You are here

Sunlight in a can

HID lights bring daylight conditions to night, but at a cost

If you're not familiar with the term high-intensity discharge (HID), as in HID lights, you are likely familiar with their look on the road. You've been at the receiving end of HID lights when approaching cars put out a steely white shine. Until recently, such lights were only available on luxury cars. Now they are available on many high- horsepower tractors and combines. The technology isn't cheap. But do HID lights ever stand out in a field at night.

That's due to the fact that HID lights provide near daylight conditions by throwing out illumination measuring between 4,000¡ to 4,500¡ Kelvin (a light temperature scale). Daylight measures 5,000¡K to 5,500¡K.

Halogen lights, on the other hand, turn out around 2,800¡K, and incandescent bulbs shine a mere 1,200¡K.

HID lights are also highly efficient; they run on roughly half the wattage of a comparable halogen unit. For example, a 50-watt halogen generates 25 lumens per 1 watt of power. This compares to 100 lumens per watt for a 50-watt HID bulb.

Being closer to sunlight, HID lighting provides greater ground definition, says Steve Walz of J.W. Speaker Corporation, a machinery manufacturer light supplier. "This allows an operator to better discern objects at a greater distance," he says.

The technology comes at a cost. HID lighting packages (when available) tack $400 to $500 per light on to the cost of a combine or tractor. Individual HID lights bought as aftermarket products can run from $300 to $400 compared to $20 to $30 for a halogen unit.

This cost difference is accounted for by the fact that HID technology uses a starter/ballast inside the light housing. It initiates an arc between two electrodes enclosed in a tube filled with xenon gas. Starting voltage of 35,000 to 40,000 volts is needed to initiate this intense arc. Immediately after that arc is established, voltage drops to 35 to 40 volts for operation. This explains why HID draws far less power than halogen lights, and they burn much cooler.

Although this doesn't cover their additional cost, there is no filament to replace in HID lights. Their design often allows a lifetime use of 3,000 hours or greater. That means an HID light often lasts the life of the machinery it is mounted on.

These advantages help offset the additional cost of HID lighting. But much of the justification comes from how often you operate at night. "That justification is certainly more easy to make if you're working a great deal at night and need the light to run larger machinery," Walz says.

Download a PDF file of the Machinery Digest section from the Mid-February issue of Successful Farming

HID lights bring daylight conditions to night, but at a cost

Read more about