My hybrid has never been without power. I keep it plugged in on a 20A circuit 365 days a year. I was told yesterday by a motorhome owner that it was not good to do it, although he did not give me any ...
Checking the batteries for electrolyte level and cleaning corroded connections should be part of the monthly (or quarterly, your choice) maintenance anyway. Use ONLY distilled water to top off the level, and make sure you know what the correct level is. NEVER add battery acid to a battery!