BU-304c: Battery Safety in Public

The interest in batteries is growing, but stored energy must be respected. Children and adults alike are often unaware of the potential safety hazards when experimenting with batteries by heating cells, crushing them or applying an electrical short. Some batteries disintegrate with such a force they can cause serious harm, such as the loss of an arm or death. The damage inflicted depends on the chemistry and lithium-based cells are the most potent. Pay special attention to lithium-metal, the most energy-dense cell that is also the most powerful when stressed beyond its limits.

Health Canada reports receiving over 100 consumer reports in one year involving batteries. Failures involved overheating and starting fires. Officials responsible for safety say: “Any type of battery could be a potentially problem.” This applies mainly to batteries containing lithium. Smoke detectors are highly recommended to alert smoldering before a fire develops.

Folks are familiar with the alkaline, but this is the pussycat of batteries. Other systems are less forgiving and this article looks at common battery systems in the hands of the consumer. We learn how to care for batteries, what to watch for when traveling and how to stay out of trouble with correct handling.

Alkaline

In spite of alkaline being forgiving, never mix batteries metallic objects. Do not store batteries in close proximity to flammable materials. There are reported incidents of batteries setting fire. Fire inspectors recommend storage containers that secure batteries so the positive and negatives terminals won’t touch.

Alkaline batteries cannot be charged, or at least they should not. This does not stop individuals from trying to get some energy back into the cell. Ordinary alkaline batteries have been recharged in households for many years. Recharging is most effective if the cell is not discharged beyond 50 percent. Depth of discharge governs the number of recharges and is limited to just a few. Battery makers do not endorse this practice for safety reasons; charging ordinary alkaline batteries may generate hydrogen gas that can lead to an explosion. (See BU-211: Alternate Battery Systems; go to Reusable Alkaline).

Button cells

The button cell, also known as a coin cell, is used in toys, watches, hearing aids and medical devices. Children like to play with button cells, putting them in their mouth and possibly swallowing them. In the United States alone, each year more than 2,800 children are treated in emergency rooms for swallowing button batteries. According to a 2015 report, injuries and deaths from swallowing batteries has increased nine-fold in the last decade. (See BU-703: Health Concerns with Batteries)

Lead acid

Do not store starter batteries where children play as the terminals of a starter battery are made of lead. Lead acid also has one of the most corrosive electrolytes of all batteries that must be safeguarded.

Lithium-ion

From 1991-2016, 138 airport and flight incidents involving lithium batteries occurred. These include 13 E-cigarettes, 7 mobile phones/tablets, 7 spare batteries and 4 laptops. E-cigarette incidents increased the most.

According to published reports, 68 percent of battery failure in transit is caused by short circuit, and poor packaging is much to blame. Do not store and transport bare batteries in a metal box; do not mix batteries with coins, house keys in your jeans. Always put cells and batteries in clear plastic bags.

Lithium Batteries

While Li-ion is rechargeable, there are non-rechargeable lithium batteries that exceed Li-ion in capacity. They contain a metallic anode and are often called lithium-metal. This increases volatility and these batteries are subject to tighter shipping regulations than the more benign lithium-ion. Primary lithium batteries come in many varieties and are mainly used for industrial uses. (See BU-106a: Choices of Primary Batteries)

Lithium iron disulfide (LiFeS2) is a replacement of the regular household alkaline with longer runtimes and better loading capabilities. Lithium batteries normally deliver 3 volts and higher, LiFeS2 is 1.5 volts, making it compatible with the AA and AAA formats. They cost slightly more than alkaline and must follow transportation rules.

Lithium thionyl chloride (LiSOCI2 or LTC) can withstand high heat and strong vibration. Thanks to the wide temperature operating range, LTC batteries are mainly used for horizontal drilling, also known as fracking that reaches head temperatures of 125°C (257°F). With a specific energy of over 500Wh/kg, they offer twice the capacity of the best Li-ion. Even though rugged and seemingly indestructible, this battery is one of the most potent if abused. Because of the potential danger, LTC is not permitted in consumer products; it also requires training for handling.

Lithium manganese dioxide (LiMnO2 or Li-M) is another common metallic lithium battery that is more benign than LTC. It comes with a lower capacity and is safe for public use. Typical uses are meter sensing, medical devices, road toll sensors and cameras.

Effect of Aging

Li-ion batteries are safe but what may not be fully understood with a growing battery population is aging. Users ask: “Will my battery die quietly or depart with a bang?” Typical usage patterns that stress a Li-ion battery are excessive loading, rapid-charging and charging below freezing. Furthermore, storing Li-ion at a voltage below 2 volts per cell leads to dendrite growth that can damage the separator and cause a mild electrical short that can progress into a full electrical short, even if kept in storage. A small water leak in a faulty hydro dam can advance to a torrent and take a structure down, so also can separator damage lead to venting with flame. The temperature rises to 500°C (932°F), at which point the cell catches fire or explodes.

If a Li-ion battery overheats, hisses, or bulges, immediately move the device with battery away from flammable materials and place it on a non-combustible surface. If at all possible, remove the battery from the device and put it outdoors to burn out.

A small Li-ion fire can be handled like any other combustible fire. For best result use a foam extinguisher, CO2, ABC dry chemical, powdered graphite, copper powder or soda (sodium carbonate). If the fire occurs in an airplane cabin, the FAA instructs flight attendants to use water or soda pop. Water-based products are most readily available and are appropriate since Li-ion contains very little lithium metal that could react with water. Water also cools the adjacent area and prevents the fire from spreading. (See BU-304a: Safety Concerns with Li-ion)

A large Li-ion fire, such as in an EV, may need to burn out as water is ineffective. When encountering a fire with a lithium-metal battery, only use a Class D fire extinguisher. Lithium-metal contains of lithium that reacts with water and makes the fire worse. Do not use the Class D fire extinguisher for regular fires.

Statistics

A recent study from George Mason University estimated over 2,000 visits to U.S. emergency rooms caused from explosion-related injuries from e-cigarette burns from 2015 to 2017. Most injured were men putting e-cigarette batteries in their jeans or shirt pockets. Some also had keys in their pocket, a dangerous mix of metal and lithium-ion batteries causing an electric short. Many experienced severe burns to their legs, arms and hands, even death. Figure 6 provides statistics.

References

[1] Source: News Calgary 2017
[2] Source: FEMA (U.S. Fire Administration)