Each of the batteries goes through high- and low-drain tests to assess how they perform in different gadgets. We average the results from four examples of each model in every test.
In each of the high- and low-drain tests, we measure how long the batteries last (endurance) under a fixed load, and the amount of energy they deliver over that time.
A load of 24 Ohms is used for the low-drain test, while the high-drain test has a load of 2 Ohms.
Endurance is measured in hours and minutes from each battery’s starting voltage of 1.5V down to 1.0V then to 0.7V. Some devices start to falter or won’t operate at 1.0V. We use 0.7V as our benchmark for the batteries being completely empty.
We then convert the measurements into high- and low-drain performance scores, giving equal weighting to endurance and energy. An overall score is then assigned based equally on performance in the high- and low-drain tests.
We've tested 13 batteries.
Find the right one for you.