Maximising Cell life

[leigh2025]

I am interested in maximising the cell life of the EVE and CATL cells as close to the maximum possible, this means i have to maintain compression at the beginning for the first few cycles, to make sure that no voids appear and we are setting the cells up for a long life. I am also aware that the cells will expand and contract over time (increasing as the SOC changes and cell cycles increase).

I have some assumptions that I would appreciate to be clarified or debunked

- We should have the 300 newtons of force on the cell for the first ~5 charge discharge cycles to help with cell forming and thus extends battery life.
- we only need the FR4 for electrical isolation, the EVA or poron can achieve isolation.
-there is a potential issue that EVA foam can deform and not 'spring' back, providing a potential void.
- having all the cell just clamped together with steel plate is bad because it doesn't adapt to the cells changing SOC and cycle life, meaning internal pressures can drastically increase over time.
- using calibrated springs is theoretically the best option but is over complex and you still need EVA/Fr4 for electrical isolation?

so the best option is official Poron, or EVA foam (not ebay). that can handle the consistant compression at least for the first 10 or so charge and discharge cyles (until the cell has formed in its best state). then the foam has done its job to a certain extent and can deform with the cell as it expands over time?

- is there official documentation from the cell manufacturers on how to assemble these packs , there must be up to date documentation on this to use their products properly? (i cant find it anywhere atm)

thanks!

 

[leigh2025]

Here are the two options i have so far, option 1 will either have a fixed tension (but i am worried about increase pressure over the cells life, or using the valve spring option (but add cost, complexity and size) ((and yes option 1 has FR4 isolation between cells).

option 2 has eva foam or poron foam, but the foam does not maintain its properties over time, but from what i have read so far, you only need the pressure for the first dozen or so cycles for cell forming...

 

[1234enough]

There are many posts on this, which I'm sure will answer any questions you have.
Personally I went compression springs, tested for projected movement and required kgf.

 

[justgary]

I am interested in maximising the cell life of the EVE and CATL cells as close to the maximum possible, this means i have to maintain compression at the beginning for the first few cycles, to make sure that no voids appear and we are setting the cells up for a long life. I am also aware that the cells will expand and contract over time (increasing as the SOC changes and cell cycles increase).

I have some assumptions that I would appreciate to be clarified or debunked

- We should have the 300 newtons of force on the cell for the first ~5 charge discharge cycles to help with cell forming and thus extends battery life.
- we only need the FR4 for electrical isolation, the EVA or poron can achieve isolation.
-there is a potential issue that EVA foam can deform and not 'spring' back, providing a potential void.
- having all the cell just clamped together with steel plate is bad because it doesn't adapt to the cells changing SOC and cycle life, meaning internal pressures can drastically increase over time.
- using calibrated springs is theoretically the best option but is over complex and you still need EVA/Fr4 for electrical isolation?

so the best option is official Poron, or EVA foam (not ebay). that can handle the consistant compression at least for the first 10 or so charge and discharge cyles (until the cell has formed in its best state). then the foam has done its job to a certain extent and can deform with the cell as it expands over time?

- is there official documentation from the cell manufacturers on how to assemble these packs , there must be up to date documentation on this to use their products properly? (i cant find it anywhere atm)

thanks!

You posted this exact same post Saturday. You didn't answer my questions then, so I won't repeat myself here.

 

[1234enough]

Maybe AI bot? Which doesn't like to answer

 

[leigh2025]

You posted this exact same post Saturday. You didn't answer my questions then, so I won't repeat myself here.

I brought this out of a thread into its own post. You mentioned that you've never heard of the compression for the first few cycles before. I have read that in the literature and there is conditioning of the cells for the first charge and discharge cycles. I have also put a picture on this post so it makes it clearer that the cells are not stacked together.

I though by now there would be design reference guides by the cell manufacturers on how to approach this. I am surprised that this is not a standardised approach by now. Does anyone have a reference design guide?

 

[leigh2025]

Maybe AI bot? Which doesn't like to answer

I'm not an AI bot, there wasn't a clear answer on my reply in an old thread, thats why i posted it on a new post.

 

[justgary]

I brought this out of a thread into its own post. You mentioned that you've never heard of the compression for the first few cycles before. I have read that in the literature and there is conditioning of the cells for the first charge and discharge cycles. I have also put a picture on this post so it makes it clearer that the cells are not stacked together.

I though by now there would be design reference guides by the cell manufacturers on how to approach this. I am surprised that this is not a standardised approach by now. Does anyone have a reference design guide?

Cell conditioning for the first few cycles has nothing to do with the fact that you need to provide proper compression for the lifetime of your cells.

You won't find a standard guide because you might be making (for example) a 4S, 8S, 15S, or 16S battery. Your battery might be for energy storage in a shed, or maybe you will use it in a vehicle like an RV or golf cart where it needs vibration resistance. Maybe it needs cooling. Maybe it needs heating.

The cell data sheet tells you what the cells need, but you are free to interpret those requirements and build them into your battery design.

Do you have evidence that Poron does not maintain its properties over time? Please provide it.