Again with the Batteries
Battery Discharge and Storage
Problem
Deeply discharging a Li-Ion battery, such as the one in a Dewalt 20V sawzall, can lead to serious damage. When discharged below its safe low voltage, copper from the anode can dissolve into the electrolyte and form dendrites upon recharging, potentially causing internal short circuits.
Solution
- Ensure the battery has an internal cutoff mechanism to prevent deep discharge.
- Store Li-Ion batteries at around half charge to avoid overcharged state and to prevent damage from large ambient temperature changes.
Technical Information
Summary
Deeply discharged Li-Ion batteries won't last long, especially under varying temperatures. Proper storage and charging conditions are crucial for battery longevity.
Key Points
- Discharging below safe low voltage can cause copper dissolution and dendrite formation.
- Dendrites can lead to internal short circuits.
- Batteries should have a supervisory circuit to disconnect cells from the charger or load when voltages are outside recommended ranges.
Charging Recommendations
Overview
Charging a Li-Ion battery under specific conditions can maximize its life and performance.
Key Points
- Optimal charging temperature range: 65°F to 75°F (18°C to 24°C).
- Avoid charging below +40°F or above +105°F to prevent serious damage.
- Warm batteries charge faster than cold ones.
- If the battery pack does not charge properly, check the receptacle, ensure it's not connected to a light switch, and move to a location with the optimal temperature range.
- Charge the battery when it fails to produce sufficient power for previous tasks.
- Keep conductive materials away from charger cavities and unplug the charger when not in use.
- Do not freeze or immerse the charger or battery in any liquid.
Storage Recommendations
Summary
Proper storage conditions are essential for maintaining Li-Ion battery health.
Key Points
- Store in a cool, dry place away from direct sunlight and extreme temperatures.
- For long-term storage, store a fully charged battery in a cool, dry place out of the charger.
- Avoid storing batteries completely depleted of charge.