Bicycle Lighting/Power System

Industrialized Humans are interesting creatures. We get into our cars, speeding from place to place, burning up fossil fuels, polluting the air, spending our hard-earned money on automobile expenses and acting like the world will end if we don't get there in the next minute. We then go and pay money and spend "precious time we don't have" working out for hours in an artificially-lighted, air-conditioned gym and/or take extra time out of our days and dedicate it to jogging.

I'm not buying into that garbage...

I have begun using a bicycle more and more for transportation. It is convenient, cheap, easy to park, healthy, incredibly efficient, and fast. In a crowded urban environment it usually wins out over sitting on your butt and letting fossil fuels do the work. With the increased use, however, I needed to add some accessories for safety and convenience, namely a lighting setup.

For even more in-depth and first-hand advice regarding different lighting setups, I recommend visting Steven M. Scharf's Bicycle Lighting Systems. Also I recommend visiting his other site, Bicycle Coffee Systems.

Head Lights

The head lights are aftermarket LED running lights/fog lights designed for automotive use. I have adapted them to work on the bike by making a light bar from a piece of PVC pipe and mounting it to the head using a U-bolt. Each light unit draws about 80 milliamps from a 13 volt battery for a total of around 2 watts of LED power in the whole setup.

Inspection of the inside of the light bars showed that in each there are 4 banks of plain old 20 mA/3.2 volt drop LEDs with three wired in series per bank. This means 9.6 volts is being consumed by the LEDs with the remaining 3 or so being dissipated in a resistor. 3 volts at 20 mA is 0.06 watts, bringing the total power dissipated in resistors (going to heat not light) for the whole headlight setup to 0.48 watts. Not bad, especially considering the nearly 60 watt-hour battery I have in the system.

Once the light bars were inspected on the inside a bead of silicone was put around the edges and sealed to make them watertight.

These LED Light Bars are extremely effective for city riding where there is usually enough ambient light to ride and lights are needed mainly to make the bike visible to automobile drivers. The light bars are extremely bright when viewed head-on, and they produce a wide beam with a unique blueish-white light that drivers will see easily. They do not, however, produce a far-reaching beam that would be effective for riding in areas with no ambient light. I may add a halogen fixture later on to deal with this issue if it becomes of significant importance.

Battery Box/Housing

The battery box is a plastic "Project Enclosure" purchased from Radio Shack. It contains the battery, wiring, fuse, and associated equipment and is protected from the weather. The tail light is glued directly to the rear of the box as it faces to the back.

The battery box is mounted on a luggage rack which attaches to the seat post and is cantilevered over the rear tire. This serves a dual benefit in capturing water and mud thrown up by the rear wheel and producing a place to put luggage.

A 7.5 amp automotive blade fuse protects the system; a fuse is necessary because short circuiting these lead-acid batteries will produce more than enough current to melt copper (and therefore melt/ignite most anything else). I recommend the blade fuses over anything else because they are cheap, simple, and available at pretty much every gas station or auto parts store. You could technically go for a circuit breaker, but they are more complex and if they fail replacement is not so simple.

Battery

A 4.5 amp-hour, 12 volt lead-acid battery is installed in the box. It is a bit heavy, akin to carrying a standard size brick around, but I feel it is necessary for utility. The bike isn't for racing, it's for transportation and leisure. In addition, lead-acid is still the most cost effective, reliable, and simple option. It can take some abuse, is not expensive if damaged/stolen, and gives plenty of power when needed.

Charging

Prior to building the lighting setup, I already owned a 1.5 amp 6/12 volt battery "maintainer". This intelligent charger is designed for owners of motorcycles and other engine-driven equipment to keep their batteries charged over winter. It can be connected to the battery constantly, and is more than sufficient for charging a battery of 4.5 amp-hour volume.

The charger connects to the battery box through an SAE connector. This is a standard connector in the motorcycle industry therefore it is widely available.

Power Port

The same SAE connector which charges the system also allows me to draw power out of the battery for operating accessories. I have a cigarette lighter socket with an SAE connector on the other end which allows phone chargers and even small inverters to be connected. Very handy.

Tail Lights

The tail lights are made up of two jumbo bright red LEDs mounted in a small block of wood. They are wired in series with a 470 ohm, 1/4 watt resistor. The color is unmistakable at night, since LEDs produce a monochromatic light not just white light which has been sent through a red filter.

CREATED/WRITTEN: 2011-04-07 20:38