The two lithium-ion batteries installed on board every Boeing 787 are the biggest on any aircraft’s systems. Since January 17, two incidents of batteries causing smoke have caused the temporary grounding of all 50 Dreamliners worldwide (this was still the case as this issue went to press).

But smaller lithium-ion batteries are still flying on every passenger aircraft – in the carry-on bags of most travellers. There’s hardly anyone not carrying at least one or two personal devices powered by lithium-ion battery packs – everything from smartphones, laptops and tablets to MP3 players and cameras are fitted with them.

Many passengers also put spare battery packs or other battery-powered equipment in their hold baggage. And all these “pocket-sized power stations”, as Michael Buser, a Vienna-based risk expert, calls the powerful energy storage devices, are potentially adding up to great danger.

So far a little-known problem in public, industry experts and pilots have long called for remedies. “We are concerned about the potential fire hazards posed by lithium-ion batteries,” says Richard Taylor, spokesman for the Civil Aviation Authority (CAA). “We are working with UK operators to address the problem.”

There are lithium (non-rechargeable) and lithium-ion (rechargeable) batteries, and both are capable of ignition and subsequent explosion if they overheat. And a minor disruption might be enough to cause a chain reaction, Buser says: “A small vibration can trigger a local short circuit, causing heat to develop. So lithium batteries are a big fire load, and a possible ignition source – this combination makes them potentially dangerous.”

Overheating the batteries results in a “thermal runaway”, which can cause the release of either molten burning lithium or flammable electrolyte. Once one cell goes into a thermal runaway, it produces enough heat to cause adjacent cells to follow suit. The resulting fire can flare repeatedly as each cell ruptures and releases its contents. And while such explosions could occur on the ground – say, from dropping your laptop on the street – the confines of an aircraft cabin, from which passengers cannot escape quickly or easily, make the consequences potentially more serious.

At least two recent crashes, albeit of cargo aircraft, have been attributed by investigators to burning batteries. On September 3, 2010, a UPS B747-400 freighter crashed near Dubai, while on July 28 the following year, an identical cargo aircraft belonging to Asiana Airlines came down in the waters near Jeju island in South Korea.

Following these incidents, the International Civil Aviation Organisation tightened its rules for carrying lithium-ion batteries in January, and they are now to be labelled as dangerous goods in cargo operations. But that does not tackle the hazards of battery-related incidents inside the passenger cabin and in the cargo holds of passenger aircraft.

On July 2, 2012, for example, an Emirates B777-300 on its way from Dubai to Beijing with 270 people on board experienced a fire in the hold. Luckily, the flames could be extinguished by the aircraft’s cargo fire suppression system in flight. The jet was diverted to Urumqi in China’s remote western interior, with no injuries. The airline later confirmed that the fire alert was caused by smoke from a lithium battery in a passenger bag.

Another incident occurred on April 17 last year in the cabin of a Pinnacle Airlines CRJ-200 operating on behalf of Delta Air Lines from Toronto to Minneapolis. During cruise, the lithium-ion battery of a personal air purifier on a passenger’s chest caught fire, injuring him. The burning battery was quickly extinguished by a flight attendant and the flight was diverted.

On March 19, 2007, during an American Airlines flight from Buenos Aires to Miami, a small explosion occurred in business class after a passenger accidentally dropped a camera lithium-metal battery. When hitting the metal seat frame, it exploded. Fragments hit a passenger in the head, burning her hair, and seven flight attendants were affected by smoke inhalation.

These are a few of no less than 132 cases listed by the US Federal Aviation Administration that happened between March 1991 and October 2012 on aircraft in US air space or at US airports. It acknowledges that there have probably been many more. In Europe, such statistics do not exist, though the CAA revealed new figures concerning UK-registered aircraft or incidents having occurred in the UK to Business Traveller: “There were five incidents in 2011 and 2012 where batteries in smartphones or tablets either caught fire or began to smoke,” Taylor says. “This generally occurred if the device was somehow crushed between seats.”

German authority LBA lists six battery-related incidents between 2006 and 2009 – since then, these figures are no longer published separately to other in-flight incidents. The airlines remain reluctant to admit the scope of the problem: “We have not had any incidents directly related to lithium-ion batteries”, says Adam Chaudhri, British Airways spokesman.

Sonja Ptassek, spokeswoman for Swiss admits: “We had one incident in the cabin when the spare battery pack of a mobile phone caught fire, [but was] quickly extinguished by the trained crew.” Swiss takes the problem seriously, she adds: “The energy density of the batteries is ever-increasing, so the devices powered by them become more risk-prone.”

The CAA, however, doesn’t regard the devices themselves as the main problem: “Our concern is that passengers carry spare lithium batteries in their luggage that are not installed in a device and have not been packaged in a safe container,” Taylor says.

IATA rules for carrying dangerous goods on passenger flights permit the transport of devices with installed lithium-ion batteries inside the cabin as well as in checked baggage. Spare battery packs are only allowed in carry-on bags (a maximum of two) and must be individually packaged to prevent short circuits. At the same time, they must not exceed a Watt-hour rating of 100Wh or a lithium content of 2g. More powerful batteries of up to 160Wh can also only be carried with the approval of the airline – which is probably not often adhered to.

Totally forbidding them on board, the experts agree, is not an option in this age of constant communication. And the need for batteries to feed this dependency is only fuelling the fire.