Mastervolt 70405070 BattMan Pro

Battery monitor, 12/24 V DC with large, splash proof display (IP65) and power bar. Displays remaining time and stores special battery status events.
An affordable battery monitor that does exactly that: providing critical information about the status of your battery bank under all circumstances.
Moreover it will warn you when your battery bank is empty. Also displays the remaining time until your battery needs to be charged and stores special battery status events.