We have completed the purchase of a 2008 Beneteau 40 that has a Siemens VDO digital monitoring of the battery voltage, freshwater, and fuel. The system will only display the freshwater tank levels, regardless of whether you press the button for the battery or the fuel. The only time that we can see anything regarding battery voltage is when a low battery alarm sounds. Does any one have any experience with these gauges and where do I get additional help.