Battery heater and charging station. Batteries have a hard time charging when it's super cold out. A couple chargers and a 40 watt bulb in an old cooler should do the trick! :
Topdon USA Tornado4000 Battery Charger
Schumacher 1.5A 6V/12V Fully Automatic Battery Charger and Maintainer | Cabela's
UPBRIGHT Adapter For Breg Polar Care Cube Cold Pain Relief Ice Therapy System Model 10709 Power Supply Cord Cable Battery Charger - Walmart.com
Topdon Battery Charger 12/24v Car Auto Power Repair For Car/moto/tractor/suv/boat/truck/atv/mower Lead Acid Li Battery T4000 - Car Battery Tester & Charger Tools - AliExpress
Dewalt DCB095 8-Volt Lithium-Ion Power Tool Battery Charger - Walmart.com
Topdon Battery Charger 12/24v Car Auto Power Repair For Car/moto/tractor/suv/boat/truck/atv/mower Lead Acid Li Battery T4000 - Car Battery Tester & Charger Tools - AliExpress