If you're looking to become a true OCDI’m looking at regularly to monitor battery level. ( borderline OCD).

A shunt-based battery monitor has a shunt that fits on the battery negative terminal, so that all the amps to and from the battery has to flow through it. It measures amps, and has a clock and microchip which keeps track of the amp-hours into and out of the battery. So you always know the state of charge accurately, even when charging or under load. The Victron monitors are quite popular - the BMV types have a separate display panel, and the SmartShunt doesn't, but uses a phone app by Bluetooth. There are other types like the NASA BM, and some cheaper ones on Ebay.