When I was about 12 I bought a kit and constructed a “Carbon-Zinc” Dry Cell battery. It was crude, but it worked for a short while. The zinc casing eventually leaked and made a huge mess. My next battery was a 12V 4AH rechargeable wet cell Nickel Cadmium battery that came from Allied Radio. It was the center of a lot of projects for maybe the next 5 years. (I can’t imagine how a 12Yr old managed to bring a very hazardous battery full of acid across the country from Illinois to Nevada in the late 60’s.) My exploration of batteries took a break until 1984 when I bought my house. I knew from my job that leaving a battery on a charger 24/7 (Think Generator starter battery.) appeared to shorten the life of these batteries. I also knew that running them completely empty could ruin them as well. My next purchase was four 100AH AGM batteries (5KWH) for a 48V 5KW UPS that I bought used. I checked the UPS batteries after a couple of years and found that two of them blew the sides off of couple cells. (You could see the plates right down to the bottom of the battery.) These batteries were held off the floor in close proximity to each other such that they could have caused a cascading failure of 5KWH of heat. (Fire?) I took that UPS out of service and purchased a smaller 24V 2.5KW Trip Lite Powerverter to replace it. I paralleled, fused and physically separated the two 100AH battery banks and put them inside a 200LB cement block cocoon to prevent a cascading failure. They are still in service today.