How to Store Power Tool Batteries

You reach for your cordless drill, pull the trigger, and nothing happens. The battery that worked last month is flat, or it no longer holds a charge the way it used to. How a lithium-ion pack is stored between jobs is one of the few things you control, and the manufacturers’ own manuals are specific about it: Milwaukee warns that permanent capacity loss can result when a pack is stored for long periods at high temperatures (over 120°F).

This guide pulls together what battery makers, Battery University and fire-safety agencies say about charge level, temperature, location, seasonal storage and warning signs, so you can set up a simple routine and know when a pack should be retired instead of stored.

TL;DR Quick Answer: Store Power Tool Batteries

Storage checklist:

• 🔋 Charge level: follow your brand’s manual. Battery University notes that Li-ion has higher losses if stored fully charged rather than at about 40 percent, while DEWALT recommends storing a fully charged pack out of the charger for long storage.
• 🌡️ Temperature: store lithium-ion batteries at room temperature when possible (U.S. Fire Administration).
• 🔥 Heat limit: Milwaukee says not to store a pack where temperatures may exceed 120°F (50°C); DEWALT’s limit is 104°F (40°C).
• 💧 Dry: avoid damp locations where terminals can corrode.
• 🔩 Terminals: keep metal objects away from exposed battery terminals.

Why Battery Storage Actually Matters

Lithium-ion packs age even when they sit on a shelf, and storage conditions change how quickly that happens. Battery University gives 15°C (59°F) as the recommended storage temperature for most batteries, and notes that Li-ion has higher losses if stored fully charged rather than at a state of charge of 40 percent.

Heat is the condition tool makers warn about most directly. Milwaukee’s manual states that permanent capacity loss can result if a pack is stored for long periods of time at high temperatures (over 120°F), and DEWALT tells owners that for best life, battery packs should be stored in a cool, dry location.

Storage is also a fire-safety question. The NFPA points out that these batteries store a large amount of energy in a small space and that a small number are defective and can overheat, catch fire or explode, so where you keep them matters as much as how full they are.

For more on how long packs last in use, see our guide on how long cordless drill batteries last.

The Golden Rules of Battery Storage

Three factors decide most of what happens to a pack in storage: its charge level, the temperature around it and the place you keep it.

Rule 1: Charge Level (Follow Your Brand’s Manual)

There is no single number every manufacturer agrees on. Battery chemistry references and tool manuals phrase this differently, so start with the manual for your battery platform.

• Battery University: Li-ion has higher losses if stored fully charged rather than at a state of charge of 40 percent, and finding the exact 40–50 percent level is not that important.
• DEWALT: for long storage, it recommends storing a fully charged battery pack in a cool, dry place out of the charger.
• Milwaukee: its Li-Ion packs maintain their charge during storage, and after about a year of storage you should charge the pack as normal.

A practical approach: store packs the way your brand’s manual describes, and do not leave a pack completely empty for months. Most packs have a fuel gauge, so you can check the level before putting a pack away.

Rule 2: Temperature (Cool, Never Hot)

Heat is the main enemy in storage. The U.S. Fire Administration advises storing lithium-ion batteries at room temperature when possible, and Battery University lists 15°C (59°F) as the recommended storage temperature for most batteries.

Manufacturers set hard upper limits. Milwaukee says not to store a pack where temperatures may exceed 120°F (50°C), such as in direct sunlight, a vehicle or a metal building during the summer. DEWALT’s manual says not to store or use the tool and battery pack where the temperature may reach or exceed 104°F (40°C), such as outside sheds or metal buildings in summer.

Cold matters most when you charge. Makita’s DC18RC charger manual says not to charge a battery cartridge when room temperature is below 10°C (50°F) or above 40°C (104°F), and the NFPA’s general advice is not to charge lithium-ion batteries below 32°F (0°C) or above 105°F (40°C).

Rule 3: Location (Dry, Safe, Organized)

Where you store matters as much as how you store.

Milwaukee says to store battery packs away from moisture and not in damp locations where corrosion of terminals may occur. Loose metal is a short-circuit risk: DEWALT warns not to store or carry a pack so that metal objects can contact exposed battery terminals, and Milwaukee cautions that a short-circuited pack may cause fire and personal injury. The NFPA also advises storing batteries away from anything that can catch fire.

A sensible storage setup:

• The original hard case, a dedicated battery organizer or a shelf where packs sit on their own
• An indoor space that stays close to room temperature
• Away from windows, heaters and anything flammable
• No screws, nails, coins or other loose metal in the same container
• A label or note with the date the pack went into storage

Step-by-Step Storage Process

Before Storing

1. Check the charge level on the pack’s fuel gauge and adjust it to what your manual recommends.
2. Keep the pack clean and dry. Milwaukee says not to use oil or solvents to clean or lubricate a battery pack, because the plastic casing can become brittle and crack.
3. Inspect for damage. The Battery Network defines damaged or defective batteries as any battery that is swollen, leaking, punctured or overheating; a pack like that should not go back on the shelf.
4. Note the date on a label or in your phone.

Where to Store

What to Avoid

• ❌ Storing in direct sunlight, a vehicle or a metal building in summer (Milwaukee)
• ❌ Tossing packs in a drawer where metal objects can touch the terminals (DEWALT)
• ❌ Letting packs get wet or storing them in damp areas (Milwaukee)
• ❌ Storing a pack inside a tool with the trigger switch locked on (DEWALT)
• ❌ Putting a cracked, swollen or leaking pack back into storage

Seasonal Storage Guide

Winter Storage (Cold Weather)

An unheated garage or shed can get very cold in winter. The bigger issue is charging a cold pack: Makita says not to charge when room temperature is below 10°C (50°F), and DEWALT chargers that detect a pack that is too hot or too cold start a Hot/Cold Pack Delay, suspending charging until the pack reaches an appropriate temperature.

What to do:

• Bring packs indoors for the winter if your workshop is unheated.
• Let a cold pack warm up indoors before charging it.
• Keep packs dry when moving them between a cold space and a warm room.

Summer Storage (Hot Weather)

Summer heat is when storage mistakes are most likely. DEWALT names outside sheds and metal buildings in summer as places that may reach or exceed 104°F (40°C), and Milwaukee lists direct sunlight, a vehicle or a metal building during the summer as places where temperatures may exceed 120°F.

What to do:

• Move packs to the coolest indoor space you have.
• Don’t leave batteries in a car or truck between jobs.
• Let a hot pack cool before charging; Makita says not to charge above 40°C (104°F) room temperature.
• Check for swelling or a warped case before putting a pack away.

Long-Term Storage (Off-Season)

1. Set the charge level your brand’s manual recommends.
2. Store the pack indoors, dry and away from heat sources.
3. Keep terminals covered or away from metal objects.
4. For Milwaukee packs, charge as normal after about a year of storage; for other brands, follow the manual.
5. Charge fully before the next job.

Common Storage Mistakes (And How to Avoid Them)

Mistake 1: Storing Packs Somewhere Hot

The scenario: Batteries live in the truck, in a metal shed or on a sunny shelf.

The reality: Milwaukee states that permanent capacity loss can result if a pack is stored for long periods at high temperatures (over 120°F).

The fix: Keep packs indoors in a cool, dry place.

Mistake 2: Ignoring Your Manual on Charge Level

The scenario: You follow a generic rule you read online instead of the instructions for your battery platform.

The reality: Guidance differs. Battery University says Li-ion has higher losses if stored fully charged rather than at 40 percent, while DEWALT recommends a fully charged pack stored out of the charger for long storage.

The fix: Use your manufacturer’s instructions; they cover the pack and charger you actually own.

Mistake 3: Loose Batteries Among Metal Parts

The scenario: Spare packs go into a bucket or drawer with screws, nails and bits.

The reality: Milwaukee warns not to place a pack near anything that may cause a short circuit, such as coins, keys or nails, because a short-circuited pack may cause fire and personal injury.

The fix: Give batteries their own case, shelf or organizer.

Mistake 4: Storing a Damaged Pack

The scenario: A pack with a cracked case or a slight bulge goes back on the shelf “for later.”

The reality: The Battery Network warns that damaged or defective batteries can spark or ignite if stored or transported improperly.

The fix: Stop using it and recycle it safely (see below).

Battery Storage Products Worth Considering

You don’t need much, but the right accessories help.

Battery Organizers and Hard Cases

A dedicated case or wall mount keeps packs off the floor, away from loose metal and easy to inspect. Many tool brands sell cases and mounts sized for their own batteries; check that a mount fits your pack’s rail or slide design before buying.

Thermometer or Thermometer/Hygrometer

An inexpensive thermometer that records high and low readings shows whether a garage or shed stays within the limits in your manual through the seasons.

Budget Option: Original Packaging

If your batteries came in a hard case, use it. If they came in cardboard, a plastic organizer with separate slots is a simple upgrade.

For a broader routine that covers tools as well as batteries, see how to create a power tool maintenance routine that works.

Battery Safety Warning Signs

Stop using a battery immediately if you notice any of these. The NFPA lists odor, change in color, too much heat, change in shape, leaking or odd noises as signs to stop using a lithium-ion battery:

• 🔴 Swelling, bulging or a warped case
• 🔴 Cracks in the casing
• 🔴 Leaking fluid
• 🔴 Unusual smell
• 🔴 Too much heat
• 🔴 Odd noises

What to do with a damaged pack:

• If the battery case is cracked or damaged, do not insert it into the charger (DEWALT).
• If it is safe to do so, move the device away from anything that can catch fire, then call 9-1-1 (NFPA).
• Isolate the battery and place it in non-flammable material such as sand or kitty litter (The Battery Network).
• Never put damaged batteries in the trash, water, home recycling bins or The Battery Network’s regular collection boxes; there may be trained drop-off locations near you that can accept them.
• Do not incinerate a battery pack, even if it is severely damaged or completely worn out (DEWALT).

Recycling Old or Worn-Out Packs

The EPA says lithium-ion batteries and devices containing them should not go in household garbage or recycling bins. To prevent fires, it recommends taping battery terminals and/or placing lithium-ion batteries in separate plastic bags before taking them to a battery recycling location.

Quick Reference: Battery Storage Cheat Sheet

FAQ

How long can power tool batteries sit unused?

It depends on the brand. Milwaukee says its Li-Ion packs maintain their charge during storage and that after about a year of storage you should charge the pack as normal. For other brands, check the maintenance and storage section of the manual.

Can I store batteries in the garage?

Only if the garage stays dry and does not get hot. DEWALT says not to store packs where the temperature may reach or exceed 104°F (40°C), which rules out many uninsulated garages and sheds in summer. If yours gets hot or damp, bring batteries indoors.

Should I store my battery fully charged or half charged?

Follow your manufacturer. DEWALT recommends storing a fully charged pack out of the charger for long storage, while Battery University’s general guidance is that Li-ion loses more when stored fully charged than at about 40 percent.

Can I leave a battery on the charger?

Check your charger’s manual. DEWALT’s DCB112 manual says a fully charged pack may be used or left in the charger, but recommends storing packs out of the charger for long storage. The NFPA’s general consumer tip is not to keep charging a device battery after it is fully charged.

How do I know if my battery is damaged?

The Battery Network treats any battery that is swollen, leaking, punctured or overheating as damaged or defective. Stop using it and follow the damaged-battery steps above.

Is it okay to store batteries in the refrigerator?

That is not what manufacturers describe. Milwaukee’s instructions are to store packs at room temperature away from moisture, and DEWALT’s are a cool, dry location.

Bottom Line

Proper battery storage isn’t complicated. Keep packs indoors, dry and away from heat; keep terminals away from metal; set the charge level your manufacturer recommends; and retire any pack that is swollen, cracked, leaking or overheating.

Key takeaways:

• Your battery manual is the authority on storage charge level
• Store lithium-ion batteries at room temperature when possible
• Never store packs in vehicles, direct sunlight or hot sheds
• Give batteries their own case, away from loose metal
• Recycle worn-out packs instead of putting them in the trash