Lithium batteries are both a great alternative for energy storage however they have their problems. Until a new generation of battery is distributed on the market, we have to contend with the following difficulties with the lithium type. Here is a list:

• Batteries are chemical based - which means they will degrade over time from both, oxidation and from from use. Even when a chemically based battery is not in use, it is being depleted.
• Charge rate: The higher the charge rate (in amps) the quicker the battery will be ready for use - the disadvantage of a "quick charge" is the membrane of which the active material is moved to (during the charging process) holds these materials and locks them into this membrane. This happens even if you take great care of the battery, however when you subject the battery to a high or fast charge, more of the material (partly lithium) gets trapped into this membrane and will not return back to the uncharged state. So fast charging has a penalty - shorter battery life. You trade convenience for battery life.
• Heat - is the enemy of lithium batteries. A fast charge (along with exposure from the sun) will generate heat in the battery which is yet another reason not to fast charge.