How to store power tool batteries in a cold shed or van

What cold does to lithium batteries

Cold slows the chemistry inside lithium-ion cells. A cold pack delivers less runtime and may cut out under heavy load, such as a circular saw. Performance recovers as the pack warms. Using a cold pack is generally fine; charging it is the problem.

Charging lithium cells below about freezing can damage them, so tool chargers pause or refuse until the pack is warm enough. That is the hot or cold delay many chargers show. See charger lights flashing.

The best place to store packs

Indoors, at normal room temperature, dry, and away from direct heat such as radiators. A cupboard in the house or a heated workshop is ideal. Avoid leaving packs in an unheated shed, garage or van overnight in winter, or in a hot van or car in summer.

Keep packs off concrete floors where damp can condense, and away from metal objects that could short the terminals. Fit the terminal covers if your packs came with them.

• Room temperature, dry and out of sunlight.
• Away from radiators, heaters and flammable materials.
• Terminals covered or kept clear of metal.
• Out of reach of children.

Charge level for storage

For storage of more than a few weeks, many battery makers advise keeping lithium packs part charged rather than full or empty; around half charge is a common recommendation. Storing packs fully charged in warm conditions ages them faster, and storing them completely flat risks them dropping too low for the charger to accept.

Check packs every couple of months and top them up if the gauge has fallen. Always follow your tool maker's storage advice in the manual.

Working in the cold

On cold days, keep spare packs in the cab or a bag inside your coat rather than in an open van. Swap packs more often, and let a pack rest if a tool cuts out. Large packs tend to cope better with high loads in the cold. Bring everything indoors at the end of the day.

Battery runtime also falls as packs age. If a pack that used to last a morning now struggles, it may be reaching the end of its life.

Warming a cold pack safely

Let it warm naturally indoors. Do not put batteries on radiators, in ovens or microwaves, near heaters or in direct sunlight to speed things up. Once it reaches room temperature, the charger should start normally.

Note:Never charge a battery that is below freezing, swollen, damaged or wet. Charge on a hard, non flammable surface and do not leave packs charging unattended for long periods. Follow the maker's manual and recycle damaged packs.

Garden tool batteries over winter

Many people use the same 18 V packs for mowers and hedge trimmers that sit unused all winter. Clean the tools, remove the batteries, part charge them and keep them indoors. In spring, charge fully before the first cut. If you are choosing a platform for house and garden, read how to choose a battery platform and see bundles in our power tool kit guide.

Understanding the numbers

Bigger packs store more energy and are better for cold weather work under heavy load. Learn how to compare them in volts, amp hours and watt hours. Our combi drill kit guide shows which kits include larger packs.

Frequently asked questions

Can I leave batteries in a shed over winter? It is better not to. Cold, damp and frost can shorten battery life and cause charging problems. Bring them indoors.

Why will my charger not charge a cold battery? Chargers pause charging below a safe temperature to protect the cells. Let the pack warm to room temperature.

Should I store batteries fully charged? For long periods, part charged is usually recommended. Check your maker's guidance.

Is it OK to use a cold battery? Generally yes, though runtime and power are lower until it warms. Do not charge it while cold.