.
only lost ~200mAh over 500 cycles. but at this voltage range it only has 2200mAh to begin with so once i do the full voltage range test we can see how much the cell has lost.

 

[flippy]

so, here is some data:

the fluctuations you see is from the temperature changes in the room. i had to set the AC and heating about 8 degrees of space between them to prevent them working against each other and not kill the electric bill of my shop.
as this is a wear test and not a lab test so this does not invalidate the test unless you drive around in perfect 20c weather all day. in that case i want to know where you live and what the housing market is near you because i want to live there.


tests done with brand new samsung E29E7's.

benchmark cell: 4.2V~2.5V with 1.38A charge and 2.7A discharge:
note that i stopped at 450 cycles as i am moving my setup to a different workshop.

https://i.imgur.com/JChi55E.png

next up: the same but with 4.1~3V 500 cycles test:

https://i.imgur.com/D7fZlp8.png

next 500 cycles at the limit of 2.7A charge and 8.25A discharge at 4.1V and 3V:

https://i.imgur.com/mTLMZ8r.png

note that the high current tests are more even because they heat up a lot more.


so in the end the conclusion is pretty simple: as long as you keep under 4.1V and above 3V you can pretty much do whatever you want, cycling beyond those numbers does WAY more damage then running them hard does.

but as seen in the second test, if you baby them then they are pretty much indistructable.

this is bascially also how tesla gets away with their battery warranty, you need at least 1500 cycles or more to make a noticable dent in the capacity as they have way more concervative voltages (4.05 and 3.1V).

fun fact: when running the full range capacity thest the cells that had their full range used (the benchmark cell and the last high current cell) immedialty tanked to 3.8V under 0.8A load while the other cells only dropped to 4.05V.

 

[DjSpaceGhost]

That's pretty impressive stuff for a "2.7amp" battery. Would you expect a 50E to have comparable cycle life if kept under the same conditions?

 

[flippy]

That's pretty impressive stuff for a "2.7amp" battery. Would you expect a 50E to have comparable cycle life if kept under the same conditions?

No, high capacity cells have way less cycles in them. You can see this just on compairing datasheets.

 

[DjSpaceGhost]

That's pretty impressive stuff for a "2.7amp" battery. Would you expect a 50E to have comparable cycle life if kept under the same conditions?

No, high capacity cells have way less cycles in them. You can see this just on compairing datasheets.

:thumb: Thank you for the work you do and share (and everybody else that uses their personal time and money to do these tedious and time consuming tests) . I appreciate the advice I've been given so far on this forum.

 

[Majezan]

That's pretty impressive stuff for a "2.7amp" battery. Would you expect a 50E to have comparable cycle life if kept under the same conditions?

No, high capacity cells have way less cycles in them. You can see this just on compairing datasheets.

:thumb: Thank you for the work you do and share (and everybody else that uses their personal time and money to do these tedious and time consuming tests) . I appreciate the advice I've been given so far on this forum.

THIS! I am so impressed that someone in internet makes so much data for free, internet is beautiful, and you people are!

 

[Majezan]

so, here is some data:

the fluctuations you see is from the temperature changes in the room. i had to set the AC and heating about 8 degrees of space between them to prevent them working against each other and not kill the electric bill of my shop.
as this is a wear test and not a lab test so this does not invalidate the test unless you drive around in perfect 20c weather all day. in that case i want to know where you live and what the housing market is near you because i want to live there.


tests done with brand new samsung E29E7's.

benchmark cell: 4.2V~2.5V with 1.38A charge and 2.7A discharge:
note that i stopped at 450 cycles as i am moving my setup to a different workshop.

https://i.imgur.com/JChi55E.png

next up: the same but with 4.1~3V 500 cycles test:

https://i.imgur.com/D7fZlp8.png

next 500 cycles at the limit of 2.7A charge and 8.25A discharge at 4.1V and 3V:

https://i.imgur.com/mTLMZ8r.png

note that the high current tests are more even because they heat up a lot more.


so in the end the conclusion is pretty simple: as long as you keep under 4.1V and above 3V you can pretty much do whatever you want, cycling beyond those numbers does WAY more damage then running them hard does.

but as seen in the second test, if you baby them then they are pretty much indistructable.

this is bascially also how tesla gets away with their battery warranty, you need at least 1500 cycles or more to make a noticable dent in the capacity as they have way more concervative voltages (4.05 and 3.1V).

fun fact: when running the full range capacity thest the cells that had their full range used (the benchmark cell and the last high current cell) immedialty tanked to 3.8V under 0.8A load while the other cells only dropped to 4.05V.

Do you have those images not aviable?