Should we really worry about 'hoverboard' batteries catching fire?

Lithium-ion batteries have been the center of controversy following recent news of overboards catching fire. Overheated lithium-ion batteries have been fingered as culprits behind the sudden flare-ups of hoverboards in the United States, causing widespread concern over their use.

The controversy even prompted UN Aviation panel to assess whether rechargeable lithium-ion batteries should be allowed at all on passenger airplanes.

Since 2013, the International Civil Aviation Organization (ICAO) has been imposing temporary ban of these batteries in passenger airplanes.

Recently, the US Federal Aviation Administration (FAA) has been proposing the prohibition of spare lithium batteries, or those not installed in any portable device, from being carried by air. However, in October last year, the UN rejected the proposal.

Lithium-ion batteries are used to power consumer electronics, such as smartphones, tablets, laptops, electronic toothbrushes, and hoverboards. As such, thousands of these batteries are often shipped on a single plane.

The latest experiments conducted by FAA revealed that few defective or damaged batteries could suffer from thermal runaway, which occurs when there is an uncontrollable increase in temperature. This may lead to overheating batteries, which could start an explosion in a shipment that would allow halon gas in cargo compartments to escape.

Halon is a liquefied, compressed gas that chemically disrupts combustion, halting any fire from spreading in the aircraft.

Here in the Philippines, few airline companies have already banned lithium battery-powered personal transportation devices, such as hoverboards, for safety reasons.

Most-used commercially

There are various types of batteries that are used commercially, ranging from Lead-Acid, which is primarily used in vehicles; Nickel Cadmium (Ni-Cd), which was phased out and replaced by Nickel Metal Hydride (Ni-MH); and Lithium Ion (Li-ion). Among these, Li-ion batteries are the most reliable and the most convenient type of portable power.

“Lithium-ion has the highest energy density—or the amount of energy a battery can store—which is very important for applications [that] are non-stationary,” said Dr. Joey Ocon of the Department of Chemical Engineering of the University of the Philippines-Diliman. “In the first place, the technology used to produce lithium-ion is already highly mature.”

Ocon, who is one of the seven Outstanding Young Scientists for 2015 named by the National Academy of Science and Technology (NAST), specializes in electrochemical engineering and is part of the team that develops better, slimmer, and more environment-friendly batteries with higher energy densities than the conventional lithium-ions.

In the case of hoverboards, Ocon believes that the units may be lacking in thermal management system, which is necessary to regulate the heat produced by the battery during its chemical reaction.

Batteries are normally hot when charged due to the energy being pushed into the packs. As the temperature increases, the chemical reaction in the batteries accelerates as well.

The huge size of the batteries used in hoverboards contributes to the amount of heat produced during the charge and discharge cycle, Ocon explained. Since these lithium-ion batteries, which are made of a number of cells, are highly-compact, it’s a challenge to have a provision to maintain the temperature.

“The majority of [these batteries’] components inside are organic electrolytes. These are highly-flammable chemicals,” he said.

Caveat

While there is no record yet of accidents involving exploding batteries or hoverboards, the Department of Health and the Department of Trade and Industry have issued a joint advisory over the use of hoverboards.

“Currently, the FDA-DOH regulations under ISO 8124 standard for toys only allows the use of 24 volts and below for electronically-activated toys for children under 14 years old of age,” the joint statement said.

Most hoverboards are found to exhibit 36-volt or higher capacity batteries.

But what worries Ocon more is the gradual infiltration of substandard batteries and hoverboard units in the market. Cheap components of batteries are more at risk of short circuits, which can ignite explosions and may even cause fire.

It is also important to change the batteries every two to three years, said Ocon. Due to a repeated cycle of charges and discharges, the battery’s ability to hold energy degrades over time.

Consumers must also be mindful of the chargers they purchase. Some cheap chargers do not have the charging controls that limit energy getting into the battery once it is full.

“Such incidents may cause panic if we fail to understand how it works,” Ocon said. — TJD, GMA News