What is a 'Hot Wire'?


Caravan Hot Wire Installation Has Three Purposes.
1/ Supply  power to the auxiliary battery in the caravan or trailer

2/ Supply power to the caravan fridge

3/ Supply caravan lighting power



Auxiliary caravan or trailer power (ACTP)
ACTP can be achieved through several different methods, the main aim is supply the vans auxiliary battery with optimum battery charge and supply power to the caravan fridge whilst driving or supply lighting for a limited time whilst stationary.
a/  Wire direct to the tow vehicles electrical systems. Not recommended, without correct battery
b/ Battery isolation
    Please refer to battery isolation on previous page for further information.

Typical Battery Connection

Caravan fridge power [ CFP]
Most caravan fridges are designed to operate on LPG or mains power 240 volt supply when stationary, the purpose of the12 volt hot wire is to “maintain only” the fridges temperature. Approximately two days before departing, turn on your RV fridge to mains power.
the caravan fridge is maintained only by the hot wire whist driving. The fridge is isolated from the house battery, in fact if the house battery was connected to the fridge circuit, battery power would soon be depleted.
The house batteries purpose is mainly lighting ( see LED lighting ) and usually used without inference to the two vehicle.

Caravanning lighting power ( CLP)
In some earlier caravans and trailers 3 way systems did not exist , 3 way systems are, LPG, 240 & 12 volt as a power source.

CLP was via the tow vehicles electrics and the hot wire was used for this purpose and as result depleted the tow vehicles battery power, many advances have delivered, products,such as LED Lighting, Inverters, Solar energy, Battery isolation,  to over come battery depletion.
For further information see battery support

How do I connect a hot wire ?
The hot wire is connected via the trailer connector. on a 7 pin connector, pin number 2 is battery power and pin 3 is earth. The 12 pin connectors allow for more current carrying capacity, pin 9 for battery supply and pin 10 for earth return.
12 pin connectors are used mainly when the axillary battery requires charging from the tow vehicle, another alternative to a 12 pin connector is the Anderson plug. The Anderson plug, usually 50amp, negates the need for a 12 pin connector, pins 9 & 10 are routed via the Anderson plug.  
When using 12 pin or Anderson 50 amp connectors, 8 B&S cable must be installed from the power source to the power recipient

typical main battery to caravan connection


Trailer plugs&wiring connections


For further information regarding your Central Coast caravan or recreational vehicle wiring needs, please complete the enquiry form and remember Woy Woy Auto Electrics supply complete technical support with every purchase