High intensity LED lighting has been one of the technical revolutions of the last decade. Filament lamps, that in general purpose lighting have reigned supreme for something like a century, are now being replaced by LEDs.
But using high power LEDs has never been as simple as using filament lamps - what with the need to control current by a dropping resistor or a (more efficient but much more expensive) DC:DC converter. Take the replacement of an interior car light, for example. By the time you source a LED of sufficient intensity and organise and position a dropping resistor, it’s a project that very rapidly loses appeal!
OK, so why this preamble? We recently came across a new LED-based bulb. It costs AUD$21 and it’s been developed to replace the power-hungry miniature MR16 halogen lights that are widely used in shop and domestic installations. In fact, electrically and physically, it’s a direct drop-in replacement. That means it will work off the 12V power supply in a car. You don’t even have to worry about polarity – just wire it straight in.
The light draws only about 100 milliamps at 12V and 170 milliamps at 13.8V – very low current consumption indeed. In fact, as a comparison, that’s only about one-third the power draw of a typical interior light bulb. But does that make it really dim? Nope – in fact the LED bulb is far brighter. That’s the case for two reasons: (1) it’s much more efficient at turning electricity into light, and (2), all the light is aimed in the right direction!
Not only is the LED replacement brighter and uses less power, it also stays much cooler. Finally in the list of advantages, the light output is much less yellow so things look better when illuminated by the LED light.
OK, so how do you install one of these beasts?
The LED light provides an even and fairly wide beam. In addition to car interior lighting, it would work very well as a general purpose bike headlight or handheld torch.
We chose to upgrade the hatchback lighting of this Honda. The new LED light, complete with its pins, is 45mm deep, so keep in mind the required rear clearance. (The other major dimension is diameter – it’s 50mm.)
A small screwdriver was used to pop out the lens...
...and then the body of the light itself could be removed.
A piece of grained ABS plastic was cut out and to provide better rearwards clearance, a short section of rubber hose was glued to it. The LED light was glued into the tube.
The wiring was then connected. I had available a suitable connection block but if you don’t, solder straight to the lamp’s pins or use crimp-on terminals. Insulate the connections.
The panel was held in place with a little more glue.
The results are stunning – so much more light comes from the LED assembly that it makes the original look like a feeble, yellow glow-worm....