Cordless power tool batteries are the most efficient when they are used regularly but, if you need to store them, follow these tips.
Batteries, chargers and cordless power tools should be stored separately, not fitted together.
Batteries and chargers need to be stored in a dry place out of direct sunlight and preferably at room temperature (15-21 degrees Celsius) but definitely not at any temperature extremes (below about 4 degrees Celsius and above 40 degrees Celsius).
You might hear rumours that storing your battery in the freezer is good for it but Wonkee Donkee doesn’t advise this. Freezing your battery can permanently damage it.
The box or padded carrying case you purchased them in will protect them from dust and damage but an airtight container can be better because it doesn’t let condensation get into the battery cells.
Do not store your battery in a place with any conductive materials like small metal objects such as paper clips or nails. If they touch the contacts and connect them together, they can short circuit the battery, severely damaging it.
Some batteries and chargers come with a protective plastic cover which fits over the contacts and prevents them getting damaged during storage.
Chargers should be stored unplugged with the power lead untangled, coiled and without any major weight on it. Use the plug to unplug the charger – avoid pulling on the power lead as it can damage the connections in the plug.
NiCd batteries must be stored at 40% or more charge to avoid over discharge through self-discharging during storage. This is best for NiMH batteries too. Li-ion batteries can be stored at any charge level without damage.
During long-term storage, Li-ion batteries should be recharged every 6 months and nickel-based batteries should be discharged and recharged once a month (one charge cycle) to prevent permanent damage through over-discharge.
Nickel-based batteries may need to be primed (conditioned) before use, after a long storage, to redistribute the electrolyte and optimise the battery capacity (see How to prime a nickel-based cordless power tool battery).
Depending on how long they have been stored for, Li-ion batteries will usually have retained some of their charge and can be used straight from the shelf or recharged in the normal fashion.
