I've been doing some engine room improvements associated with electrics. Our Adverc Battery Monitor, which gave good service for many years, gave up the ghost when it got wet (engine overheating!). I decided to go down a slightly different route with the new monitor and purchased a Sterling ProCounter that monitors volts, amps and amp hours. I was also attracted by a Adverc Quick Monitor which is a voltage indicating LED that indicates approximate state of charge - "as it says on the tin". This should be useful to glance at when passing through the engine room.
Sterling Battery Monitor and Adverc Quick Check
For several years I have considered upgrading the Victron inverter/charger. Our original, that came with the boat, was a physically large (and heavy) quasi-sine wave version (circa 1995). I have now replaced it with a new Victron - a 12 volt/1200 watt/50 amp MultiPlus Compact. It is considerably smaller and lighter than its predecessor and has a better performance.
Victron MultiPlus Compact Inverter/Charger
My last improvement was to add some new plastic signs to indicate the battery isolation switches. Previously I used some laminated self-made signs. These are much smarter. It is amazing what you can get designed and made on-line for very little cost.
Engraved plastic signs