Originally Posted by HarryC

It's possible that you are not charging them correctly. Despite being lithium ions you do not use the Li-ion setting on your charger. The Li-ion peak voltage used by a charger is less than the peak voltage of Jeti Power Ions, so they will be under-charged and therefore give less than the claimed capacity. The peak voltage of Power Ions is 4.2V per cell and you should charge them using the Lipo setting on your charger.