Adequate lighting is something every technician needs when working on a vehicle. Though some parts in today’s cramped engine compartments can only be changed by feel, most of the time it helps to see what you are doing. So a trouble light is an indispensable tool.

The traditional drop cord style trouble light that uses an ordinary screw-in incandescent light bulb is an inexpensive and practical means of providing supplemental light when working under the hood, under the dash or underneath a vehicle. A basic metal or plastic trouble light typically sells for less than $15, and usually comes with a 12’ to 25’ cord. The better models may have a 110-volt socket in the handle for plugging in other tools, and/or a swivel hook or magnetic clip for hanging the light from any metal surface. Other options may include an extra-long cord with a retractable cord reel.

Great as they are, traditional trouble lights have a few shortcomings. The main one is that they use a conventional incandescent light bulb. The tungsten filament inside the bulb can be easily broken if you drop the light, or even bump it while working on a car. You can buy “rugged” shop bulbs that have a more robust filament for a couple of bucks apiece, but even these may not survive if the trouble light is knocked loose and falls to the floor.

Also, incandescent bulbs burn hot. If you’ve ever accidentally rubbed your arm, cheek or forehead up against a hot trouble light while working on a car, you know what I’m talking about. It can burn you. It’s also a good idea to keep the light well away from open fuel hoses or other potentially flammable liquids or vapors to reduce the risk of fire. Fuel spraying from a loose fuel line connection or a hose with a leak can squirt quite a distance.

A traditional work light may also produce a lot of glare and shadows. The reflector on the back of the lamp doesn’t do much to diffuse the light, or in some cases, to direct it where you really need it. And if the light twists and turns on its hook, the light invariably ends up in your eyes rather than on the work area you are trying to illuminate.

Incandescent bulbs are also not very energy efficient. A 60-watt bulb will produce about 850 lumens of light, a 75-watt bulb will produce about 1,170 lumens, and a 100-watt bulb will produce about 1,700 lumens. This may not seem like a big deal, but in a large shop with multiple service bays, the energy usage of each and every trouble light adds up every month.

In recent years, compact fluorescent lamps (CFL) have become widely available, and the price has dropped significantly. A CFL bulb that produces the equivalent light output of a 100-watt bulb uses only about 23 to 26 watts of electricity. So a simple upgrade for a standard trouble light would be to replace the conventional incandescent bulb with a higher efficiency CFL bulb.

In addition to reducing your energy consumption up to 75%, CFL bulbs also run much cooler than incandescent bulbs (which is a real plus when working in close proximity to the trouble light). The bulbs are also fairly rugged and can last up to five to seven years — if you don’t drop and break them. The price of CFL bulbs has come down to $3 to $6 each depending on the wattage and where you buy the bulbs, so upgrading to the newer lighting technology doesn’t require much of an investment.

The only drawbacks with upgrading to CFL lighting are that the bulbs can take up to a minute or more to reach full intensity. The “soft white” bulbs have a light color similar to a conventional light bulb, while the “daylight” bulbs have a more bluish light similar to a “cool white” fluorescent tube style light.

Fluorescent Trouble Lights
Tube style fluorescent trouble lights have been around for many years in both corded and cordless versions. They offer the same cooler running, energy-saving advantages of CFL lighting. There is no filament inside a fluorescent tube to break if the bulb is jarred or dropped, so the lights are more rugged than their incandescent counterparts. The glass tube (or tubes if the lamp contains more than one tube) is usually encased in plastic for added protection. But these tube(s) can still shatter if the light is hit hard enough.

A fluorescent light operates differently than an incandescent light. There is no tungsten filament inside the bulb. The bulb contains mercury vapor, and is lined with a chemical phosphor coating. The coating glows and produces visible light when ultraviolet light is created inside the bulb by a high voltage current passing through the mercury vapor. For a fluorescent bulb to light off, the input voltage has to be stepped up by a transformer (ballast resistor). This requires some additional electronics and hardware, which adds to the cost of the trouble light. Consequently, fluorescent trouble lights typically start at around $30 and go up from there. Also, some use special bulbs that are not easy to find and are expensive to replace.

Another drawback with fluorescent lights (both tube style and CFLs) is that the operation of the light can be adversely affected by cold temperatures. The light may be slow to start, take longer to reach full intensity, or not reach full intensity at all if it is extremely cold.

Cordless fluorescent trouble lights are handy to use (provided you remember to recharge the battery after every use), but the battery will only power the light for a few hours at most with continuous use. Also, many of the cordless fluorescent trouble lights are low wattage, low light output lights that don’t compare well with a standard incandescent trouble light for illuminating the work area.

Halogen Shop Lights
Halogen shop lights are more for supplemental lighting of a large area than up close lighting in tight quarters. The main advantage of halogen lighting is that the light is very bright and very white. A halogen bulb is similar to an incandescent bulb in that a hot filament glows to produce light. But the gas inside the glass bulb contains halogen (an inert rare earth gas) that allows the filament to handle more current and glow much hotter and brighter without burning out. The bulbs are made of a special high temperature quartz glass, are usually cylindrical (about 4-6” long), and typically use 250 to as much as 500 watts of electricity. We’re talking serious lumen output with these lights.

Halogen shop lights are relatively inexpensive (typically $25 or less), and offer portability with a handle and adjustable base. The lights can be positioned on the floor and aimed upward to illuminate the entire underside of a vehicle on a hoist, or mounted on a pole fixture and aimed down at the engine compartment or any other area of the vehicle you are repairing.

Halogen light fixtures usually have a glass cover as well as a protective metal screen. These are necessary because the bulbs run much hotter than an ordinary incandescent bulb and produce a lot of heat (enough to possibly ignite anything flammable that might come into contact with the bulb or lamp).

Bulb life is similar to other incandescent bulbs, and the replacement cost is typically $5 to $10 each. Never touch the glass on the halogen bulb with your bare fingers when replacing it as the oils left behind can cause the glass to crack and fail when the bulb gets hot.

A Cooler Solution
The latest in lighting technology is white light emitting diode (LED) trouble lights. Colored LEDs have been around for a long time, and have been used in taillights and center high mounted stop lamps because of their extreme longevity (up to 100,000 hours!). In recent years, breakthroughs in LED manufacturing techniques have created a whole new generation of LEDs capable of producing white light. So white LEDs are now being used in many of the newest trouble lights.

LEDs are a solid-state electronic device, so there is no filament or vapor-filled glass tube to break if you drop the light. Because of this, LEDs are extremely rugged and long-lived compared to other forms of lighting. LED trouble lights also run cooler and produce less heat than incandescent trouble lights, and they use less energy. Consequently, you don’t have to worry about burning yourself or starting a fire with one of these. The low energy consumption also means that most of these lights are available as cordless models with rechargeable batteries. A single battery charge will typically allow six to 10 hours of continuous use.

Like other lighting technologies, LEDs have some limitations. One is that the light output of a single LED isn’t very great (typically 20 to 80 lumens depending on the grade of the LEDs). To produce enough illumination for a trouble light, it usually takes anywhere from 25 to 100 LEDs. On some models, a switch allows you to vary how many LEDs are on at the same time to increase or decrease light output (to extend battery life).

The nice thing about using an array of multiple LEDs is that the light generated is more diffused and softer. You get less glare and fewer shadows for better visibility. The color of the light is cool and has a bluish tint, but is not much different from that produced by a fluorescent trouble light.

There are also some cordless LED trouble lights that have a single high output LED mounted in a swivel head so it can be aimed like a spot light. A magnet in the base of the light allows it to be mounted on any steel surface.

Another neat feature of LEDs is that they can be mounted almost anywhere to provide extra lighting: on the frames of safety glasses, on a hat, even on the back of work gloves. A single low output LED won’t produce a lot of light, but in a really dark area it can provide enough illumination to help you see what you are doing. As for drawbacks, price is the main one. LEDs are relatively expensive because of the newness of the technology and the added electronics that are needed to power the bulbs. LED trouble lights typically sell for $75 to $100 or more.

The light output of many LED trouble lights (even those with a high number of LEDs) is also not as bright as a standard trouble light with a 60-watt bulb. The manufacturers of many LED trouble lights do not state how much light their products actually produce. This is partly because the light produced by an LED is not quite the same as that produced by an incandescent bulb, and there is some controversy as to how the light output of an LED should be measured and compared to that produced by other types of lighting.

Something else you should know about LEDs is that they glow brightest when they are first turned on. After a few minutes, the amount of light produced decreases somewhat (5-15%) as the temperature of the LED stabilizes. Also, as an LED ages, its light output will slowly diminish — but that can take thousands of hours of continuous operation before any noticeable change in light output occurs. And if an LED fails? It’s so sad, too bad, because you can’t replace individual LEDs like you can conventional light bulbs. They are hard wired into the circuit board and heat sink inside the lamp. Even so, wand style cordless LED trouble lights can provide cool, safe lighting in hard-to-reach places for a variety of uses.