Industry Topics

General Lithium Ion Battery Safety

Safe Handling and Use of Li-Ion Batteries for Power Tools

For many years, the chemistry used in power tool batteries was commonly nickel metal hydride (Ni-MH) and nickel cadmium (Ni-Cd). During the past decade there has been an almost universal conversion to lithium-ion (Li-Ion). There were numerous reasons for the change, such as higher energy density (more energy in a smaller size), lower-toxicity materials, no memory effect, slow rate of self-discharge. The benefits of this newer Li-Ion technology have allowed higher-demand tools and applications to be battery powered, and provide significantly more work-per-charge. This extended capability, combined with the portability of battery tools, has resulted in a dramatic increase in their use.

A battery is designed to direct its energy along defined pathways in a controlled manner. When the energy finds a different, possibly even uncontrolled path, contact with caustic chemicals, burns from escaping chemicals, fire, or explosion can result – in some cases weeks after an internal fault occurs. The higher the energy density of a Li-Ion battery, the greater the potential to cause damage.

Each original equipment manufacturer (OEM) has its own proprietary control circuity for the total system, which encompasses the tool, battery, and charger. This is so the three components communicate properly. There are numerous design considerations manufacturers address in the construction of their batteries: type and quality of cells; durability of electrical connections; electronic controls (in the battery, charger, and tool); protective housing; compliance with standards and 3rd-party certification; etc.

For all these safety and compliance considerations, batteries are not cross-compatible (unless specified by the power tool manufacturer). When buying aftermarket batteries for power tools, it is important to consult with the power tool owner’s manual and purchase only the batteries recommended by the manufacturer. 

In addition to knowing these basic facts about power tools and their batteries, it is also important that users handle Li-Ion batteries properly to avoid accidents.

Following are some of the most common precautions for the safe handling and use of power tool Li-Ion batteries. Failure to follow these precautions can result in burns, fire, or explosion.

  • You must always read your manufacturer’s instruction manual (battery, charger, and tool) for complete information
  • Only use original manufacturer’s system components – tool, battery, and charger. Each manufacturer utilizes their own unique control circuity which allows the system to communicate properly. This system monitors and controls critical functions, such as cell balance, energy levels, flow of energy in/out, and temperatures.
  • Do not impact or damage a battery (e.g., do not use it as a hammer), use it solely for the defined purpose as specified by the manufacturer. Inspect your battery regularly for signs of damage, such as crushing, cuts, or punctures. Do not use a battery that has received a sharp blow, been dropped or is damaged.
  • Never modify, disassemble, or tamper with the battery. The performance of damaged or modified batteries can be unpredictable and dangerous. Do not short circuit the battery terminals. Battery pack will short circuit if a metal object makes a connection between the positive and negative contacts on the battery pack. Do not store or transport the battery in a container with loose metal objects, such as coins, keys, or nails, which may contact the terminals.
  • Be mindful of abnormal battery behavior – failure to fully charge or hold a charge, longer-than-usual charging times, noticeable drop in performance, unusual LED activity when placed on a charger (with batteries so equipped), liquid leakage from the battery, or melted plastic anywhere on the pack. These are indications of an internal problem.
  • Use and store your battery within the temperature limits stated by the manufacturer. Do not store in a closed location where sunlight may cause elevated temperatures, such as near a window inside a vehicle.
  • As a general practice, it is best to unplug battery chargers and remove battery packs when not in use. Do not store batteries on their chargers.
  • Never burn / incinerate a battery or expose to a heat source – it may explode.
  • Do not immerse the battery or allow any fluids to flow inside. Conductive liquid ingress, such as water, can cause damage resulting in fire or explosion. Store your battery in a cool, dry place, away from combustible and flammable items. Corrosive gas atmospheres must be avoided.
  • If you suspect your battery may have a problem, do not use, ship, or discard as normal trash. Always dispose of your battery pack according to federal, state, and local regulations. Contact a recycling agency in your area for recycling locations. Even discharged battery packs contain some energy. Before disposing, use electrical tape to cover the terminals to prevent the battery pack from short circuit.
  • There are also carrier requirements that need to be considered when shipping Lithium-Ion batteries (see resources below for examples).
  • Do not attempt to revive a battery that will not take a charge. Do not jumpstart, use other batteries, or use other power sources. Doing so may cause long-term battery damage that can result in burns, fire, or explosion.


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