Beginner DIY EVE 280AH Prismatic LiFePO4 cells system

Hi all,

Relatively new to the DIY battery route. Watched a load of Will's videos re Prismatic LiFePO4 cells and decided to go that route.
Basically from my preview building as opposed to buying drop in LiFePO4 replacement is a no brainer when cost comparisons are made.

My first question is;
When building the each battery do the EVE Prismatic cells require mounting solidly back to back to avoid thermal 'distortion' or 'bulging' ?

Eoin said:

When building the each battery do the EVE Prismatic cells require mounting solidly back to back to avoid thermal 'distortion' or 'bulging' ?

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Yes. Compression keeps the anode, cathode, and electrolyte from migrating during charge/discharge cycles. Read the threads here on cell compression.

The EVE datasheet specifies a compression force of 300kgf (660 pounds), or basically 12 PSI over the broad face of the cells. Use an insulating sheet such as FR4 PC board material between each cell, and also insulate at the bottom and sides to make sure that the cell cases can never touch or have something rub through the thin blue skin.

justgary said:

Yes. Compression keeps the anode, cathode, and electrolyte from migrating during charge/discharge cycles. Read the threads here on cell compression.

The EVE datasheet specifies a compression force of 300kgf (660 pounds), or basically 12 PSI over the broad face of the cells. Use an insulating sheet such as FR4 PC board material between each cell, and also insulate at the bottom and sides to make sure that the cell cases can never touch or have something rub through the thin blue skin.

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Many thanks for the concise answer Gary

Just recieved my EVE cells today... so let the fun begin ?

A question here guys these are supposed to be EVE Grade A 280AH cells.

I have slight concave deformation on all faces, doesn't appear to be the thermal bloating and or bulging that I've seen on videos when people get supplied Grade B. Nonetheless, while very slight its noticable when a straight edge is placed against the face.

Is this normal deformity when these flimsy walled cells are charged by the factory without compression before shipping to us?

Also surprising enough none of the QR codes work with the phone camera ?

Concave could mean they are just at a low charge. The opposite of bulging outward right? Where did you purchase your cells?

There's a lot of fuss about getting perfect compression on your batteries but at the end of the day while you might extend their life a bit you're unlikely to reach the full duty cycle lifetime of the batteries without compression anyway. I went for firmly wrapped with HDPE sheets between the cells and kept firmly in place with foam. I don't think there's a need for the compression with threaded rods etc that you see a lot of. Personal opinion and depends on use case.

Are you using the lifepo4 cell app to check the qr codes?

Thanks for the reply ShaneC and I bought them from this supplier and this is their exact link to my batch...

Eve LF280K v3 Prismatic 280Ah - LiFePO4 - 3.2V A-grade - Prismatic - LiFePO4 - Rechargeable batteries | NKON

Capacity report available. Height of the studs: 13mm

eu.nkon.nl

Also my research has me led to conflicting results on actual real time data re extended life cycles if one adhered to specified compression or not! I know we must/should adhere to manufacturer's specifications and requirements.
And so yup I will add compression since it appears to be stated on EVE's actual website.

And finally I hadn't realised there was an actual 'LiFePO4 Cell App' . So no to answer your question I didn't use it. I'll do a Google and find it and try it.

Thanks for the advice

The reasons for choosing that supplier were;

1. Watching Will's videos he appears to praise EVE grade A cells for their pricing and capabilities.

2. I'm in Ireland and was looking for a European supplier, obviously basing my selection on EU directives of imports and online purchasing protection for buyers.

3. Didn't want and or trust to buy directly from China with the costs involved. It may not be much for some but for me it's a huge investment.

4. Also looking for a supplier that supports PayPal. (I use PayPal for all my online purchasing, and the once I had to contact them they refunded me in full within a few days and took on the fraudulent supplier themselves)

5. And finally the reviews were pretty good about the supplier. I had a couple of emails pre purchase and prompt replies.

Eoin said:

Thanks for the reply ShaneC and I bought them from this supplier and this is their exact link to my batch...

Eve LF280K v3 Prismatic 280Ah - LiFePO4 - 3.2V A-grade - Prismatic - LiFePO4 - Rechargeable batteries | NKON

Capacity report available. Height of the studs: 13mm

eu.nkon.nl

Also my research has me led to conflicting results on actual real time data re extended life cycles if one adhered to specified compression or not! I know we must/should adhere to manufacturer's specifications and requirements.
And so yup I will add compression since it appears to be stated on EVE's actual website.

And finally I hadn't realised there was an actual 'LiFePO4 Cell App' . So no to answer your question I didn't use it. I'll do a Google and find it and try it.

Thanks for the advice

Click to expand...

I used 2 x Mason DIY 280 Kits from Alibaba to compress and install my 16x2 eve 280h cells. The installation was a breeze and they have been working well for the past 4 months.

Eoin said:

Also surprising enough none of the QR codes work with the phone camera

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Please post an example photo of your codes.

Your link to the vendor states that capacity reports are available. Did you get them for your cells?

justgary said:

Please post an example photo of your codes.

Your link to the vendor states that capacity reports are available. Did you get them for your cells?

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I've sent an email yesterday thanking him for his speedy delivery and asked for the certification to be forwarded by return email.

But I guess he's busier these days in replying since I've received my order than he was when I was a perspective buyer ?

Just to add to my previous post I had requested certification within my order.

I'm not too worried (yet) as the cells certainly don't appear bloated.

And in fairness to the supplier I recieved my cells extremely quickly so much so that I'm waiting for my capacity tester and inverter/charger to be delivered.

ShaneC said:

Are you using the lifepo4 cell app to check the qr codes?

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I downloaded the app many thanks?
and sure enough apart from one cell that just won't scan... all the other cell's respective data is visible within the app.

It sounds like the seller is legit and the cells should be fine then. I'm in the UK (from Ireland ? ) and bought mine off fogstar.co.uk, they might deliver to Ireland if you need a different supplier in the future for whatever reason.

EVE are good cells, I also have their 280ah ones for a 24V battery build. w.r.t compression they state that you can compress and provide the values for that. I don't believe that you *have* to compress. You will prolong battery life somewhat if you do, I chose not to as it will take me a very long time to reach even 3000 full cycles, my charging/discharging is less than 1C a day. The Off Grid Garage guy did a good video on it:

Obviously that's only one voice among many but it was enough to convince me that I'll be fine. As I said in my last reply my cells have some compression just because of the wrapping tape and foam to keep them very solidly emplaced within the box.

You can have a look at my battery here:

ShaneC said:

It sounds like the seller is legit and the cells should be fine then. I'm in the UK (from Ireland ? ) and bought mine off fogstar.co.uk, they might deliver to Ireland if you need a different supplier in the future for whatever reason.

EVE are good cells, I also have their 280ah ones for a 24V battery build. w.r.t compression they state that you can compress and provide the values for that. I don't believe that you *have* to compress. You will prolong battery life somewhat if you do, I chose not to as it will take me a very long time to reach even 3000 full cycles, my charging/discharging is less than 1C a day. The Off Grid Garage guy did a good video on it:

Obviously that's only one voice among many but it was enough to convince me that I'll be fine. As I said in my last reply my cells have some compression just because of the wrapping tape and foam to keep them very solidly emplaced within the box.

You can have a look at my battery here:

Rate my battery: 280ah 24V

Hi all, Just wanted to show off my battery as I'm quite proud of how neat it's turned out while also double checking that I haven't messed anything up as its my first go. It consists of 8x 280ah Eve B-grade cells, about £950. Bought from fogstar.co.uk they came capacity tested, batched and...

diysolarforum.com

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Pretty cool setup just had a look, and regarding your UK cell supplier Brexit pretty much hammered us from buying from the UK unfortunately.
I used to buy from a UK Marine supplier but the import duties were brutal after Brexit and even we get double charges when ordering from Amazon.co.uk since also.

I'll have to build a slightly more robust battery box as I'll be placing my bank in my boat. Have a few iterations rolling around and haven't decided on the final version yet. But will be based on GRP and epoxy. If I find a supplier who mass produces them cheaper than I can mould them I may go that route, as there's no need to reinvent the wheel ? .

Also I had initially decided on a 24v set up with a two 8 cell configuration and bought the overkill 24v BMS but a mate kinda talked me out of it. So I've 4 120A overkill BMS's on order and should be here within a week.

I have the solar side built already and outputing power to two 110 AH @ lead acid batteries already.
These I'll be swapping out and will have to reset my MPPT and BM and then set them for LiFePO4.

Are you going 48v then, 4 batteries in series? That's probably a good idea, I think there's more choices for systems at that voltage, lots of nice looking AIOs if that takes your fancy. Plus cheaper cables are always a bonus, that's one of the reasons why I went 24v.

And yea I haven't had to order anything to home yet so haven't experienced the import duties.

ShaneC said:

Are you going 48v then, 4 batteries in parallel? That's probably a good idea, I think there's more choices for systems at that voltage, lots of nice looking AIOs if that takes your fancy. Plus cheaper cables are always a bonus, that's one of the reasons why I went 24v.

And yea I haven't had to order anything to home yet so haven't experienced the import duties.

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Nope staying 12V for Marine use for this build

ShaneC said:

The Off Grid Garage guy did a good video on it:

Click to expand...

I see his argument as saying, "Why quit smoking, drinking, and eating poorly since you are just going to die anyway?"

His whole argument is premised on a few (possibly incorrect) cycle life plots and a presumed calendar life. Calendar life may well be altered by correct compression since the anode, cathode, and electrolyte can't move around as easily. It is cheap and easy to do what the manufacturers recommend, so why ignore it and let your cells smoke, drink, and eat poorly?

justgary said:

It is cheap and easy to do what the manufacturers recommend, so why ignore it and let your cells smoke, drink, and eat poorly?

Click to expand...

Yeah as I said previously I'll be using compression, if it's in the specs well then the manufacturer has a reason for it. Also these Prismatic LiFePO4 cells casings are quite flimsy. And seeing some of Will's videos they do get quite irreversibly distorted.

Recieved a ream of certs, specs and capacity tests from the supplier so will have a wee bit of reading for the weekend (something I hate doing ?) me I'm a pragmatist and practical guy. Prefer to be doing and building not reading?.

Also received my capacity tester too and I ordered the one again recommend by Will in his capacity testing video.

Fantastic service it only took "three days" to get from DFW Airport, TX USA to me in Ireland

So a little update...
Inverter Charger finally arrived and so did the Overkill Solar BMS.
Wired the cells in 4s × 4of connected BMS and charged them to 3.60V.
Then disconnected them and wired the the 16 cells in parallel for the Top Balancing.
Connected the parallel string to my CV PS with a setting of 3.65A and current up full to its max of only 6A.
And so at last I finally have all my cells charged and Top Balanced and ready for their first capacity testing?.

And for any new prospective DIY enthusiast who's reading this and also also maybe contemplating following my route. With a CV (Constant Voltage) PS (Power Supply Unit) when you set the output Voltage to your specific settings. In my case 3.65V as that's the EVE LiFePO4 cells recommended max Voltage. And when you connect the PS to your cells...
As the voltage rises within the cells to the 3.65V setting, the current or amperage (A) output from the PS slowly drops to zero.

And just to clarify my last post when I said "..charged them to 3.60V..."
what I should have typed was "
...I set the BMS to 3.60V or 14.4V for each 12v Battery..."
Because I wanted to complete the last and final charge to 3.65V with my PS unit during the Top Balancing phase.

Another update!
Top Balancing completed (extremely long process for a bank of this capacity despite most cells were at 3.60v) then using my 6a PS it totalled a tad over 6 hrs to bring all cells equally to full capacity!

But the first capacity test wasn't too impressive slightly disappointing ?.

However the cells were discharging equally within each battery and depending on which BMS I selected for monitoring the cell imbalance were 0.005v , 0.010v , 0.011v and 0.004v.

One thing I noted was as the bank discharged from 2% to 0% (edit: 2% to 0%=cell capacity) the cell imbalances climbed and alternated between 0.004v and 0.102v.
(However, as the bank is currently recharging a good thing to note is all cells have returned to their original minimal cell imbalance readings as listed above)

My setup is temporary during testing phases on my table top, all leads are approximately same length, and only 3ft lengths at 35mm² x 2 (75mm² total) connecting the inverter/charger to the battery bank bus bars, and using custom made bus bars to connect the battery bank in parallel to complete the bank. The bus bar is 25mm X 3mm (75mm²) copper.

My set up of four 280ah batteries @ gives a total of battery bank capacity of 1,120ah.

My initial test results maxed out at 1,089ah ?.

I'm going to repeat the test after the loooonng recharge to full capacity of my bank.
I'm using my Victron BMV 712 BM and shunt for this capacity test. It's relatively new and only in use for the past two months on board.
And I disconnected and removed it from my boat for the testing phases as this is an extremely accurate piece of equipment.
And while I inputted the correct settings for my LiFePO4 cells (as opposed to the lead acid that's its measuring presently) I then made the rookie mistake of forgetting to actually "reset history", so I'm going to hold my hand up and suggested that maybe the lack of resetting has somehow given me an inaccurate reading??

I'm open to opinions here though ?

On a slightly different note I couldn't get my android phone to connect to my Overkill BMS kept getting a popup of "Enter Password" and got no further it simply froze.

So uninstalled it and despite following the setup on Overkill website and BMS manual all three links by Overkill on their website, their pdf manual and also an email link that I recieved from Overkill support none of them worked???

Ironically the link in Will's website was the only android Overkill BMS app that worked but it's still not the same screen as he shows on his YouTube review.
But honestly i didn't mind the appearance of the app as it now works and there's an impressive array of data that can be fine tuned and I can connect and disconnect at ease and repeatedly without issues ?

Capacity testing over and satisfactory results.

I set the low disconnect to 2.6v and max disconnect to 3.6v and still pulled the 1,120ah, which I'm happy with as I could have drawn more AH by maxing out the low and high disconnect settings.
Also with individual 4s batteries averaging 10.8v when the test was over and despite some deformation in the Cells as delivered, as I mentioned earlier in the thread I'm happy with the test end results.

My tests were carried out at an average cell temperature of 21°C to 25.5°C and a rate of 0.125C discharge.

While theoretically I could have carried out a 0.2C test as the EVE specs state for test results.

I had to reduce my test loads because rather than stressing a new and 'costly' inverter, as I was getting periodically 'overload' warnings from my inverter at the 0.2C load. I stopped the test, recharged the bank and used a domestic heater pulling an average of 1,697w hence the 0.125C load testing.

Also I repeated logging the voltage recordings at every 10% of battery bank discharge. And again the cell imbalance was minimal until almost cell depletion. However when recharged each time cell imbalance returned to stable minimal imbalance readings.

Few Questions here guys;
With a minimum cell imbalance during normal charge and discharge, does this suggest healthy cell internal resistance?

Also out of curiosity would ye insist on a 0.2C testing for new cells? And why?

Finished making the cell compression frames this evening, using 304L Stainless Steel 6mm (¼") flat bar welded into a frame structure.

Also I'm placing 6mm polycarbonate sheets inbetween each cell as insulation just incase for some reason there's a rip or tear in the flimsy aluminium EVE cells coating, and marine ply at the ends.

While others have used similar insulation sheeting like FR4 and HDPE it was easier to source polycarbonate from a local supplier.
And the melting point of polycarbonate isn't too far off that of FR4 .
Also I realised his evening I'll have to make new bus bars also, as those supplied for joining the cells are too short as the 6mm polycarbonate has increased the distance between the cell terminals.

So tomorrow I'll disassemble my bank and fit everything and share the pics.

These projects can be time consuming? but the experience gained from these builds is immeasurable.