If you wish to run 240V appliances such as a 240V TV or a laptop computer in your RV from a 12V system you will need to install an inverter. An inverter is an electrical device that converts 12V Direct Current (DC) from the batteries to 240V Alternating Current (AC). Invertors also draw their power from a 12V deep cycle battery or battery bank (several batteries wired in parallel).
As inverters produce 240V always exercise caution as it is as deadly as mains power.
When investigating inverters you will come across the terms square wave, modified square or sine wave and pure sine wave. The most popular inverters, even though they are a bit more expensive, are pure sine wave as they deliver the most constant output and run sensitive appliances such as laptop or notebook computers. The cheaper inverters are modified sine – don’t be fooled into purchasing anything but a pure sine if you wish to run switch mode power supplies such as used for laptops or electric motors.
Power inverters come in a range of models and sizes that vary in watts. If you just require power for say two lights, a radio and a small laptop computer then a 500W inverter connected to a 12V power socket may suffice but if you wish to use a larger laptop computer, DVD or TV and mobile telephone charger or a bread maker then a larger inverter would be necessary. If you want the inverter connected into fixed wiring this work must be done by a licensed electrician.
Some electrical appliances have a ‘start up surge’ or ‘peak load’ when turned on which is much higher than their continuous draw or ‘continuous load’ so the size/capacity of the inverter will need to cope with this. Another example is if you wish to use tools such as an electric drill then the size/capacity of the inverter would need to cope with the drill under load. Adequate power stored in the RV battery bank would also be needed.
Depending on the way the wiring has been done you may have to turn off the RV battery charger when using the inverter.
Owners of off-road caravans are now having the 240V wiring specifically installed in their RV to be able to isolate the battery charger and the air conditioner when the inverter is on, but still run those appliances from the generator at the same time if they wished to do so.
Caution: Any electrical work must be carried out by a licensed electrician and you should let the electrician know there is an inverter installed. The Owner’s Manual for the Xantrex 1800W inverter states in part – ‘disconnect the DC power (and AC power if applicable on hardwire versions) from the Sine Wave Inverter before attempting any maintenance or cleaning or working on any equipment and circuits connected to the Sine Wave Inverter. Turning off controls will not reduce the risk’.
These large Xantrex 1800W inverters are designed to be used with deep-cycle lead acid batteries and Xantrex recommend a minimum battery size of 200 Ah for moderate loads (less than 1000W) and greater than 400 Ah for heavy loads. The Xantrex owner’s manual also provides information concerning cables and adequate cable gauge.
Some brand names/suppliers for inverters are Xantrex Technology Inc, Victron Energy Shop, Smartpower Inverters, Vector Inverters and Sinergex Inverters.
Inverters can also be purchased from Bainbridge Technologies, Dick Smith Electronics, Jaycar Electronics, Springers Low Voltage Specialists, Rainbow Power Company Ltd, Solar Xpress, The 12V Shop as well as RV accessory outlets.
12 volt 3 wayIf you don’t want to use an inverter, then 12V appliances are available but you may find some of these expensive as well as draw too much current. Further, the caravan wiring may be inadequate for the amount of current these appliances draw.
There are generators that have an additional smaller 12V DC output for running 12V appliances direct.
12V appliances can be sourced from specialty stores, some caravan and camping outlets, Camec, Boating Camping & Fishing (BCF) stores as well as marine stores.
Essentially, you will still need some mains electrical backup, diesel fuel or LPG gas to run any hot water system or for cooking.