Weird cell degradation

[pinkpanda3310]

I think not. Each cell is swolen at the positive end ie- top cell big on left side next cell big on right side.

if you puncture a lipo it will let air in....then it will start to react and oxidize.
if its punctured its as good as dead...and really smelly too
chris

[pinkpanda3310]

So you think they were poorly manufactured? That's why 4 of the cells have puffed in the same way. The pack is as good as dead but I was just curious about the deformation.

i did read up about lipos a few years ago, as a child i was into electronics....im more into mechanics and engineering rather than chemistry, so i didnt understand all of the text.

basically in certain situations like over discharge and over draw, oxygens are created inside the pack....puffing, the oxygene will start to oxydize the internal tabs on the lipo which pickup the voltage and take it out the pack.

this accelerates the degredation of the pack...once it starts there is no stopping it, basically rots the tabs...which creates more heat...

no i dont think they where poorly made...just well used
chris

[pinkpanda3310]

I can soughta understand that

Thanks for the insight Chris

one more fact i just thought of while i was just repairing a bouncy castle blower...DC voltage allways flows in one direction...this would explain why the packs are swollen at one end only..now i cant remember if its + to - or - to +.
durr.... the old grey matter is not as good as it used to be
chris

[BrianG]

Originally Posted by chrismechanic

one more fact i just thought of while i was just repairing a bouncy castle blower...DC voltage allways flows in one direction...this would explain why the packs are swollen at one end only..now i cant remember if its + to - or - to +.
durr.... the old grey matter is not as good as it used to be
chris

Most explanations of electric theory kinda assumes the flow goes from + to -, which is technically "hole flow". But electrons actually travel from - to +.

As to the OP; I still think it's more of a physical deformation than electrical. Maybe relative tightness of shrinkwrap in the center vs the ends? Maybe the straps slowly over time squeeze the middle more? Maybe an inner cell puffs under usage, and since they are all stacked up, the tightness of the heatshrink causes that bulge to squeeze the material of adjacent cells around? Since lipo cells are long/wide layers of material, any gas expansion would affect the entire surface area of the cell, and would tend to bulge in the middle.