An Andersen Plug is the specialized socket at the end of what we call a ‘charge circuit’. It allows charge from the car battery to flow through to the caravan battery. It works exactly the same as a dual battery system that you would find under the bonnet of many 4WD’s. So whilst they are theoretically charge circuits we often call them Andersen Plug systems, as that’s become their nickname.

There are two options on a charge circuit.

  • Andersen Plug with large charge wires
  • 12-pin plug with medium charge wires

Sometimes you will get a choice of whether you prefer everything to be within one plug (12-pin is ideal) or whether a separate plug is no issue. A 12-pin plug can only accept medium thickness wires whereas an Andersen plug will accept larger wires which means we get a better result when charging the battery in the caravan.

Andersen Plug with large charge wires.

Andersen PlugThis circuit is very simple. It runs large cables (almost like battery cable size), which are often 6 B&S (around 13mm in total diameter) and run from the car battery directly to the caravan battery, via large maxi fuses and through the hardy Andersen plug. Andersen plugs usually grey in colour are the same in their plug and socket form. A caravan battery that’s getting low on charge can be charged within a few hours of driving with the larger Andersen plug cables.

12-pin Plugs.

12-pin plugA good option where just one plug is required as some caravanners find the additional Andersen plug more work. The 12-pin plug can only take a 6mm diameter wire so it will not provide the charge of an Andersen plug system. The connection pins within the 12-pin plug also aren’t as strong at carrying the electrical current as the Andersen plug, however the advantage of this system is its simplicity.


Requirements 12-Pin Plug Charge Circuit 6mm Wire on Andersen Plug 13mm Wire on Andersen Plug Switch
Some charge to the battery but need simplicity on hookup Best Option
Want to maximize charge to caravan battery Best Option
Caravan already has Andersen Plug Best Option if 6mm wire Best Option if 13mm wire
Caravan already has 12-Pin plug Best Option