The most common way to charge your lifeless rechargeable AAA batteries is to purchase an AAA battery charger. This is not always an available option. There are other methods to use in a pinch if you lost, or do not have a battery charger.
One way to recharge old alkaline batteries you do not use around the house anymore is with lemon juice. Lemon juice contains acids that will get the electrons flowing in the battery again. It can restore up to 85 percent of a battery’s energy. Submerge your dead AAA battery in 1 cup of lemon juice for about an hour.
Putting your batteries into plastic bags in the freezer will not recharge them. This is a common misconception. It can, however, help to preserve the shelf life of a battery before use. Alkaline batteries will on average gain about 5 percent more power over time if stored in a freezer. The problem occurs when you need to make immediate use of a frozen battery. Batteries must be warmed to room temperature to function properly. So, you will always want to have a number of unfrozen batteries on hand. Once a battery is dead, the freezer will not recharge it.