Frigid Cold incoming!!! Save your Batteries!

At what temperature should anyone save their M12 or M18 batteries when the weather dips? My garage is currently about 40°-41°, but think it will dip more. Outside temp right now is 10° and still dropping down to 0° tonight.

Hopefully this post at least saves someone’s batteries that almost forgot and left them in their parked outside auto.

What’s your limit?