I agree with the comporession method.
All the packs i built have compression on them,, LiPo, LiMn and LiFePo4. All are still 100% working today, none have puffed yet :wink: and RI always stay low. so i can charge them at nominal rate or more without problem :wink:
For the lipo i also think it help reduce the danger.
Like i explained many times on E-S in the past, problem with pouch is that once they inflate (puff), the corner and edges on the side will have deformation and this is what might cause them to catch fire if they puff too hard. When deformation occur the conductive anode and cathode layers inside might short together as well as when a cell have puncture theu the layers.
Compressing pouches cells keep them in original shape and also keep layers closer wich help for the RI to stay low :wink:
Most of the lipo fire occur with pack assembled together with ducktape or simple shrink and sometime just inside a nylon bag where they can move and hit edges of the bicycle frame wich is very bad.
Building a case to protect them and hold the pouch together and keep them under pressure on the tickness axis is the key and it worked for me for many years.
The guy o fthe RIMAC car wich i consider as one of the genious in the high performance EV developpment also use that method and most o fthe EV manufacture are also using that method.
now..
As for the cylindrical cells, they dont need compression because they already are under compression!.. cylindrical shape is one of the shape that is the most strong to sustain pressure.
Layers expansion occur when cells are charged for the lipo and they also have an endothermic reaction wich make them to cool down!. once they are discharged they shrink a little bit.
TRICK:
One of the trick i have for pouch cells is to make the battery box with dimension of the cells in their discharged state ( when their tickness is at his thinner state) then when they are installed in their battery box, if they try to inflate furing the charging process, this will make them to autocompress and will keep the RI low and keep them in original shape. then when they discharge, they recover their uncompressed original shape :wink: This cycle repeat over the lifetime of the cells :wink:
It is so constant than i just have to knock on the cell box and the sound pitch give me an idea of teh state of charge :wink:
What are you waiting for guys! :wink:
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