Camper Maintenance – Trailer Plugs & Battery Protection

Trailer plug maintenance is key to happy camping adventures, keeping your rig roadworthy and feeding current to your batteries. In this issue, we’ll look at maintaining trailer electrical plugs, the Anderson plug, and battery protection.

Trailer Electrical Plugs

The trailer plug controls all your tail lights and feeds power to your electric brakes. Keep a trailer plug diagram like that below on your SmartPhone, to help with troubleshooting when you’re out of range.

7 pin flat plug and socket
Photo credit: Narva

When removing a 7 pin flat plug, avoid any sideways wiggling, as this will squash the connecting pins together and stop your lights working. This is common on the end pins, being the left (yellow) and right (green) indicators, so if these stop working, check the trailer plug.

Photo credit: Supex, 7 pin plug, maintain the gap in the end pins

Make sure the pins on the 7 pin flat plug have a small gap between them like above. Also check the wires have a solid connection to the plug terminals – you’ll need to remove the plastic housing to check this. Check the trailer with another vehicle to confirm if its an issue with the car or trailer. If your trailer works with another car, it points to an issue with the plug on the back of your vehicle. You can confirm this by putting a multi meter on the socket pins. Put the black lead on the earth (white wire) and the red on the relevant pin (left, right, tail, or brakes), whatever isn’t working. You should see 12V on the meter. Refer to the plug diagram to determine the correct pins. A regular squirt of WD40 or similar will help ease the effort of connecting the trailer plug to the vehicle without too much wiggling.

Anderson Plug

The Anderson plug provides a high current charge to your trailer’s battery system using the vehicle alternator. The wiring is much thicker and better suited to long cable lengths, reducing voltage drop along its length. For vehicles without a battery management system, the Anderson plug will only provide some charge while driving, generally about 75%.

Campers with a battery management system can be fully charged when driving through the Anderson plug. The system reduces the incoming charge as it fills up, helping the battery fully absorb the charge. A fixed solar panel can offset some of these losses by also feeding in charge as you travel.

Keep your Anderson plug in top condition to help the process. An Anderson plug cover is a good way to keep moisture off the terminals when not in use. Check them regularly for any signs of corrosion or rust. Light emery paper can remove any contaminants and a light spray of WD40 reduces build-up.

Photo Credit: Battery Link, Anderson Plug Cover

Low Voltage Alarm

Ideally, you should keep your camper plugged into a 240V socket when not in use. You can do this using an Ampfibian 15A adapter which is available from our store. The adapter enables you to connect your camper 15A socket to a standard 10A household 240V inlet using a 15A power lead. This keeps your camper batteries at 100% and provides protection from electric shocks, thanks to its residual current device (RCD), which can be caused by faulty wiring or appliances connected to your camper.

Another way to help protect your batteries is to set a low voltage alarm to warn when batteries need to be charged. It’s easy for batteries to go flat. Either you forget to plug your trailer in after a trip or someone removes the power lead to use the 240V socket and forgets to pug it back in. Or maybe when camping, you’ve endured a few days of overcast conditions with limited solar charge and the batteries have run down. The alarm can also warn of a failure in the charging systems, such as the Anderson plug shorting out if left unconnected, to drag on the road.

In the Redarc Battery Management System (where fitted), simply press and hold the up and down arrows on the display consecutively for a few seconds, then scroll through to Advanced Settings, select and scroll through to “Low Voltage Alarm”. Set the voltage to 12V or 12.2V, not the default 10.5V, which is dead flat. 12.2V is around 60% charge. Any lower than this and you run the risk of damaging the batteries and reducing their life.

Redarc Manager 30 Low Voltage alarm setting
Photo Credit: Redarc, Low Voltage Alarm Setting

If this doesn’t make sense, ask us at your next service or drop into the store.