Last year all 3 of my Orion 5400's puffed slightly and I just ran them all year and sold them cheap at the end of the season lol. I had a IP 5000 lipo that was severely puffed and it scared me so it sat in storage until I dropped it off at my battery recycling center at the local dump.
Not just saying this because this is an AE forum, but this year i'm running only Reedy lipos and neither one of my 4S or 2S lipos have puffed even slightly I don't know if it's just lipo technology improving or if Reedy is just using quality cells? I never run my lipos below 3V/cell and have never overheated them.
I read somewhere, wish I could find it so it could be added to this forum, that it's normal for a lipo to puff up to 15% during a "load cycle" and be OK. What I don't remember is IF the puff should go away or stay within the 15%.
If a lipo puffs to the point that seems bad, I have a one auto lamp discharger. The "older" racers should remember the multi-lamp nicad Deans discharger, it's like that but with only one lamp.
Yeah I think some slight puffing with some brands is normal. Problem is I don't think there's any affirmitive answer as to the safety and performance of a puffed pack. Lipo technology in RC is still relatively new and the chemistry of lipos are rapidly evolving which really means no long term testing of any particular lipos on the market.
I charged my puffed pack tonight. Cell #2 was totally dead. My charger refuse to charge the pack. After a little fight with the charger and the pack, the charger finally accepted to charge my dead pack.
Cell #2 was at 2v while the three others cells were between 2.8v and 3.2v.
To make a long story short, I've charged the pack until all cells reached the 4.0v mark. I run the pack in my buggy for 4-5 minutes. My charger shows all my cells now between 3.8v and 3.85v. Not too bad. I gonna fully charge my pack tomorrow and run it again.
If any of your lipo cells have dropped below 2.8 volts at any point I would I would recommend against using them. Even if you manage to recover the cells to where they seem good from a voltage standpoint the internal resistance has likely risen to the point where the battery current output will self limit (which means less punch and more heat being built up in the cell that was below 2.8 volts). Eventually this will lead to overheating then catastrophic failure (though if you are lucky the pack will become too poor a performer to be worthwhile before you set fire to anything expensive or irreplaceable).
I have a slightly puffed trakpower 4s 5600 60c and it still takes a charge, stays balanced and performance hasn't changed. I was nervous at first, but not too much now.
I have set my esc to shut off at 3.25v per cell now.
My Blue lipo 4s/30c 5000mah puffed up after a run but not really bad its still like that but charges and runs fine . The Puffed pack thing is kinda of overated i know a guy i race with that had his puff up kind of good all he does is let them cool compeltly down and throw it back on the charger and seems fine .
Just make sure you dont overgear or have something binding that will make the lipo hot and puff up worse.
I dont really remmend that though if its that bad lol.