System on Sailing boat: 390ah of Trojan wet cell 12v batteries plus Trojan 139ah starter battery. Solara solar panel with Victron MMPT controller. Yanmar 29hp Diesel engine with a Prestolite 90ah alternator and smart controller(Adverc) programmed to Trojan battery acceptance rates. Shore power 30ah Sterling charger. BMV712 smart battery monitor with Bluetooth connection to my Iphone. The batteries, solar panel, Victron kit, alternator and smart regulator all installEE in last 9 months.
After docking and shutting off the engine the SOC slowly drops to 83% over a few days despite solar and shore power supply. However, as soon as I start the engine the SOC jumps to 100%. The app shows that the system has synchronized on 10 occasions in the last 5 months.
What should I do to get an accurate SOC without having the start the engine?
