When we buy (rechargeable) batteries, it's mostly with the intention to use them as long as possible. Battery care and battery storage is therefore essential to extend the lifetime of the batteries. But where do you need to store your (rechargeable) batteries when you're not using them?
When storing your batteries, keep in mind the temperature can't be extreme. The recommendation says batteries need to be stored around 15°C. Keep your batteries away from the sun and choose any cool and dry room for the storage. A battery loses charge capacity when temperatures are extreme. Keep in mind that batteries self-discharge when they're in storage. But eneloop rechargeable batteries keep 70% of their capacity even after 10 years of storage.
Next to the temperature, the types of batteries are also important when storing batteries. Make sure you separate them by make and age. Batteries from different manufacturers can start leaking, cause damage or can react with each other.
If you buy new (rechargeable) batteries, but you're not immediately using them, keep them in the original packaging. This prevents that the batteries come into contact with other metals. Do not store your batteries in metal containers, use a plastic one or a battery box. Avoid coins or other metals in the same box. If you can't guarantee the positive terminals won't be in contact with the negative ones, then use tape or plastic caps to cover the terminals. If batteries come in contact with metals, they can start conducting electricity.
Always check the charging level before the battery storage. Use separate containers to keep new and used batteries apart. The Nickel-based batteries (like the eneloop batteries) can be stored at any state of charge. The Lithium Ion ones must be stored at 30-50% maximum charge for the best results. But it's better to store when they are fully charged when you're not going to recharge in a few months.
Too high humidity is bad for the storage of batteries. A vapor-proof container is an option to keep them away from a high humidity environment. The perfect humidity is 35% to 65%. Never put your batteries in the freezer unless it's recommended by the manufacturer. The condensation in the fridge can cause damage inside the battery. Keep these factors in mind next time you start with the battery storage.