FWIW: Per advice given here, I fully discharge an almost new 12 volt battery that’s awaiting me to finish beating a 1957 Chevy two door Belair back to life. I do it with a tail light bulb on every other month. I have several trickle chargers and connected one to the discharged battery. Several days later I went to disconnect the charger only to find it was kaput. I’m not for certain, but I believe the charger could not handle a fully discharged batter and the current limiting section went south. The battery was fully charged and in good shape after I charged it back up with a regular charger set a two amps.
These new fan dangled 12 volt batteries remain a mystery to me. My cars are 6 volt and will stay that way.
