How to Store and Care for Cordless Tool Batteries

Store lithium-ion tool batteries in a cool, dry place at about half charge, charge them at normal room temperature and let a hot pack cool first. Avoid freezing and heat, don’t repeatedly run a pack completely flat, and use the charger that came with that battery. A pack usually lasts several years, and a swollen, leaking or badly weakened pack should be replaced.

Care rules at a glance

Situation	Do this	Why
Storing for weeks or months	Cool, dry place, about half charge	Full charge and heat both age the cells faster
Hot pack after hard use	Let it cool before charging	Charging hot cells shortens life
Cold garage in winter	Bring the battery indoors before charging	Charging cold cells can damage them
Regular use	Charge when the pack is low, before it is completely flat	Deep discharges strain the cells
Shipping or carrying	Keep terminals covered or in the case	Metal objects can short the contacts

Makers publish exact temperature ranges in the battery’s manual, so check them for your platform.

How to charge a tool battery

1. Use only the charger for that battery and platform. Chargers are matched to their own packs; see are drill batteries interchangeable.
2. Let a hot battery cool for a few minutes before putting it on the charger.
3. Charge at room temperature, on a hard surface, away from flammable materials.
4. Take it off the charger when the light shows full, if you will not use it soon.
5. Don’t charge a damaged battery.

If a battery will not charge because it has gone flat, see how to charge a drill battery without a charger for what is safe and what is not.

How to store batteries

• Keep them in a dry place at room temperature, away from direct sun and heat.
• For storage of a month or more, leave them at roughly half charge, and check them every few months.
• Store them off the tool, with covered terminals or in the case.
• Don’t store loose batteries in a drawer with screws or keys that can touch the contacts.

How long do tool batteries last?

Battery life is counted in charge cycles. Lithium-ion tool packs commonly last several hundred cycles, which for many homeowners is a few years. Heat, deep discharge and long storage at full charge shorten it. Larger packs in amp-hours (Ah) last longer between charges, but they age the same way; see cordless drill voltage and amp-hours.

When to replace a battery

Replace a battery when:

• it swells, leaks, smells or gets hot while idle;
• it loses most of its runtime on the same job;
• it cuts out under light load, or the charger rejects it;
• the case is cracked.

Take a bad pack to a battery recycling point; don’t put it in household trash or leave it where it can catch fire. When you buy a new pack, a platform that matches your tools saves money, and combo kits often include extra batteries.