Battery Charger Device for Multiple Applications

Overview

The project has a rating of 24Wh as the energy stored using 11 NiMh AA cells to be used for charging a laptop, satellite phone, camera battery, and mobile phones.

Explanation

The device has a cunning design wherein some of the AA cells can be removed from the internal battery stack and be exchanged with flat ones. A DC supply in the range of 10V to 30V or a 5W solar panel can be used to charge the battery stack. The LCD is used to display the status of internal batteries and the amount of incoming and outgoing power. A timer can be set for the battery charger and various outputs can also be switch ON/OFF.

The current through the batteries can be monitored using an oscilloscope wherein a series of pulses can be found at the frequency of the dynamo. Either the dynamo via a bridge rectifier and a current limit or a solar panel also via a current limit can be used to charge the AA cells. A normally closed relay is used as the current limit since it provides zero-resistance current path. Opening the relay forces the current to flow.