The overall Which? test score is made up of the following star ratings, all determined by our rigorous lab tests.
How we test long-term use
This score indicates how well the battery maintains its capacity over hundreds of uses in very high-drain conditions, taking into account the total battery life it gives during this time. Scores for 80% and 60% capacity show for how many recharges the battery maintains at least this percentage of its initial capacity. For 80%, for AA and AAA batteries, ***** indicates the battery could reach at least 80% capacity after more than 150 uses, * indicates that after fewer than 50 uses it couldn’t reach 80% capacity any more. For 60%, for AA and AAA batteries, ***** indicates the battery could reach at least 60% capacity after more than 180 uses, * indicates that after fewer than 90 uses, it couldn’t reach 60% capacity any more.
How we test battery life on a single charge
The average lifetime per recharge in a power-hungry device. We test batteries in high-drain conditions and measure how long they last until they are discharged to the point that they won’t work in a device.
How we test charge retention
How well the batteries retain their charge after 25 and 50 days when not in use.
How we test stated capacity achieved
We measure the capacity (in mAh) achieved by the battery, using a smart charger, and compare this with the minimum capacity stated by the manufacturer on the packaging.
How we test time to charge
How long the batteries took to charge in our charger, using the soft-charge setting. For AA batteries: five stars is under four hours, four stars is four to five hours, three stars is five to six hours, and two stars is six to seven hours. For AAA batteries: five stars is less than 1 hr 55 min, four stars is 1 hr 56 min to 2 hr 5 min, three stars is 2 hr and 6 min to 2 hr 25 min, two stars is 2 hr 26 min to 2 hr 45 min.
