I've had some puffy ones that lived quite a while in the less demanding planes. I usually don't decommission them until a cell won't keep a charge. Even then I'll often take them apart and remove the bad cell, making a 4 cell into a 3 or a 3 into a 2. Again, messing with building your own cells from trashed parts isn't probably the best idea but if done with a little caution and common sense its not that bad.