Battery management systems are simple in theory. Using a current monitor, only put as much current
back into the battery as you take out. Instead of maintaining a constant 13.8 volts (V) or thereabouts, a battery
management system checks the battery’s state-of-charge (SOC) when the engine is off and when current flow is
essentially zero. From then on it will target a SOC of 100 percent or less in order to save fuel, avoid
overcharging and extend the life of the battery.