Pre-Trip 12V Electrical Checklist for Touring Vehicles
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A pre-trip 12V electrical checklist catches the small faults that cause big problems on tour: a loose lug, a corroded terminal, a missing spare fuse or an auxiliary battery that isn't charging. Work through these steps in the driveway before you leave, not on a remote track.
1 Check the Batteries and Charging
Inspect the start and auxiliary batteries for corrosion, loose terminals and damaged cable ends.
Read the battery voltage and compare it with your battery maker's figures. Lead-acid, AGM and lithium batteries all differ.
Start the engine and confirm the auxiliary battery is charging, whether that's through a DC-DC charger, isolator or solar controller. Our dual battery systems guide covers the basics.
Consider a battery monitor. The Victron SmartShunt connects to the VictronConnect app by Bluetooth and shows state of charge on your phone. It comes in 500A, 1000A and 2000A versions, so choose one to suit your system.
2 Inspect Cables, Lugs and Plugs
Look for heat discolouration, melted insulation, chafing and cracked lugs, especially where cables pass through bulkheads.
Tug-test each connection. A loose terminal creates resistance and heat.
Check Anderson-style plugs for heat marks, bent pins and housings that latch firmly. Our Anderson style connector guide explains what to look for.
Confirm main cables are protected by a fuse or breaker close to the power source.
3 Check Fuses, Breakers and Spares
Open every fuse box and look for corroded or loose fuses.
Never fit a bigger fuse to stop one blowing. A fuse protects the cable, so a blown fuse is a sign to find the fault.
Pack spares. The ANS Zeeman Fuse Grab Kit comes in a VES plastic grab case with five each of 30A, 40A, 50A, 60A, 70A, 80A, 100A, 125A, 150A and 175A MIDI fuses, rated DC32V or less.
That kit only covers MIDI fuses, so also carry spares of any blade fuse types you use. Not sure what rating you need? See our guide to MIDI fuse sizing for a 12V system.
4 Test Every Accessory Under Load
Run the fridge, lights, compressor, USB outlets, UHF radio and inverter together, the way you'd use them on tour.
Feel cables, plugs and sockets for unusual warmth.
Watch for dimming lights, a fridge that cuts out or chargers that drop out. These can point to voltage drop on a long or undersized cable run.
If you've added accessories to factory circuits, re-check each tap and fuse. Our guide to add-a-circuit fuse taps explains how they work.
5 Check Lights and Trailer Connections
Test headlights, indicators, brake lights and reverse lights on the vehicle and the trailer or caravan.
Inspect the trailer plug and socket for corrosion and bent pins.
Test beacons, work lights and driving lights if you have them fitted.
6 Pack a Basic 12V Repair Kit
Know When to Call an Auto Electrician
Follow your equipment and vehicle manufacturer's instructions. If you find melted plugs, repeat fuse failures or anything you don't understand, have a qualified auto electrician check it before you leave.
Ready to Hit the Road?
Work through this pre-trip 12V electrical checklist before every big trip and you'll catch most faults while help is still close.
SHOP FUSE GRAB KITS