Lithium Ion is starting to revolutionise energy. In the past we thought of a battery being a dirty, smelly, corrosive box. Don't touch it otherwise you will get acid on you hands and holes in your clothes.
Now we look at batteries as a box of energy.
This is a 12 volt 300mm case producing 120amp. 4 cells adding up close to 16 volts when fully charged and all balanced.
A 12 volt battery is 14.2 volts when fully charged.
On top of the battery is what is called BMS or Battery Management System. This is the brains of the battery keeping the battery safe.
Some of the functions or brains the BMS does.
Monitor- Voltage,Temperature, State of Charge, State of Health.
Calculate- charge current limit, discharge current limit, open circuit voltage each cell, charge delivered and stored, total energy delivered since first use, total number of cycles