Cold battery warning, but it's not cold out.

[Spoink]

Hi!

This morning's flight got cancelled. The propellers wouldn't fire up and my app reported a cold battery. It was cold by California standards (49 degrees) but that's not really cold.

Swapped out the battery. Same issue. Any idea what caused this? It's been maybe a week since last charge on both batteries. Was that it?

 

[Trackman1]

What temp. does it show in battery screen?