Abstract: The technology relates to managing nighttime power for solar-powered vehicles. A system may include a sunrise estimator for estimating a time until a next sunrise, a battery state estimator for estimating a battery state, a critical battery estimator for determining a battery threshold, below which subsystems may be powered off, and an alert monitor to determine, and communicate to the solar-powered vehicle, a charge threshold and a restart charge threshold. A method may include operating a vehicle in an operational power mode, estimating a time until a next sunrise, estimating a battery state, determining a preservation battery threshold based on the estimated time until the next sunrise and the estimated battery state, determining a minimum charge threshold based on the preservation battery threshold, monitoring a battery charge level of the vehicle throughout the night, and if the battery charge level drops below the minimum charge threshold, implementing a preservation power mode.

Abstract: The technology relates to power saving modes for subsystems in solar powered aircraft. An onboard subsystem of an aircraft includes a first processor configured to monitor a state of the subsystem and generate state data; a heating component configured to heat the subsystem to at least a minimum viable temperature; an operational component; and a hardware controller configured to control power to the heating component, the first processor, and the operational component, at least during a preservation mode and a monitoring mode. The subsystem draws a moderate amount of power when the heating component is on and a minimum threshold amount of power in the preservation mode. The subsystem draws a moderate amount of power in the monitoring mode in order to generate and communicate state data by the first processor, a moderate amount of power being lower than the higher amount of power required to operate the operational component.