I'm with Kirk on this one; Long time storage of Lithium batteries should be at their rated voltage (3.6/3.7V for LiCo and LiMn, and 3.3V for LiFePo).
Dennis;
If your 48V GM pack has 16 cells and the charger are 58V, then each cell gets max 3.625V at End-of-charge, which is a nice compromise between capacity and longlivety for LiFePo4 cells.
LiFePo should have a max charge of 3.650V, and those 0.025V you're missing, results in maybe 1-2% capacity, but you gain a more assured life for your cells.
Charging LiFePo's at 3.70V + are a guaranteed cell-life-killer; charging at 4.0V++ are to play with your life and your enviroment, and will most certainly destroy your cells..
(All Rechargeable Lithium cells today have a thermal vent that pops when overheating, to prevent an explosion. Cobalt-based cells (like in your laptop and mobile phone) does this at around 150deg. C., and LiMn etc. and LiFePo, around 250Deg. C.) They also have an over-discharge-fuse that snaps if shorted etc.
Both of thos things above renders the cell useless afterwards.
No need to discharge newly charged cells; just do not charge them to the absolute max charging voltage. That way, they'll keep their long life.
Regarding self-discharge; I think Lithium have a 5% loss the first day, then 1-2% self-discharge/week.
Most Lithium cells today handles cold temperatures well, except that they'll have lower capacity, that is. But they should Never be charged below freezing!