It’s a cold but clear winter day. Perfect flying weather is at hand as you find the motivation to bundle up and head to the airport to knock off the rust from both you and your aircraft. Snow gets shoveled, covers come off, and you climb inside after the preflight, ready to crank the engine to life and get airborne. At least that was the plan… Unfortunately, you’ve arrived to a dead battery.
Source: aopaAircraft Maintenance: Winter battery care