This is an article about Embedded Battery Safety on iOS and macOS devices.
Safety Tools for when handling batteries:
- Fireproof Safety Cabinet: Use to store hot batteries while they cool.
- Nitrile Gloves: Use to handle leaking or swelling batteries.
- A ziplock or other resealable bag: Use to store batteries that leaked.
- Safety Glasses: Wear when responding to and cleaning after a thermal event.
- Heat-Resistant Gloves: Use to handle hot batteries.
- Sand in a pourable container: Use to smother batteries during specific battery events.
If the temperature rises above 60º Celsius or. 140º Fahrenheit (the safe operating temperature) the situation may be hazardous.
Responding to a Hot Battery
- Clear the workbench of materials and debris.
- In the case of an external short circuit, unplug the device’s power adapter. The battery and device should start to cool immediately.
- Put on heat-resistant gloves and safety glasses.
- Wearing heat-resistant gloves, pick up the battery or case assembly with battery. Place the part in the fireproof safety cabinet for at least 2 hours. If you can’t remove the battery easily, place the entire device in the yellow fireproof safety cabinet
If the battery doesn’t cool significantly after 2 hours, it has an increased likelihood of a thermal event. Refer to the “Scenario: A Thermal Event” page in this chapter for additional guidance.
Actively swelling or damaged batteries are likelier to release, or “vent,” gases than intact, undamaged batteries. The gases may emit an organic odor (similar to antifreeze), and they may irritate mucous membranes and the respiratory system. A venting battery may emit an expelling noise.
Responding to a Venting Battery
- Don’t attempt to handle a venting battery or a device containing one.
- You may notice a battery is venting gases or emitting unusual odors, but it’s not experiencing a thermal runaway. If so, leave the battery on the workbench and evacuate the room for 15 minutes.
- When reentering the room, note any unusual odors. If odors are strong or irritating, leave the room for an additional 15 minutes.
- After odors in the room have diminished, put on nitrile or latex gloves and safety glasses.
- Prepare a disposal bag. This can be an ESD bag or a resealable plastic bag, such as a ziplock bag.
- Clear the workbench of materials and debris.
- If the power adapter is still connected, unplug it.
- Place the battery into the disposal bag and seal the bag.
- Put the bag containing the battery into the yellow fireproof safety cabinet.
- Notify your management of all battery events.
Don’t attempt to handle a venting battery.
Embedded lithium-ion and polymer battery cells contain no more than a few drops of liquid. If you notice excess liquid around an embedded battery, the liquid likely came from an external source. Follow the procedures below, regardless of the liquid’s potential source.
Responding to a Leakage Event
- Immediately eliminate any ignition source and debris near a leaking battery or device.
- Clear the workbench of materials and debris.
- Prepare a resealable, plastic disposal bag, such as a ziplock bag. Don’t use an ESD storage bag.
- Put on nitrile (or equivalent) gloves and safety glasses.
- Pick up the battery.
- Place the battery into the resealable plastic disposal bag and seal the bag. Place the sealed bag in the yellow fireproof safety cabinet temporarily.
- Wipe the affected area with water. Then use a cleaning solution for ESD mats on the area.
- Notify your management of all battery events.
Sometimes, a battery may smoke, emit sparks or soot, or make hissing or popping sounds. In these cases, the battery is most likely undergoing a thermal runaway. The most effective way to stop the reaction and prevent further smoke is by smothering the battery immediately. Do so by quickly dumping plenty of clean, dry sand on the battery, all at once. Don’t try to use water or an ABC/CO2 fire extinguisher on a battery that’s experiencing a thermal runaway. These methods won’t stop the reaction effectively, and they will make a bigger mess to clean afterward.
In the unlikely event that a battery experiences a thermal event, your primary concern should be your safety and the safety of those around you.
Responding to a Thermal Event
- Immediately upon noticing a battery thermal event, pour all the sand over the battery at once. Cover the battery completely to smother the reaction and limit smoke. Timing is critical; the faster you pour all the sand, the faster the thermal runaway stops.
- If you can’t dump the sand right away and the thermal runaway continues unabated, understand that the reaction is self-limiting. The thermal event should extinguish itself in about 30 seconds. The battery may continue to emit smoke for another minute or two after the event stops.
- Leave the room for 30 minutes if you’re uncomfortable. Meanwhile, the cell should rest during that time.
- After the reaction is smothered and the battery has cooled (about 30 minutes), put on heat-resistant gloves and safety glasses.
- Remove the battery and any battery debris from the sand. Place these into the yellow fireproof safety cabinet for a minimum of two hours.
- If employees are injured or feel ill, notify management.
- Sweep up the sand. Pour it back into the dispenser for reuse. Refill the sand supply to replace any lost material.
- Wipe the affected area with water. Then use a cleaning solution for ESD mats on the area.
- Dispose of the damaged battery or device, including debris removed from the sand, according to your usual waste or recycling protocols. Don’t ship batteries or devices that have experienced a thermal runaway to Apple as Known Bad Boards (KBBs).
- Order more sand from your regional supply vendor.
- Notify your management of all battery events.
A battery with a charge lower than 25 percent can’t produce a thermal event.