TescoExtra Long Life AA

How we test high-drain battery life rating

We test batteries in high, medium and low-drain conditions (to represent the range of devices you use them in). High-drain equates to remote-controlled toys, medium-drain to games console handsets or portable radios, and low-drain to clocks. We measure how long batteries last until they are drained to the point where most appliances stop working (1V), and to the point when all appliances stop working (end voltage, 0.8V). Star ratings are based on a combination of how long the batteries last in both our 1V and end voltage tests.

How we test energy efficiency

This is a comparative rating for the total energy contained within the battery. It indicates how well the battery is likely to power your device, however power-hungry it is, compared with others on test.