TESTING POWER

“Air batteries have the potential to revolutionise portable energy”

The test strips on batteries have three layers of ink. On top there’s a heat-reactive ink that turns from black to clear when it gets warm. In the middle there’s a coloured ink and on the bottom there’s conductive ink that gets hot when a current passes through. That bottom layer is thinner at one end than the other, which means that it only gets hot when the current is high. When the battery is full, it generates enough electricity to reveal the whole test strip. As it starts to empty, less of the bar shows through.

Battery test strips use conductive and heatreactive inks

Recycling plants break batteries apart so that the chemicals inside can be reused