3.2. check after two weeks for weak (ie, high self discharge) cells.
Like all other lithium ion chemistry's, LiFe likes to be stored at as low as possible SoC.
Low as possible means.. balancing the following parameters: 1. time of storage vs 2. self discharge of the cells vs 3. cell wear from a single deep cycle.
great quality modern cells like Panasonic cells (especially extreme high volume cells like Tesla Model S cells) have very low self discharge which means you can discharge them to 5% SoC (3.2V per cell or so) and leave them there for years.
But lower volume cells need a little more monitoring. A123's pouch cells are great in my experience, however. I've kept them stored for a year and they hold like a rock with no measurable voltage loss. Maybe their cylindrical cells are the same way.
A123, panasonic, sanyo, samsung, lg, sony, all of these I would feel good about discharging to 5% for long term storage.
Lower quality manufactures like all chinese.. headway, ping, thundersuck, etc etc etc... totally different story.
