Welcome back to Part 2 of our guide to hassle-free and head-ache free dual battery installation tips! Let’s continue with more tricks and techniques you should be aware of, when it comes time to install an auxiliary deep cycle battery into your vehicle.

UNDERSTANDING RELAYS

A relay is best thought of as a remote control switch. They basically use magnetism from a low-power circuit to move an armature which controls a much larger circuit. For our trucks, they’re great for minimising the length of wire used in high current circuits such as driving lights or winches, which helps keep voltage drop under control. They’re also a crucial part of any installation that connects an electrical appliance to your AGM battery for camping.

To help make them last longer, mount them in a secure location, and use marine style plugs to connect the wires to the relay’s pins which offer far better protection from the elements. Make sure water can drain out easily if they get wet, and use either diode or resistor protected relays to protect against high voltage spikes to avoid damaging any sensitive electronics.

TRUST YOUR EARTHS

A large majority of electrical gremlins can be put down to poor earths that don’t properly complete the circuit between your deep cycle battery and the rest of your vehicle, either from poor installation or from allowing the elements to obstruct the connection. For high current accessories such as driving lights, you really need to run an earth cable directly back to battery negative. However, for low current device such as a UHF radio, direct connection to the vehicle body will usually suffice. It’s a good idea to use existing earth points as you know they are already trustworthy in most cases. To avoid electrical problems down the track, give your main earth contact points a good going over with a wire brush to make sure they’re metal-to-metal, and don’t forget to clean the battery earth terminal too. If you need to make a new earth point, make sure you scrape the paint off before you make the join, then give it a few coats of paint to protect the new connection from corrosion. It’s never a bad idea to have multipleearth points in your system, particularly if you have an AGM deep cycle battery installed in the rear of your vehicle.

WIRE PROTECTION

There’s no doubt about it, auto wiring and deep cycle battery components have a hard life, especially in exposed areas like the undercarriage or in the engine bay. One of the most popular ways of protecting the wiring from abrasions and other mechanical damage it is to enclose it in split conduit. To enhance the protection the conduit offers, use electrical tape to wrap the wires in a bundle, then run the tape out and around the conduit a few times. This will help stop the wires from vibrating and moving around inside the conduit itself.

Make sure you terminate the ends of the conduit with quality electrical tape or heat shrink to block water and dust from entering the conduit and prevent the wires escaping back through the split. It’s also a good idea to wrap a cable tie around the conduit at regular intervals, which won’t loosen up over time unlike electrical tape. Run this all the way to and from your deep cycle camping battery for maximum protection.

TIDY WIRING

There’s nothing worse than messy wiring. Not only does it look downright ugly, it can make it super difficult to diagnose a problem with a dual battery system, especially when you’re knee deep in mud and can’t find one of 30 in-line fuses that are scattered all over the place. One of the easiest ways to keep your wiring neat, tidy and organised is to use a fused distribution block. This allows you to bundle and route all the wires to a central location and keep all the fuses in one easy to reach location. When choosing a distribution block, take note of the maximum amps the unit can take overall, as well as the maximum amps each individual circuit can handle to make sure it’s suitable for all of your accessories. If you’ve got the feeling there are still plenty more electrical upgrades to come, it’s wise to use a distribution block with a few extra circuits spare to cut the work out down the track.

RUBBER GROMMETS

Believe it or not, something as simple as a rubber grommet can be an absolute life saver. Auto wiring often needs to pass through metal like the firewall or floor pan of your 4WD to allow you to connect an interior mounted AGM battery for camping. The problem is this metal surface is often sharp, which means all those constant vibrations out on the tracks will inevitably chaff and wear the wires insulation away causing a short circuit. At best this situation will blow a fuse, while at worst, it can start a fire. Your best bet to avoid damage is to de-burr the hole with a file, paint any exposed metal to prevent rust and fit an appropriately sized rubber or plastic grommet to the hole to protect the wiring.

DON’T ASK FOR TROUBLE

Our gear is subject to some pretty harsh treatment, and the last thing you want is your aux camping battery not charging properly. Scotch locks are a solder free, insulation displacement wire-tap device used to join two wires together without cutting or stripping off any insulation. while they have their place, they’re generally not recommended in any electrical installation that needs to last any great length of time, especially if they’re subject to Australia’s often harsh elements. Poor mechanical strain relief is the main reason they tend to fail over time, and they don’t have any way of preventing moisture from entering the joint. In short, if you want the join to last, and don’t fancy chasing electric dramas down the track, opt for a reliable joining method right from the get go.