At the supermarket, we look at the price/kg or price/l when comparing similar products. But we can’t really do that when it comes to getting an AA battery. For getting those, people usually go for names they are familiar with, such as Duracell or Panasonic, or go after attractive terms such as ‘PLUS’, ‘SUPER’ or ‘MAX’. But Denis Hennessy had other ideas. He bought a pack of every AA battery type he could find to do an experiment to see which brand provides the most bang for the buck.
Hennessy had an Arduino and an LCD panel, and he designed a circuit which allowed him to measure how much energy each battery produced. He also added a temperature sensor and USB logging capability. The circuit measured the voltage across a fixed load every second until the battery reached 0.2V, while the LCD displayed voltage and the amount of energy generated, in Joules and watt-hours. With the data collected, Hennessy compared each of the batteries in terms of the cost per Watt-Hour.
And the result revealed that super charged names such as ‘super’ and ‘max’ don’t really mean much. The best performance was from RS Power Ultra, and the worst from the Panasonic Evolta.