Think of the battery in terms of the fuel in your gas tank. As you get low on fuel you have a reserve to alert you to your fuel level and prevent you from running out of gas. Batteries and the battery management systems are designed the same way to prevent you from discharging the batteries to a low state of charge (SOC) which would reduce the life of the product.
The total energy of a system (rated energy) can be misleading since you can only use a portion of the battery’s energy during operation. The useable energy of a battery is the range at which the battery can operated over a SOC range. 100% SOC means your battery is 100% charged. When you are applying a load to your battery the result is the depth of discharge (DOD) of the battery.
SOC of 100% and DOD of 100% are avoided to maximize the battery life. In some chemistries such as lead acid (PbA) going below 50% DOD will drastically reduce the battery life due to the side reactions that occur on the anode and cathode of that battery while in that state. Li Ion technology can operate at lower SOC without impacting the life of the battery.
Volta Power Systems provides an energy storage solution where 90% of the battery’s energy is usable vs that of a lead acid AGM system where only 50% of the energy is usable despite the increase in space and weight. Ultimately higher useable energy means greater battery utilization and cost giving you the best lifetime cost.