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Safe charging of portable lithium batteries

Some precautions to bear in mind in order to minimise the fire risk from the use of lithium batteries

Fires caused by lithium batteries sporadically make the news, and CERN is not immune from this phenomenon. CERN has experienced several fires caused by a lithium battery in the course of being charged. The subsequent investigations revealed lessons for all of us.

Lithium-ion or lithium-polymer batteries are typically used in electric cars, e-bikes, computers and other power-operated equipment as well as smartphones or e-cigarettes. Even when they’re small these batteries are miniature power plants.

Here are some precautions to bear in mind in order to minimise the fire risk from the use of these batteries:

Things you should do:

  • Use according to the manufacturer’s instructions
    Read and follow the manufacturer’s instructions precisely!
  • Use safe batteries
    Make sure your batteries are safe: regularly check the condition (damage, deformation, leakage…) of the battery and immediately replace any damaged battery.
  • Use a suitable charger
    Use the charger supplied with the battery. It is designed to monitor the charge and avoid overcharging. If the original charger is not available, you may also use a CE certified charger approved for the particular device.
  • Charge under supervision
    Supervise the charging of your batteries, in particular for powerful ones like e-bikes batteries, for example.
  • Remove battery from device
    Where batteries are designed to be removed for charging, always remove the batteries from the device before charging.
  • Unplug
    Unplug the charger once the battery is charged.
  • Dispose safely
    When not in use leave your batteries, in particular powerful ones, in a fire-proof cupboard or bag, if possible. Batteries are hazardous waste that must be disposed of following the appropriate procedures: https://sce-dep.web.cern.ch/waste/what-goes-where#Batteries. As batteries are never fully discharged it is recommended to seal the electrical poles with tape and/or put them in fire-proof bags prior to disposal.

Things you should avoid:

  • Charge under high temperatures
    Don’t charge a battery when the ambient temperature is above 35 °C.
  • Charge close to combustible materials or hazardous substances
    Do not charge batteries close to combustible materials or hazardous substances (chemicals, explosives…). Avoid charging underground if possible.

Immediate actions you should take in case of overheating or fire

In the event your battery is overheating, swelling, melting, emitting smoke or a clacking sound evacuate the premises, close the door, warn your colleagues and call the CERN fire brigade at 74444 or +41 22 767 4444.