This project was inspired by a friend who lived close to a motorway junction, on a main road into the nearby town, the road was a long sweeping bend on a downhill run, and he had to park his vehicles on the road, he had many vehicles hit his, mainly at night or during bad weather.
He had two choices, leave his sidelights on all night and flatten his battery or look for an alternative, my solution was two parking lights which were LED lights, one red and one white, and both fitted to the offside of his vehicle as he parked with the nearside on the pavement.
To begin you will need the following - 3 X white LED's; 5 X red LED's, two 24 ohm resistors;as well as some scrap material most of us have lying around.
The LED specifications are as follows - white, 40,000 mcd, 3.6 V forward voltage, 20M/A current draw; red, 25,000 mcd, 2.3 V forward voltage, 20 M/A current draw.
To begin i found some plastic pipe of 25mm outside diameter, this was cut to two 40mm lengths, i found some clear lexan 2mm thick plastic which was cut and bonded inside the pipe to form the clear lens.
Two pieces of plastic were turned to fit snugly inside the plastic pipe, these were drilled with 5 X 5.2mm holes to accept the red LED's and three X 5.2mm holes to accept the white LED's.
I found some thin aluminium sheet and cut out two circles the same size as the plastic, these were buffed to a shine on one side and abraded on the other, both plastic discs were abraded on one side and the aluminium discs were attached using quick setting epoxy adhesive, once dried the aluminium sheet was drilled through.
The LED's were installed and the wires cut to length, ther were soldered in series to exploit the voltage and keep the current consumption down, a black wire was soldered to the last negative terminal of each LED, and the resistor was soldered to the positive terminal of the first LED in each light, and a red wire soldered to it.
The base plates with the LED's were now complete and were connected to the car battery to test them and ensure they worked correctly, and they were pushed into the pipes until the LED's were about 1mm off touching the lenses, epoxy was used to glue them into position, once it was hard the remaining cavity of the pipe was filled with polyester resin. This sealed the pipes to form a waterproof red rear light, and a waterproof white front light.
Installing them in the vehicle was simple, the outside of the pipe was abraded and a suitable hole was cut into the bumper, this was enlarged intil the tube was a tight fit, this was pushed in and several coats of polyester resin were applied to the inside of the bumper to hold it in position as it was a plastic bumper.
The wiring was run to a switch on the dashboard.
As the nominal battery voltage is 12.6 v with the engine not running, but could rise to around 14.5 V with the engine running, and potentially blow the LED parking lights if they were left switched on, a relay was fitted, this was a N/C or normally closed relay which has its contacts closed with no voltage applied. This was wired into the ignition which when switched on applies power to the relay and opens the contacts, even if the lights are left on, awitching on the ignition extinguishes them.
The total combined power consumption of both lights is 40M/A (milliamps) or 0.04 amps, so will not flatted the battery, with 10 hours use they will only consume 0.4 amps from the vehicle battery, so fine for long winter nights.
As usual my LED's were purchased from Craig at led-depot.co.uk and cost £11 for 50 red LED's and £7.75 for 50 white LED's, the remaining bits and resistors are what i already have lying around at home.
Since fitting his parking lights he has had no more vehicles hit his, and a significant insurance premium reduction.
Sun Sep 18, 2011 1:16 pm
