Originally Posted by unctuous
Any aviation journalist who googles that will have a wealth of information on the first large aircraft downing due to Lithium Ion battery fires - so many decades ago now. Boeing stopped offering the "cargo in aft section of pax compartment" 747 Combi after that event. The Helderberg event coincided with the bulk carriage of Li Ion watch batteries that happened inreasingly - just as digital watches and pocket calculators were becoming the norm. That bulk carriage of Li ion batts in air-freight is now banned by IATA and the FAA. Not sure why a bunch of aircraft-powering Li Ion accumulators with an even higher power density is (perversely) OK, yet a properly packed container of segregated tiny watch/calculator/phone batteries is not.
Because things have progressed in the last "many decades"?
Boeing and the OEMs will have done their work and believe that they have properly tested this newer technology and that it is safe for aviation specific applications. That's progress. The watch batteries will not have had any such testing done, why would you spend a bucketload of cash for such an incidental part of a spec when you can just use sea freight?
Lithium ion batteries in aircraft will almost certainly become the norm, but the issues need sorting out first. As a new aircraft the 787 doesn't have the luxury of using tried and tested technology, if you did that you'd effectively get a 777, and as good an aircraft as that is the 787 is far better once the bugs are ironed out.