what are your thoughts about cell compression? i see you have T shaped extruded aluminium between the cells. but i also read something in the spec sheat about cell compression. so what would you suggest when there is an light load applied. so no heat issues at all.
it does look pretty darn nice tho. and easy to lift/handle
Hello!, about the cell compresion, we were talking about it in this thread:
https://diysolarforum.com/threads/do-my-new-blue-cells-need-to-be-packed-together.3836/page-3
Basically the Eve cells datasheet shows a significant difference between uncompresed / compresed lifespans. Howemever its up to discussion if this apply to our lower C rate application, where the heat and expansion arent probably a concern, Solar its not very demanding compared with EVs and other applications.
So some people in the forum recomend to not worry about it and just strap them, wich i think its ok... howemever after my first chargin cycles i noticed that they swell up... a lot more than i expected (Wich its probably between manufacturer tolerances)... howemever i didnt like that (you can check my post in the linked thread about this).... and after reading something about the pressure preventing electrode delamination from Nordkyng design, i decided to do something about it.
Only problem about clamping them, its that they will run hotter, and heat its a killer for this batteries. Probably not a problem if you dont charge / discharge at higher rates... but its a compromise, do you want to extend the lifespan by compressing, or by reducing heat?. For example, check some dissasembly videos of the BYD packs, they are strapped / clamped but they have huge aluminum heatsinks and forced ventilation... howemever they were used by EVs or battery farms i think!.
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So my design requirements where:
- Portable
- Able to clamp the cells
- Able to have some airflow
Also i liked a lot the ability to move the full pack in a matter of minutes without disconnecting all the cells!... im placing hydrid inverters in both my office / home with LIFEPO4 battery backup, and i plan to have if possible 3 or maybe 4 - 560Ah banks at some point.... with this design i can move them between places if necessary in case of extended failure on the main grid or increase capacity depending of my requirements. They are very heavy so its better to move them with some help!... around 45 kg each bank!
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The cells are divided by the 2 x T aluminum profile, and also same thickness flatbars in the middle so they press each other, avoiding swelling from the middle of the cell. There is some air space between the cells thanks to this configuration, so i have both pressure and some air flow in my cells, in theory they should last longer with this racks!.. I spend some serious $$ of my 16 cells, so everything i can do to extend their lifespan its a good investment i think, the aluminum its cheap and it took me about 2 days to finish them so im happy with it!... and still not finished!.. i plan on adding some plastic coverings and battery posts so it looks nicer!
, just rusty english (no native). Pretty interesting still, maybe i have been writing it wrong all this years you are the only one that ever stopped to mention it!... should start using the spellchecker a little more 