Sounds like the battery might not be "holding a charge", usually due to "sulfated plates". The way I tell is if it won't crank the engine (all terminals good, voltage difference too low right at posts), and I put on the charger at 10 A and it shows "full charge" after <30 min, I know it isn't storing enough energy. I have Autozone load-test it and usually shows "bad battery". I also have a Battery Brain on all cars and when it trips too often (just dome lamp and such load), I have it tested and usually "bad". I bought ~4 batteries from Autozone a few years ago on the same day for various cars & trailer and at least 2 of them failed to hold a charge within 6 months (gold top, free replacement), and I recall one or two of the replacements did similarly. Seems there are/was a spate of bad batteries in the system. Since only ~2 battery plants in the country (supplying ~40 brands), might have been due to Billy-Bob on the night shift. Great advances lately in exotic batteries, but lead-acid ones seem to be getting worse, and much more expensive.