Driving Lights

If you plan to do any night driving in the outback then a strong reliable light source is a must. Bad weather, night driving and the possibility of stray animals all demand the need for a clear view of the road and the standard vehicle high beam is not enough. In this article we provide some buying and installation tips for considering additional driving lights for your vehicle.

Buying Tips

There are a wide variety of driving lights available ranging from the very cheap to the way over-priced. Outlined below is a list of buying tips intended to help you buy better.
  • Do not bother with cheap lights because you will find that the lens will fall out or the mounts will break on your first "off road" trip.

  • Good quality lights will cost you over $100 each. Our advice is to get a good set of twin 100 watt lights.

  • Most quality lights that work well with your 4WD will generally come as packages of single lights (you will need to buy two). You will not generally find a kit (2 lights in a box) that will suit your 4WD application. Most respected 4WD specialists will be able to provide you with a suitable quality kit, however stay away from the low-cost system available from the general parts suppliers as they are not designed for "off road" use.

  • You will have the option of purchasing different lens types (depends on the lights you choose). You can usually get a spot and wide angle lens for most light set-ups. If this is an option then you should get one of each so that you gain the benefits of longer range (spot light) and better roadside lighting (wide angle).

  • Be very wary of wiring kits included with your driving lights - they are often of "cheap" quality. Good quality wiring is more expensive but is necessary for ensuring maximum current is delivered to the bulb. Cheaper wiring often results in a loss of current reaching the units.

  • You can also purchase new high powered globes for your standard lights. This will improve the power and quality of the standard headlights. Make sure that any replacement globes fall into the ADR specifications.

  • Anti vibration fittings are essential on your 4WD. See the details below for one idea of how to make your lights secure.

  • You can purchase Driving Lights from most good 4WD accessory outlets and some other accessory parts retail stores.

Installation Tips

As with all electrical devices in your vehicle the wiring is of utmost importance. Because this is so important with driving lights, lets calculate the power required to correctly power a pair of 100W driving lights.

Power Requirement Calculation

Assume the battery delivers 12V even though a car with the engine running will deliver about 13 -13.8V (dependant on battery condition).
2 x 100W gives us a total power requirement of 200W at 12V
Remember your physics and electronics - P = VI (Power = Volts * Current) or to calculate current I = P/V
The current required to power the globes is 200/12 = 16.66Amps or 8.33Amps per globe.
Add a some losses for the cable, relays and connectors and you will easily need 20Amps

  • Lights must be wired using at least 20Amp cable or a high quality wiring kit. Have a look at any cable you buy and note how thick the cable is and whether it is multi strand or single conductor. Always use a multi strand cable in your vehicle wiring.

  • You must use a relay when wiring your driving lights. You do not want to be running a 20Amps feed through the firewall. Also you should wire the relay to come on via the use of the vehicle's high beam.

  • The relay should be rated at better than the required current i.e. greater than 20 Amps. It is not that uncommon to install a 70Amp relay. The better the relay the less current and voltage drop through it. Remember voltage drop is your worst enemy.

  • You should install a fuse on the main feed from the battery before the relay. See diagram below.
  • Keep the wiring neat and away from moving parts. You should encase your wiring in some form of corrugated split sleeve tubing (available from most accessory parts stores). 13mm and 10mm are quite commonly used. See photos below.
  • Solder any crimp connection on any high current wiring to avoid additional voltage drop.

  • Anti vibration fittings must be installed on your 4WD. As the lights you fit are generally large they tend to vibrate at the top. Constant vibration will cause the lens to become loose and fall out, also the light is not as good if it is vibrating on the bull bar. An idea it to make up some brackets using long bolts cut and welded onto some flat steel and bolted to the bar.


Make sure you slow down if driving at night, even if you can see for miles with your new lights!

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Created: June 2008
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