An electrical system can include a power supply that provides primary power, and a light fixture having at least one light source, where the light fixture is coupled to the power supply, where the at least one light source illuminates when the light fixture receives the primary power. The electrical system can further include an energy storage unit having at least one energy storage device that charges using the primary power. The electrical system can also include a controller that determines an initial charging period during which the at least one energy storage device is charged using a constant supply of the primary power, where the controller changes the constant supply of the primary power to a trickle charge of the primary power at the end of the initial charging period to maintain a minimum charge level of the at least one energy storage device.