2 years later...

[dontpanicbobby]

I'm getting battery problems. A factory-reset is in my future.

 

[lvt]

Factory reset won't cure your battery problem, it would only make your phone run a bit smoother for a while.

 

[dontpanicbobby]

I think it's a problem with a cancelled Google project; Adoptable Storage

I'll take out the MicroSD card that gets wiped and start over without it.

 

[lvt]

Not surprised.

The adoptable storage has been ignored by major brands like LG, Samsung... They explicitly disabled adoptable storage in their ROM.

 

[lvt]

But returning to external storage won't help with battery either. You phone is 2 years old, the battery need to be replaced.