Ever been in a situation where you had tried to figure out if your batteries had charge or not? Did you ever want to find out the capacity of a battery? This article would help you to design a circuit that would measure the capacity of a battery.
The purpose of this project is to design a simple circuit that would measure the energy produced by a battery as it is being discharged. An Arduino and an LCD panel form the core components of the circuit. The circuit, apart from measuring the battery capacity can also be used for temperature measurement and data logging.
The circuit works in a very simple way. Voltage is measured across a fixed load every second every second until it drops to a values less than 0.2V. To make the design simple, a 4.7R resistor is used.
A case with cutouts and standoffs is used for the Arduino and the LCD. A small bit of strip board is added support the extra components. A USB connection powers the entire circuit. The load resistors drain the entire charge from the batteries.
The units starts to work once a battery is connected to the circuit. The moment a battery is detected in the circuit, the temperature and voltage is measured once every second and the cumulative energy is displayed in Joules and Watt-Hours. The readings are recorded in the USB port once a second and the values are written to a csv file. The circuit stops working once the voltage falls to under 0.2V.
Click here to visit the project page.