April 9, 2013

Dealing with exploding batteries

A SMALL GROUP OF US were sitting in the Bent Bollard Bar and Grill the other morning, savoring a quiet pint before breakfast, when Old Wotsisname with the concrete boat walked in. He had a few things tucked under his arm, including what looked like an old-fashioned cookie tin and a length of aluminum drain pipe.

“What’s all that?” I asked.

You can never get a quick, concise answer from OW, but the guts of it was that he had been reading about lithium-ion batteries, and how they’re susceptible to catching fire and exploding. His handheld VHF radio and cell phone and GPS and some other electronic gadgets are all powered by lithium-ion, so he planned to build a safe place to keep them on his boat.

“I’m using the Boeing approach,” he said. “They’re fixing the battery problem on the 787 Dreamliners by enclosing them in a steel box that is vented to the outside through a titanium pipe. That way, if the battery catches fire, there will be no smoke in the passenger compartment. The passengers won’t even know there’s been a fire.”

“What makes the batteries overheat?” I asked.

“Boeing doesn’t know yet,” said OW, who’d obviously been doing his homework, “but their priority is to get all those grounded Dreamliners back in the air again.”

“Even if the batteries catch fire again?” I said.

“Even then.”

“So, are you going to keep your explodable VHF radios and all that stuff in the cookie tin?”

“Yep, and I’m going to knock a hole in the side of the hull to vent the fumes through this aluminum tube,” said OW. “If it’s good enough for Boeing, it’s good enough for me.”

“Why don’t they just use the old-style, non-exploding batteries that everybody else uses?” I asked.

“Weight,” said OW. “It’s all about weight. The whole premise behind the 787 is that it’s lighter and 20 percent cheaper to fly because it uses less fuel. That was the promise that prompted so many orders. But they’re already running heavier than they thought because they had to put in a heftier, heavier frame where the wings join the fuselage.  The designed version didn’t stand up to the testing.  The wings could have fallen off.  Meanwhile, the lithium-ion batteries are lighter.”

“How dangerous is this for sailboats with radios and things with lithium-ion?” I asked.

“Judge for yourself,” said OW. “In March 2007, Lenovo recalled approximately 205,000 batteries at risk of explosion.  In August of that year, Nokia recalled more than 46 million batteries at risk of overheating and explosion. A year or so before that, Dell recalled about 22,000 laptop batteries from the U.S. market; and, also in 2006, 10 million batteries were recalled by Dell, Sony, Apple, Panasonic, Toshiba, Hitachi, and other manufacturers.”

“Sounds like lithium-ion batteries haven’t exactly been perfected yet.”

“The U.S. Postal Service has restrictions about mailing them,” said OW. “And the airlines themselves won’t let you take spare lithium batteries in your checked luggage in case they catch fire. Isn’t that the supreme irony? It’s okay if their batteries in the Dreamliner catch fire, but not if yours in the baggage hold catch fire.”

“Just as a matter of interest,” I said, “what are the Dreamliner’s batteries used for? I mean, it’s all very well if the fire is contained in a steel box, but what happens when the batteries stop working?  What are they powering?”

“Oh, just the rudder and ailerons and landing gear and stuff like that,” said OW.  “I guess everybody who flies in Dreamliners will just have to get used to some bumpy landings in future.”  He patted his cookie tin and smiled. “But I’ll be okay.”

Today’s Thought
Exit according to the rule, first leg and then head. Remove high heels and synthetic stockings before evacuation: Open the door, take out the recovery line and throw it away.
— Rumanian National Airlines emergency instructions, quoted in The Times, London, 27 Sep 84

Adolescence is a period of rapid change. Between the ages of 12 and 17, for instance, a parent can age as much as 20 years.

(Drop by every Monday, Wednesday, Friday for a new Mainly about Boats column.)


Anonymous said...

Most modern aircraft have highly redundant electrical systems with at least 2 additional sources of power should the batteries fail. A failure that causes a loss of control in these airplanes is unlikely.

I'd be more concerned about the fact we know very little about stress fatigue in composite aircraft. We've been using aluminum to build airplanes for decades and have a lot of knowledge about how they age. AFAIK we know far less about the composite designs.

John Vigor said...

Yes, I've been wondering about that, too. Aluminum is ductile but carbon fiber isn't. But we didn't know much about aluminum in the early days, either. You may recall that the Comet's aluminum wings eventually succumbed to metal fatigue and fell off.

--John V.