Galaxy Note 7 recall shows challenges of stronger batteries

Samsung's recall of 2.5 million Galaxy Note 7 phones after several dozen caught fire and exploded may stem from a subtle manufacturing error, but it highlights the challenge electronics makers face in packing ever more battery power into ever thinner phones, while rushing for faster release dates.

Announcing the recall on September 2, Samsung confirmed dozens of cases where Note 7 batteries caught fire or exploded, mostly while charging. It plans a software update that will cap battery recharging at 60 per cent capacity to help minimize risks of overheating.

But it is urging owners to keep the phones turned off until they can get them replaced, beginning September 19.

The Note 7 debuted to rave reviews in August thanks to its speed, new software features and not least the estimated nine hours it would run between charges.

But all that power comes at a price: users began reporting the phones were catching fire or exploding, in one case incinerating the SUV it had been left in.

Aviation authorities in the US, Australia and Europe have urged passengers not to use or charge Note 7s while flying and not to put them in checked baggage. On Monday, Canada issued an official recall.

Koh Dong-jin, Samsung's mobile president, said in announcing the recall on September 2 that an investigation turned up a "tiny error" in the manufacturing process for the faulty batteries in the Note 7s that was very difficult to identify. The end of the pouch-shaped battery cell had some flaws that increased the chance of stress or overheating, he explained.

That kind of manufacturing error is unimaginable for top-notch battery makers with adequate quality controls, said Park Chul Wan, a former director of the next generation battery research center at the state-owned Korea Electronics Technology Institute.

Samsung and other experts should search for factors outside the battery cells that could have led to overheating, he said.

"If Koh's argument is right, that makes Samsung SDI a third-rate company," Park said. "But it does not appear to be a simple battery problem."

Time also is a factor in marketing and making the phones. In 2015, Samsung moved up its unveiling of its new Galaxy Note model to August from September, seeking a leg up on Apple's September iPhone upgrades.

Before the issue of battery explosions emerged, supplies were not keeping pace with demand for the Note 7.