Abstract: A portable solar battery charger comprises a photovoltaic array, a power regulator, a controller, and a battery. In one embodiment, the controller is configured to increase the charging current provided by the power regulator to the battery over time using discrete current levels. A comparator can compare the voltage of the photovoltaic array to a threshold, and provide the result to the controller. The controller can be configured to decrease the current to a previously selected level when the comparator indicates the voltage of the photovoltaic array is below a threshold, thereby improving the efficiency of the current delivery to the battery.

Abstract: A solar chargeable battery comprises a built-in photovoltaic array and a programmable battery charging circuit. The photovoltaic array provides a variable power source in response to light. The battery charging circuit receives the variable power source and operates in different modes to charge the battery over a range of lighting conditions. For example, the battery charging circuit charges the battery to a substantially fixed regulated voltage level in a first mode when a voltage level of the variable power source is above a predefined threshold. The battery charging circuit charges the battery to an adjustable regulated voltage level in a second mode when the voltage level of the variable power source is below the predefined threshold.

Abstract: A portable solar battery charger comprises a photovoltaic array, a power regulator, a controller, and a battery. In one embodiment, the controller is configured to increase the charging current provided by the power regulator to the battery over time using discrete current levels. A comparator can compare the voltage of the photovoltaic array to a threshold, and provide the result to the controller. The controller can be configured to decrease the current to a previously selected level when the comparator indicates the voltage of the photovoltaic array is below a threshold, thereby improving the efficiency of the current delivery to the battery.

Abstract: A solar chargeable battery comprises a built-in photovoltaic array and a programmable battery charging circuit. The photovoltaic array provides a variable power source in response to light. The battery charging circuit receives the variable power source and operates in different modes to charge the battery over a range of lighting conditions. For example, the battery charging circuit charges the battery to a substantially fixed regulated voltage level in a first mode when a voltage level of the variable power source is above a predefined threshold. The battery charging circuit charges the battery to an adjustable regulated voltage level in a second mode when the voltage level of the variable power source is below the predefined threshold.