These two units from long time supplier Jaycar Electronics are at present the cheapest way to put 240 volt with double isolation into your motorhome. We haven't actually used one as they are very new on the market and Collyn Rivers put us on to them. Jaycar have an excellent website and you can buy online. When we last checked their inbuilt search engine wasn't showing the 150 watt model. Jaycar are very SLOOOOW to answer emails but they eventually get around to it! On paper these units look OK as they have all the safety features needed to protect you and your battery.

Designed as a free-standing inverter, this 300-watt model boasts electrical isolation between battery and secondary (mains) voltage for increased safety. The build construction is outstanding, too say Jaycar Electronics the importers. The inverter is housed inside a tough aluminium case with heavy-duty heatsink and includes a cooling fan for added reliability. DC connection to the inverter is made via heavy duty binding terminals, ready to accept between 14 and 6 gauge hi-current cable. Other features include low profile mains socket, on/off switch, low battery alarm and shutoff, plus a tri-state LED indicating over temperature and overload conditions, etc. Most importantly, the overload characteristics of this inverter are excellent. This means that it will be more successful in starting up colour TVs and hand tools, for example. Easily one of the best non-industrial and cost effective inverters we have ever seen. Specifications: Output Power: 300W continuous Surge Power: 500W. Standby Current: <0.6A Input Voltage: 10.7V - 15VDC Output Wave Form: Sine Wave Efficiency: 85% Typ. Output Regulation: +/-3% Output frequency: 50Hz Cooling: Internal Fan Low battery Alarm: 10.7V Low batt shut Off: 10V Overload: Shutdown Battery Reverse: Internal Fuse Input Connectors: 6 gauge Dimensions: 107(W) x 60(H) x 280(L)mm Weight: 1.65Kg. One Year Warranty. Both these units are the cheapest wattage sine wave units currently available and Jaycar is a solid reliable supplier, however we haven't come across any motorhomer using one as yet. Country of origin is not mentioned but the specs read OK.