Solar-powered radios primarily offer three charging methods: solar charging, hand-cranking, and USB/AC power charging; the specific options available depend on the model.
Solar Charging: Place the radio in direct sunlight with the solar panel facing upward; light energy is converted into electricity to charge the built-in battery. This is the primary charging method, though it is relatively slow, typically requiring several hours for a full charge. For instance, a model with a built-in 750mAh battery takes about 7 hours to fully charge under peak sunlight.
Hand-Cranking: Many emergency radios feature a hand crank that generates power when turned, making it ideal for emergency top-ups when sunlight is unavailable. For example, with the Sony ICF-B99, cranking the handle for one minute provides approximately 30 minutes of listening time.
USB/AC Power Charging: Charging via a cable connected to a computer USB port or a power adapter is the fastest method and the most convenient way to recharge during daily use.