Not sure if this article is correct. I always thought the 787 used a generator connected to the APU to start the main engines. Wouldn't the normal start up procedure be fire up APU> connect generator to APU> start main engines using current from APU Generator. You aren't starting a big ass turbine using the battery packs buried under the passenger seats.
Article is full of misinformation and not facts.
The problem with covering engineering issues in planes is that journalists have no idea what the hell they're writing about.