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EVE-280 cells should these be clamped tight or spaced for expansion?

Am I missing something or are these cells only being held down by 4 tywraps? If so a standard car battery hold down is substantially more secure.

Don't want to be a downer, but this does not appear to be safe for travel in any way.
You are correct, there are four cable ties per battery, but in my defense...they are heavy...and would have to clear the 2" base before they could go any where...I am comfortable that unless I tip over, those batteries are going to be in the same place when I arrive. :)
 
Hello guys.

I was in the same situation a month ago, and after my first top balance discovered that the cells can swell up a lot, for example, this cells use to sit perfectly flat, and this happened after a low C rate charge, a couple of mm of separation:

1592262094653.png

Its not that bad and its between spec, but aside from the recommendation from EVE of adding pressure, the nordkyn desing web also recommends a fixture to prevent "delamination" from the expansion / contraption cycles.

Cells are probably going to be OK with, or without it..., but i invested a lot of $$ on my system and want to make it last as long as possible. So if i can spend a couple of days and some dollars to make a fixture and just maybe get 500 - 1000 more cycles, ill do it.

This is some solutions from marinehowto and nordkyn desing:

LFP-200Ah-with-BMS-768x1024.jpg1590948580061.png


Very easy to make, only problem would be the heat disipation that migh drecrease the lifespan a little bit (Probably neglilible with our lower C rates)

I decided to make a full enclosure:

1592262358800.png
1592262370362.png
1592262411722.png

  • Have aluminum flatbars and "T" extrusions to allow some airflow betwen cells, so heat wont be much of a problem.
  • Can mount both horizontallly and vertically, also could fix to the wall.
  • Can "easily" transport the full pack to connect between systems. (Probably not needed for a lot of people, but usefull for me).
  • Can easily change the BMS, as the leads are connected to a connection bar.
  • Looks better!
And as you can see, i have 4 x threaded rods in the design, so i can put the 300KGF if i want, in practice i just compress them a bit as i dont know how to calculate or measure that... i guess you can calculate that with a torquimeter or just measure with a pressure plate.

The cell walls stay completely flat with the middle flatbars and resistant aluminum structure in both sides.

So far im happy with the build!
 
I thought the LiFePO4 batteries could be used in any orientation. Urban legend?

BattleBorn says mount them how you want:

Yes, you can mount your battery in any position. There is no acid inside of the battery, and the small amount of liquid electrolyte is contained within each sealed cell.

You can decide what is best for your application. Our lithium technology gives you the flexibility to put the battery in places you normally would not have placed a lead acid battery.

Upside down would be kind of stupid, of course.
 
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I thought the LiFePO4 batteries could be used in any orientation. Urban legend?

BattleBorn says mount them how you want:



Upside down would be kind of stupid, of course.
battleborn uses cylindrical cells.
I've seen anecdotes that suggest it might be best for prismatic cells to be clamped in a terminals up orientation.
 
I found this:

"it's to do with electrolyte level - however, it's not really to do with the safety valve. There is only a small amount of electrolyte in each cell. The plates "wick" the electrolyte so they need to have their "feet in the water" so to speak. Imagine the plates having a sponge cover (I am not a battery engineer and I don't know the exact construction details!). When they sit in electrolyte they can soak up more. If they don't have contact with the electrolyte pool they will dry out and become ineffective. So when the cell is flat the top plates can suffer from electrolyte starvation.
When standing upright or when on the narrow edge the blow-out valve can function without venting electrolyte. Note the blow-out valve still works with the cell on it's side but it will vent some of the electrolyte while doing so. However, by the time the blow-out valve pops your cell is too far gone to recover (regardless of whether the electrolyte remains in the cell or not). This valve is a last stand safety measure - not a means of normal operation. Even lying flat the valve has achieved it's main purpose - preventing a dangerous build up of pressure. It just did it more messily than when the cell is in the other two orientations."


And more interestingly, I found this:

"It is demonstrated that the phase transition paths are not strictly single- or two-phase insertion processes but are highly orientation-dependent even at a low charge/discharge rate.This work presents thefirst direct experimental evidence that decreasing the dimension in the [100] direction can remarkably improve the solid solubility of both the end solid solutions(LiαFePO4and Li1−βFePO4) and decrease the lithium miscibility gap of LFP. The identification of an orientation-dependent miscibility gap enriches the understanding of the transition mechanism in LFP and highlights the importance of orientation-controlled crystal synthesis to enable high-rate charge and discharge, rather than focusing solely on decreasing the size in the [010] direction along which lithium undergoes a curved one-dimensional chain motion31by cooperative filling of the (bc)Pnmaplane.32"

My layman interpretation: orientation does matter as affects how the crystals grow which affects charge/discharge rate and capacity.
 
This retailer says terminals up: https://shop.gwl.eu/index.php?cl=knowledgebase&KBId=1523
This prismatic battery maker (retailer?) says any orientation: https://hardkorrlighting.com/en-nz/product/100ah-lithium-lifepo4-deep-cycle-battery/

I'm thinking that terminals up is the safe recommendation, unless the battery manufacturer explicitly (in writing) says that other orientations are OK. I'm used to the Odyssey AGM batteries that can be mounted in any orientation. I was planning to put mine in sideways. I'll have to rethink that.
 
Well there is a lot of contradictory information about the cell orientation, so im still unsure about the answer.

- A lot of resources point to the "Any orientation" advice, however a lot of them refer to cilindrical cells, or batteries asembled with them (Like battleborns), so that doesnt apply to our prismatics.
- There is some resources that say prismatics are ok on the side, and they say that older generations couldnt be placed on this configuration, but with newer cells its OK.
- The most repeated issue its the electrolite and venting problem if they fail... howemever as you mention if the cells are ventin they are too far long, so it doesnt matter.
- What i didnt find, its the electrolite absortion that @sremick mentions, pretty interesting, and after reading that im considering turning my bank to the side.

But as i mention, still not a definitive answer, most likely ill keep searching and put them upright at the moment.
 
- A lot of resources point to the "Any orientation" advice, however a lot of them refer to cilindrical cells, or batteries asembled with them (Like battleborns), so that doesnt apply to our prismatics.
Yeah, if the primary issue is electrolyte "wicking" then it makes total sense that cylindrical cells don't care, but prismatic would.

I'm no expert, but if I'm dealing with expensive high-energy-density power storage devices, I'm likely to lean towards playing it safe whenever possible.
 
With regard to the busbars, if the cells are secured well enough, I don't think the busbars are going to be affected by the movement of the vehicle. I intend to use the busbars provided by the vendor.
 
I decided to make a full enclosure:

View attachment 15537
View attachment 15538


  • Have aluminum flatbars and "T" extrusions to allow some airflow betwen cells, so heat wont be much of a problem.
  • Can mount both horizontallly and vertically, also could fix to the wall.
  • Can "easily" transport the full pack to connect between systems. (Probably not needed for a lot of people, but usefull for me).
  • Can easily change the BMS, as the leads are connected to a connection bar.
  • Looks better!
And as you can see, i have 4 x threaded rods in the design, so i can put the 300KGF if i want, in practice i just compress them a bit as i dont know how to calculate or measure that... i guess you can calculate that with a torquimeter or just measure with a pressure plate.

The cell walls stay completely flat with the middle flatbars and resistant aluminum structure in both sides.

So far im happy with the build!

Don't know how difficult it was for you to build those but have you considered selling a kit for someone to build that same battery enclosure?
 
Yeah, if the primary issue is electrolyte "wicking" then it makes total sense that cylindrical cells don't care, but prismatic would.

I'm no expert, but if I'm dealing with expensive high-energy-density power storage devices, I'm likely to lean towards playing it safe whenever possible.

Good plan, some time ago i decided that vertical mounting was safe enough but unfortunately i didnt save the info that conviced me of that... ill do some more research to see if i change my mind; howemever my final setup was considering horizontal configuration aniways, and i put them vertical for some time to have more space to work around the inverters.... but i will also play it safe and put them in the proper position.... and i will be back if i found more clear data about the positioning!

Don't know how difficult it was for you to build those but have you considered selling a kit for someone to build that same battery enclosure?

Its an easy assembly, a little time consuming since i was making the design while building it... but after this first two i can do more a lot faster.

Its a good idea, and i mention before that i plan on posting the drawings in case they are useful for someone else... but haven't had the time and also im still improving the build.

Maybe at some point in the future i could!, but right now too busy for that... but ill find the time to post the drawings and the full process to the forum :)
 
Which "side" is the side they mean you shouldn't put them on? The narrow side?
I am making the assumption he is saying do not stack them on the narrow side. My logic is they will have more surface area and internally that is the same plane that the pouches are aligned.
Besides I already have a plan and that fits my plan. ;)
 
@mrdavvv and all

FYI - Reached out to EVE directly since I have a 66 of the LF280 cells on order to confirm orientation when building a battery bank - upright, flat or on the side. Received the following response:

View attachment 16127


Great!.

Now i just remembered why i considered "vertical" mounting good enough!, some people in another forum asked some manufacturers and they also recommended either upright or lying on the bigger side. (Unfortunately couldn't find the thread).

Funnily enough a lot of people on the internet recommends to install them on the short side, but never on the bigger side.... contrary to what Eve is saying, guess it depends on the cells.

@Ampster Whats your plan?, also on the big side?
 
@Ampster Whats your plan?, also on the big side?
Yes on the big side in 4 columns of 8 cells high. They fit nicely in a 30 x 30 metal wall cabinet. They will be clamped. Even though I will have a BMS, I like having access to the terminals for ease of manual testing.
 
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