Tap and hit them. The simplest way possible. It doesn’t sound effective but mechanical influence can actually be very helpful – it prolongs battery time for about 2-3 days. That’s why you should try slightly hitting the battery with a small hammer or knock two batteries against each other. Basically, any physical impact can bring the battery back to life. One more option – carefully use pliers to press on the battery.
Heat them up. This is a scientifically proven fact – heating up AA batteries can restore its functionality. This, by the way, also applies to mobile device batteries but that’s not something we recommend to do. Anyway, try immersing your AA batteries into hot water for about 20 minutes or putting them on a radiator. Both ways give you extra time to use these batteries.
Open them up. The most difficult but relatively safe way. You need to make two holes beside each carbon rod and use a syringe to pour a certain liquid in there. Speaking of liquid, you can use either 8- or 10-percent hydrochloric acid solution or vinegar. After that, the holes can be covered with wax or playdough.
Remember that all these ways don’t guarantee success. Even if a battery starts working again, it won’t last for a long time. These tips can be useful but better to have some extra batteries for quick and safe replacement.