As we have learned, battery voltage is the missing link that allows us for direct comparison between a set of battery systems. But the most important specification for your application will always be the rated energy. Jolien Despeghel Jeroen Tant
The first important parameters are the voltage and capacity ratings of the battery. Every battery comes with a certain voltage and capacity rating. As briefly discussed earlier, there are cells inside each battery that form the voltage level, and that battery rated voltage is the nominal voltage at which the battery is supposed to operate.
Capacity ratings only tell you how much energy the cell can store and provide. They don’t give you any information about the power of the cell or its longevity. The highest capacity batteries usually have only moderate power levels. There is often a tradeoff between power rating and capacity.
Summarized below are some of the key technical terms used in battery specifications: Nominal Voltage (V) This is the reference voltage of the battery, also sometimes thought of as the “normal” voltage of the battery. Cut-off Voltage (V) This is the minimum allowable voltage of a battery.
Power capacity is how much energy is stored in the battery. This power is often expressed in Watt-hours (the symbol Wh). A Watt-hour is the voltage (V) that the battery provides multiplied by how much current (Amps) the battery can provide for some amount of time (generally in hours). Voltage * Amps * hours = Wh.
(Recommended) Charge Current – The ideal current at which the battery is initially charged (to roughly 70 percent SOC) under constant charging scheme before transitioning into constant voltage charging. (Maximum) Internal Resistance – The resistance within the battery, generally different for charging and discharging.