New eve different from old eve

[jtvt]

I finally got my other two strings hooked up.

I have 32 cells from Basen (Emily) from around Feb and 32 from Qishou (Amy) from around May. The posts are not in the same place. The posts on the newer cells are farther apart. Both have "eye" shape posts and qr codes match eve. It doesn't matter for me since they are in separate strings, but that might cause problems for others.

I think it's been brought up before, but I wonder if the Quishou Amy is Luyuan Amy. I was sent photos, etc and the packaging was the same including corner protectors for the new cells. Studs were welded. Date codes are end of April. So far cell voltages haven't diverged at all.

Anyway, so now I have 32 cells with welded studs and 32 cells without. So it will be interesting to see if the banks diverge. So far, it hasn't seemed to matter. I did have one issue where a couple threads of one cell stripped out of one of the older cells. The stud wasn't all the way in. So far, I was able to thread a new stud in using the rest of the threads and it's holding.

My procedure for adding new strings was:
1) top balanced the new cells
2) charge old strings to float via normal charge controller
3) take offline the old strings
4) put online the new strings
5) discharge new strings 10%
6) charge new strings to float via normal charge controller
7) shutoff loads and charging
8) wait for new strings to settle so voltage was close across strings (it was .05 off)
9) put online old strings
10) turn on loads and charging
11) At this point the old strings cell voltages were not as flat as the new cells. So I ran an extra long absorb which means an extra long balance. The cells delta came to .01v

 

[Steve_S]

Studs are less prone to "thread issues" and are great for proper torquing. If the Tapped & Screwed cells are properly torqued and all the little rules are done, you won't have any other issues.

EVE has not stopped producing the N Series and replaced them with the K Series (slightly bigger), 6000 Cycle as opposed to 3000.

 

[Stepandwolf]

Studs are less prone to "thread issues" and are great for proper torquing. If the Tapped & Screwed cells are properly torqued and all the little rules are done, you won't have any other issues.

EVE has not stopped producing the N Series and replaced them with the K Series (slightly bigger), 6000 Cycle as opposed to 3000.

Amy from Luyuan said N production stopped in August. However, the life cycle difference isn't as you suggest. This is from Basen and confirmed by a user here, I think named Randy.

"The cycle life of K and N is actually the same. K has 6000 cycles, but it is based on 0.5C discharge, and N has 3500 cycles are based on 1C discharge"

 

[Bob B]

"The cycle life of K and N is actually the same. K has 6000 cycles, but it is based on 0.5C discharge, and N has 3500 cycles are based on 1C discharge"

The suggestion that just because they used a different criteria in their spec sheet ..... that that is the only difference is ridiculous.

 

[MrPhoton]

Amy from Luyuan said N production stopped in August. However, the life cycle difference isn't as you suggest. This is from Basen and confirmed by a user here, I think named Randy.

"The cycle life of K and N is actually the same. K has 6000 cycles, but it is based on 0.5C discharge, and N has 3500 cycles are based on 1C discharge"

Amy from Luyuan told me about the LF280K about 60 days ago:

"Wan Amy:
LF280K,6000 cycles, it is only needed in special fields, what we sell is LF280N"

Attaching JPG of chat session.....

Does this add up?

 

[RobertGreen]

The suggestion that just because they used a different criteria in their spec sheet ..... that that is the only difference is ridiculous.

I think trying to take these life cycle figures at face value and with 100% confidence doesn't make sense. The spec sheet for the "K" models says that their testing regimen is that they fully charge and then discharge the cells at 0.5c, meaning that they can only run 6 charge and discharge cycles in a 24 hour period. In other words, it would take 1000 days to run through the claimed 6000 cycles.
Have the "K"s even been manufactured and able to be tested for more than 1000 days?

It seems that we don't have much good information to go on here, but I find the idea that they all of a sudden made a mysterious change to the fundamental chemistry or construction of these cells that resulted in the lifecycles almost doubling to be pretty farfetched as well.

I'd like to hear what EVE or anyone with any actual knowledge of how this chemistry/tech works might say about this apparent huge leap in cell life expectancy.
And what magnitude of a difference would you expect to see by changing the testing regimen from 1c to 0.5c?

 

[Bob B]

I think trying to take these life cycle figures at face value and with 100% confidence doesn't make sense. The spec sheet for the "K" models says that their testing regimen is that they fully charge and then discharge the cells at 0.5c, meaning that they can only run 6 charge and discharge cycles in a 24 hour period. In other words, it would take 1000 days to run through the claimed 6000 cycles.
Have the "K"s even been manufactured and able to be tested for more than 1000 days?

It seems that we don't have much good information to go on here, but I find the idea that they all of a sudden made a mysterious change to the fundamental chemistry or construction of these cells that resulted in the lifecycles almost doubling to be pretty farfetched as well.

I'd like to hear what EVE or anyone with any actual knowledge of how this chemistry/tech works might say about this apparent huge leap in cell life expectancy.
And what magnitude of a difference would you expect to see by changing the testing regimen from 1c to 0.5c?

Everything you are saying is true in this post is true .... except a couple of people seem to be wanting to state emphatically that the difference of the charge rate in the spec is the only difference in these cells.
That is a ridiculous assumption ... especially since the dimensions are also different ..... that's all I'm trying to point out.
We have use EVE's spec sheets a lot on here to demonstrate certain characteristics of these cells .... I would think some sort of proof that their spec sheet isn't accurate when they claim 6000 cycles would be in order before making allegations.

 

[jtvt]

Maybe the question should be "Do N cells last 6000 cycles at 0.5c discharge?" I can answer this in 16 years.

The posts in K cells are farther apart and the cells are ~3mm taller.

Seems unlikely, but they could have had the K cells in development long enough to test them for a full 6000 cycles. However, I think probably they either tested the N cells at 0.5 and carried forward those specs to the K cells or they tested the K cells over a much shorter time frame and extrapolated the degredation results to 6000 cycles.

 

[jtvt]

BTW to follow up on divergence between the N and K cells and welded studs and no welded studs.

I see no difference. The cells behave the same. Welded studs don't make any difference. There is no extra resistance, etc causing problems.

 

[koobs]

BTW to follow up on divergence between the N and K cells and welded studs and no welded studs.

I see no difference. The cells behave the same. Welded studs don't make any difference. There is no extra resistance, etc causing problems.

Any issues with the smaller contact area on the welded studs, causing heating up at higher current loads?

 

[jtvt]

Any issues with the smaller contact area on the welded studs, causing heating up at higher current loads?

The most they have seen is ~50a and no issues with that.