Lithium Iron Phosphate
(LiFePO4) and Lithium Manganese Oxide
(LiMn2O4) are two
different types of Li-Ion batteries and both of these are therefore charged in a similar fashion using a Li-Ion battery charger.
The chargers will both charge at constant fixed current until the maximum voltage is reached and then automatically continue charging at the fixed maximum voltage until the current falls below a predetermined level
(this is often referred to as constant current/constant voltage charging).
The main difference in the two 48V chargers is the maximum output voltage, which is usually clearly marked on the charger:
The output voltage of the LiFePO
4 chargers should be 58.4V
(16 cells @ 3.65V) whereas the older LiMn
2O
4 chargers were only 54.6V
(13 cells @ 4.2V).
I suspect the reason they are labelled
"for Li Ion battery only" is to try and ensure that they are not used with incompatible battery types such as NiCd or NiMh etc. as this could easily damage the battery and in some cases it can even make batteries explode.
Alan