Anyone buying these 305ah envision cells?
- Thread starter G00SE
- Start date
No. Just taped together using packing tape. I did not fully cycle them to limit cell bulging until I can properly compress them. Need to order some 1/2" alum plate for that.
This seems relevant to my concern:
Not sure what that means to start at 7% thicker though.
My 2 year old LF105 bulged about 0.6mm on average. Less than 10 partial cycles. They been mostly sitting at 13.6V as ballast battery for my 12V loads powered by DC-DC converter. When I bought them new they were perfectly flat with no light visible between cells. Corner cell in 2nd image looks warped due to lens distortion in my phone camera.
These are LF280 cells, from 2018, in use 24/7 since 2020 when I got them:
diysolarforum.com
No bloating, no bulging. Still flat as ever. Also note: no spacers/foam/compliant pad between them. Don't know if I will change that yet with the up and coming 30kWh upgrade.
LiFePO4 cells in use since 2020. Bloating? Capacity?
As some of you may know, I'm in the process of moving my batteries into a new enclosure. Reasons: it's more organized, space is better optimized, and I can add more batteries more easily later if needed. This is the first time I took these apart since I built them somewhere early 2020. I bought...
diysolarforum.com
No bloating, no bulging. Still flat as ever. Also note: no spacers/foam/compliant pad between them. Don't know if I will change that yet with the up and coming 30kWh upgrade.
That's because you had them clamped since they were new. But clamping them without compliant material risks damaging them long term as they age.
Yeah, I agree - but those threaded bars and wood should offer quite some flex. In any case, let's see if I change it with the upgrade.
ArthurEld
Solar Wizard
The cells bulge the most when they are fully charged.
I use a compression fixture.
And I set the compression when the cells are fully charged.
My cells haven't had anything between them either. That wasn't a thing a few years ago. Since my new cases come with the spacers, I will use them.
I use a compression fixture.
And I set the compression when the cells are fully charged.
My cells haven't had anything between them either. That wasn't a thing a few years ago. Since my new cases come with the spacers, I will use them.
blstringham
New Member
I ordered 32 of these and built 2*16s batteries. They are down to $75 each now and are usually out of stock within a few days. Both my batteries are working exceptionally. No problems with shipping. Packaging was top notch. The batteries are a bit swollen in the middle on the broad side but this can be expected and is fine. Lifepo4 will expand and contract no matter how perfectly you compress your batteries.
18650 will not replace it?
I have not asked, i dont want to have to take it out I already have it fully built into my XR-04 Enclosure, which I absolutely love BTW, for 250 shipped this thing is really well built, I have a 2nd one coming and will do pictures of it and the 2nd build, it's really nice and for the price unbeatable.
contact them. it seems to be a known issue. happened to me and they replaced it quickly with almost no questions asked
soakupthesun
New Member
So, I'm building my first LiFePO4 pack. 4S2P from new 105AH EVE cells, Overkillsolar BMS. Pretty standard stuff. Then I get to the whole compression topic...
I read the EVE data sheet, and I think we need to be a bit more pedantic about what it says, and more importantly what it doesn't say. The datasheet is only a spec for what comes out of the factory, and how to confirm / measure it (i.e. a QA document). The entire discussion in the datasheet regarding compression is under the section where they are specifying the battery cell dimensions. In other words, since the cells do swell with charging, in order to specify the product dimensions (the thing they are going after) they need to specify how much compression the cells are under. They spec'd 300 kgf for this test, describe the test jig, and under those conditions they show what the cell dimensions should be.
They did NOT specify that the cells should be operated at that compression (nor that they shouldn't be, to be clear). This is only a spec for the conditions to measure the dimensions of the cell.
An email exchange with the 18650 support team said that the cells should be used with compression, and pointed to the datasheet. That, in my pedantic mind, doesn't answer the question.
The only information I have seen about what compression should be applied is the graph that Brucey cited in post #441, but I don't believe that came from EVE.
Has anyone seen an actual "This is how you should mechanically construct a multi-cell battery with these cells." document from EVE?? (Or Envision for that matter, to stay on topic... I was going to use the 305's but they were out of stock.)
I read the EVE data sheet, and I think we need to be a bit more pedantic about what it says, and more importantly what it doesn't say. The datasheet is only a spec for what comes out of the factory, and how to confirm / measure it (i.e. a QA document). The entire discussion in the datasheet regarding compression is under the section where they are specifying the battery cell dimensions. In other words, since the cells do swell with charging, in order to specify the product dimensions (the thing they are going after) they need to specify how much compression the cells are under. They spec'd 300 kgf for this test, describe the test jig, and under those conditions they show what the cell dimensions should be.
They did NOT specify that the cells should be operated at that compression (nor that they shouldn't be, to be clear). This is only a spec for the conditions to measure the dimensions of the cell.
An email exchange with the 18650 support team said that the cells should be used with compression, and pointed to the datasheet. That, in my pedantic mind, doesn't answer the question.
The only information I have seen about what compression should be applied is the graph that Brucey cited in post #441, but I don't believe that came from EVE.
Has anyone seen an actual "This is how you should mechanically construct a multi-cell battery with these cells." document from EVE?? (Or Envision for that matter, to stay on topic... I was going to use the 305's but they were out of stock.)
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houseofancients
Solar Wizard
Wrong topic
Brucey
Solar Wizard
With the A123 graph, we can see that with zero compression lifecycle is 3000. With some pressure applied that shoots up to 6000 and then eventually nearly 20,000 cycles.
The majority of diyers prob won't reach that lower 3000 cycle limit due to having larger battery banks etc and calendar aging, so even if there is no compression applied the lifetime results will be good. But with newer cells like the lf560k rated for 12,000 cycles etc it would seem wise to use a fixture and apply pressure for prismatic cells.
Wouldn't these age out around the same time as a 304ah wasting even more cycles, or do they age differently?
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