In an embodiment, an auxiliary-power-supply unit includes a connector and a controller configured to power a microgrid from a battery in response to determining that the connector is plugged into an outlet of the microgrid, and that the microgrid is uncoupled from a power grid. For example, the connector plugs into a wall outlet of a microgrid in, e.g., a home, and provides, from the battery during a power outage, auxiliary power to the microgrid and, therefore, provides auxiliary power to one or more devices, such as appliances, lights, computers, or televisions, that are connected to the microgrid.