One of the things I was told after I bought my airplane was to take the battery out every year and hook up a small 12 V light to it and kill the battery completely and then use a low amp (2 to no more than 6 amp) battery charger to charge the battery from 2 to 5 days. Stop charging after it reach a voltage above 13.3 V. disconnect from the charger for two to five minutes
That worked for me for many years, those battery are very small and have to start a 540 C.I. low compression flat 6 cylinder in the airplane with a 4 to 6 ft. long cable to the starter solenoid from the battery
The battery was mounted behind the baggage compartment for weight and balancing it to get the center of gravity in a safe position no matter how the aircraft was loaded: up:
I did need to do weights and balance checks when I first got the airplane to learn how to load it safely