One of the nice things about the Odyssey batteries is that they hold a charge really well....like 95% of their charge over the course of a year. The one I had in my 170 I never touched, though the airplane flew sorta regularly in winter. But, that airplane was outside in some brutally cold weather.
After I think seven years, I started thinking it was time to change the battery, so I removed the Odyssey, and installed a new one. The one I removed was still good, and my lawn tractor needed a battery, so I installed the old Odyssey in it. Parked it over winter....no disconnect, no nothing, parked in a cold shed in NW Minnesota. Next spring, I recalled my screw up, and figured I'd have a toasted battery. Put the key in the switch, turned it, and the lawn tractor fired right up.
That battery parked in that tractor all winter in cold, and held plenty of charge.
Unless you really, really run an Odyssey battery down, don't charge it.
MTV