I've had it in the back of my head that cold is affecting a few of my devices too. And overnight, winter, is usually 40's so not very cold. BUT, I've been thinking I should get a 3D printed battery and wire it up to a USB wire so I could plug it into a 'power bank' that could be 3-6 ft away depending on the USB wire I hacked. 
All of the Aeon MultiSensor 6's came with a 6ft thin USB to microUSB cable, which would be very usable for a door / tilt sensor. I'd really like to find a 3D printed fake battery that has a micro USB tucked inside 
My tilt sensor is 'glued' to the metal garage door and thus it's thermally connected to the outside temp. Kinda makes me wonder how it works, ever.
I have one of the Multisensors outdoors, under an eve, Protected from rain, but completely exposed to wind, temp, and humidity. Yet that pair of CR123a batteries are still going strong after 6-8 months.
Must have been lucky picking the battery vendor.
