Technology Research 34730 Surge Guard, 30 Amp Protects RV from faulty park power 9100 Series Inteli-Power converters provide safe, reliable, filtered DC power to all 120-volt lighting and appliance circuits The built-in Total Charge Management System (TCMS) allows for easy addition of the optional Charge Wizard, a microprocessor-controller that constantly monitors the RV battery status and automatically selects one of four charging modes Boost Mode - (14.4) to quickly bring the battery to 90 percent of full charge. Normal Mode - (13.6) safely completes the charge Storage Mode - (13.2), automatically activates after 30 hours of non-use or Desulfation Mode - (14.4), for 15 minutes every 21 hours to prevent battery stratification and sulfation