Resiliency Tip #005

Rechargable Battery Storage and Rotation

Something to consider when storing rechargable batteries for power tools or other applications is to not store your batteries fully charged. Lithium Ion chemistry in particualr does not like to be at a max voltage or low voltage states for long periods of time, and storing your batteries after fully charging them will actually shorten the lifspan of your batteries when done repeatedly, or even only once, as will storing them depleted. Instead, partially charge your batteries before long storage of more than a day without planned use. Ideally a charge between 40-80% is where lithium ion prefers to sit for long term.

Batteries also discharge slowly over time whether they are hooked up or not. Any batteries which are in storage should be checked regulary and charged to the ideal percentage if they drop below a 40% charge. A good maintenace plan is to check your rechargeable batteries every 3-6 months and charge as needed. This will keep them healthy so that in the case of an emergency, especially a prolonged one. They will serve you especially when replacements are not readily acquired or available.

Also, if you have multiple batteries of the same type or application, rotate your batteries with those in storage to ensure an even distribution of life between all your batteries. An easy way to track your batteries, is to simply put some painters tape on them and Mark the last charge time and charge length or percentage on the battery before putting in storage. This will make it easier to track which batteries should be rotated out next.

Consider an outlet timer in addition to your charger to control the length of time you charge your batteries for. Because charging is a passive action, if you set your timer to say 15 mins, and you get distracted you won't have to worry about overcharging them for storage.

While the examples above mainly reference power tool batteries, this can be utilized for any types of chemical batteries or appliances, for example radios/comm equipment, laptops, torches/flashlights, power bricks, e-bikes, ect...

Lastly be intentional about your appliance/battery type selection. The more overlap between battery types/sizes/chargers among your equipment the better. Having a standard allows for easier tracking and maintenance, as well as having the advantage of being able to power more things with less clutter and complexity. Some things may have adapters available for cross platform use, however be cautious as batteries are explosive and if adapted improperly might burn your house down.