[Ol' Dan Tucker]

They were designed to last for the life of the aircraft, so technically, there is no design problem.

If you're talking about Lithium batteries, they have a maximum life of about 2-4 years, whether they're used or not. Depending on how they're used, this could be shorter.

They definitely won't last the life of the airplane, which is 20-30 years.

[RFEngineer]

“They definitely won’t last the life of the airplane, which is 20-30 years.”

Not if the Lithium battery catches on fire, which was the unspoken punchline.

[tpmintx]

They definitely won't last the life of the airplane, which is 20-30 years.

I think that the point here is that the 787 lifespan is going to be measured in weeks. Hence, these batteries are certainly going to last for the life of the aircraft.