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Stage Three, Turning on.

Turning on the 12v Electric system

The 12v electric system runs the 12v strip/spot lights, water pumps for the main water system and the cassette toilet. 12v’s are also needed to run appliances such as the gas side of the water heater, fan master heating system and some fridge/cooker ignition systems.

Connection: A 12v battery MUST be fitted to the caravan to supply the 12v electric system. With a battery in good condition all the above items will work correctly.

 Most caravans will have a main 12v switch to turn the system on situated above or near the main door. Modern caravans will have a display panel of some sort and older vans will have a switch. 

If you have a Swift caravan post 2010 there is also a system shut down button situated in the top left hand corner of the main control box either in a cupboard or under a front bunk that has to be depressed to allow 12v to go to the control panel.

How Is My Battery Charged?

240v from the mains goes through the transformer and is converted to 12v’s, which is wired to the battery and keeps it charged up.

Do I Still Need A Battery? 

The answer is YES. The battery “levels” the voltage at 12v, the transformer on its own can give up to 17v. Some of the electrics in the caravan are volt sensitive and could be damaged if a battery is not in place. 

How To Check Your Battery

This is important to check the battery for the above reasons and is simple to do. If you use the mains all the time and you have a transformer you may not know if the battery is working independently.

Disconnect the mains lead, then the strip lights and water pump should continue to work...

If they don’t first check the main battery fuse which is situated somewhere near the battery, if that is ok the battery needs to be checked.

If you have lost your 12v system, it could mean your transformer has stopped working and the battery has gone flat due to normal use without charging.

Looking after the Battery

 If the caravan is going to be stored for a length of time exceeding 8 weeks then it is advisable to remove the battery and charge it every month and again prior to using the caravan. This is more relevant in the winter months as the cold will have an adverse effect on the life span of the battery.

The 240v System

 With orange lead plugged into the site and plugged into the caravan and the trip switch in the up position the 240v system in the caravan will be live. The single blue switch on the right is the RCD, (residual current device), sometimes called a trip switch.The two other switches are MCB's (miniature circuit breaker). These are responsible for the circuits in the caravan. Typically, one will be 16 or 10 Amp and one will be 6 Amp. The 10/16 amp circuit will be responsible for the heaver equipment in the caravan such as the space heater, refrigerator and the socket near the kitchen area. 

The smaller breaker will service the transformer and the rest of the sockets. There is a button which will test the operation of the RCD. This should be tested periodically to ensure the caravan is protected from a fault. If 240v is lost, this will be the first place to look. If the RCD is in the up position and stays there when the test button is pressed, then there is no 240v entering the caravan, the fault may be with the box on the site. 


 The charger will charger the battery while the caravan is plugged into the 240v system. There will be a switch to operate the charger. On Swift caravans from 2010 there will be a green button on the main ECU (pictured above). This needs to be in the pressed position and will  illuminate when there is power.

On older models there will be a black switch situated below the main RCD unit, and on other makes of caravans a switch will be located somewhere near the charger. 

Power usage:

Care has to be taken to ensure the system is not overloaded due to the limited supply of amps. As a guide 2 KW, (average house hold kettle, ultra heat on full) is 8.3 amps (2000 w divided by 240v = 8.3 amps). Some caravan sites are still using 10 amp RCD's in the site box. This means that when the rest of the 240v system is taken into account, such as the refrigerator, transformer and the sockets an overload is quite frequent. Most sites are now converting to 16 amps as the modern caravan requires more energy to operate its systems. However, care has to be taken to insure that the Truma ultra heat is not on full when a kettle is used. The sudden draw on the system may trip the site box. As the site box is furthest away from the draw, it is most likely to be the box that trips, not the caravan RCD, (not 100% sure why this is, I'm not an electrician!). Any appliance over 2 KW is not recommended. Low wattage kettles are quite useful but may take a long time to boil. TV's and microwaves are low wattage, so are not a problem, that 5 bar electric awning heater may just be a bit to heavy!. The 240v system will also charge the battery when on site, most of the lights will run off 12v's from the battery. Test the battery is working properly by isolating the 240v (press the blue button) and insure the 12v lights still operate.

The water System

There are three different types of water system, an onboard pump, an exterior pump and in some cases both with an onboard water tank.

In the majority of cases, newer caravans have an onboard water pump with a pick up tube on the outside of the caravan that goes into the Aquaroll. 


 On the caravans control panel will be a pump switch, turn this on to give the water system 12v. Most pump systems have a pressure switch that operates once the tap is opened, open the tap and after a few seconds you will here the pump start and water will flow from the tap.

 Then close the tap and the pump will run on for 7 to 10 seconds then slow down and stop. The pump switch can be left on while you are in the caravan but I would recommend turning it off if you go out for the day incase a pipe blows off and floods the caravan.

 Also due to the changing temperature at night sometimes the pump will run for a few seconds and become annoying, so I recommend turning the pump switch off at night too.   

The Gas System.

 For Propane there is a knob situated on top of the gas bottle which needs to be twisted in the anticlockwise direction to open and clockwise to close. 

For Butane there will be a lever situated on the connection that clips onto the top of the bottle that twists through 90 degrees to open.

For both types of gas we recommend that the bottles are fully disconnected while traveling incase the emergency services need to remove the gas bottles in the event of an accident.   


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