12v batteries are rated to be charged at 12v or a maximum of 14 volts depending on the type of battery and its state of charge. A fully drained battery will accept higher voltage but as the battery will g.
[pdf] Solar panels can charge lithium batteries, but an MPPT solar charge controller is required. More current goes into the battery when an MPPT controller is used, which leads to faster battery charging. This is a step by step guide to charging lithium batteries with solar panels.
[pdf] What batteries are used in energy storage cabinets? Energy storage cabinets utilize various types of batteries, including 1. Lithium-ion batteries, 2. Lead-acid batteries, 3. Nickel-cadmium batteries, 4. Flow batteries.
[pdf] 
