Lithium-ion tool batteries are the most expensive part of a cordless system, and how you treat them decides whether they last two years or eight. The good news: the habits that protect them are simple, and mostly come down to managing heat and charge level.
1. Keep them out of the heat
Heat is the single biggest cause of lithium battery wear. A pack left in a hot car, a sunny windowsill, or a sweltering shed degrades far faster than one kept cool. If you take one thing from this guide: don't store batteries anywhere that gets hot.
2. Store at about half charge
For long-term storage — over the winter, say — leave packs at roughly 40–60% charge rather than full or empty. A fully charged pack sitting unused ages faster, and a fully drained one can slip into a damaging deep discharge.
3. Don't drain them completely, repeatedly
Running a pack to total empty now and then is fine, but doing it every single time shortens its life. Topping up before it's bone dry is gentler. Lithium batteries have no "memory effect," so partial charges are perfectly healthy.
4. Let hot packs cool before charging
Charging a battery that's still hot from heavy use stresses the cells. Give it 15–20 minutes to come back to room temperature first. Good chargers won't begin until the pack is in a safe range — don't override that.
5. Charge at room temperature
Both very cold and very hot charging are hard on lithium cells. A roughly room-temperature garage or workshop is ideal. If a pack has been outside in freezing weather, let it warm up indoors before charging.
6. Use the right charger
Stick with the charger designed for your platform. Cheap third-party chargers may skip the temperature and balancing safeguards that protect the cells — a small saving that can cost you a battery.
7. Recycle them properly at end of life
When a pack finally wears out, never put it in household trash — lithium batteries need special handling and can be a fire risk. Take it to a certified battery recycling drop-off. See our recycling guidance for how.
Frequently asked questions
Should I store lithium tool batteries fully charged?
No. For long-term storage, keep them at around 40–60% charge. A full pack sitting unused ages faster, and a fully empty one risks a damaging deep discharge.
Does leaving a battery on the charger hurt it?
A good charger stops at full and is generally safe short-term, but leaving packs on the charger for weeks in a hot spot adds unnecessary heat stress. For long storage, take them off at about half charge.
Is it bad to fully drain a tool battery?
Doing it occasionally is fine, but repeatedly running a pack to completely dead shortens its lifespan. Lithium batteries have no memory effect, so frequent partial charges are healthy.
How should I dispose of an old tool battery?
Never in household trash. Lithium-ion batteries require special handling and can be a fire hazard. Tape the terminals and take them to a certified battery recycling drop-off.
