Notes from Windward: #59

12 Volt DC Lamp

12 volt bulb with wires attached
Here's a handy way to make up an emergency/camping light for just a few bucks.

Automobile tail lights come in two types: single filament and double filament. You can pick up a single filament bulb at your local autoparts store, and they're commonly available in most grocery stores.

Then stop by Radio Shack and pick up some speaker wire and a pair of battery clips. Make sure that the clips are large enough to clamp onto a battery terminal, but you don't need to get the heavy copper clamps that are used in automotive applications.

The wire needs to be soldered to the bulb, and here's how you go about doing that. The key to the process is what's called "tinning" the wire and bulb.

It's a three step process. First take a soldering iron, melt a drop of solder on the tip and then touch the molten solder to the shoulder of the bulb's metal base, holding it there until it "wets" and flows. It's important to get a good bond between the solder and the metal base of the bulb.

Now repeat Step One, only this time you're going to get a drop of fresh solder to adhere to the leaded terminal in the center of the bottom of the base of the bulb.

Step Two involves tinning the wire. Split the speaker wire in two, and strip back about a half inch of insulation from each end. Heat the end of the wire with the soldering tip until the solder soaks into the wire.

Now we're ready for Step Three. Lay one of the tinned wires over the spot of solder on the base and apply the hot soldering iron just long enough so that the solder joint flows between the wire and the base. Repeat with the other wire, attaching it to the solder spot on the terminal.

Next, we're going to repeat the tinning and soldering process to attach the battery clips to the other end of the speaker wire. Note that it doesn't matter which wire is soldered to which terminal, and while it may be possible to mechanically attach the wire to the terminal, I'd recommend going ahead and soldering the wire on. That will prevent it from coming lose or from losing its connection due to corrosion. When you're making something that you might need in an emergency, you want to be as sure as you can that it'll work the first time every time.

the battery clip with wire attached
I like to use this set up for lighting when I'm camping. Propane lanterns put out a lot of light, but I find them glaring and they make a hissing sound that, for me, spoils the restfulness of the camping experience. Tail light bulbs don't give out as much light as a propane lantern, but it's more than enough to read by and you can use it for hours without drawing your battery down noticeably.

When I camp, I bring along an RV "deep cycle" battery to power my lighting system. An RV battery is designed to be drawn down to a low level of charge without being damaged, so using it to power your lighting system isn't going to hurt it. Also, I don't have to worry about not being able to start my vehicle later.

Other advantages of 12 volt lighting is that it's safe around kids, and can be used in a damp environment without risk of shock.

Once you've played with your 12 volt lamp, and seen how much light they really do put out, you might want to consider installing 12 volt lighting as a back-up lighting system in critical areas such as the kitchen. By powering your kitchen lighting off of an RV battery, and then trickle charging the battery from the wall current, you'll have a lighting system that will work during power outages. When the grid fails, for whatever reason, the first thing you need to do is get some light to work with. After that, it's all down hill.

Any battery will eventually run down, but you can build your own 12 Vdc generator to recharge your battery. For an nifty website that offers instruction on doing just that, Click here.

Other options for recharging your RV battery include a photovoltaic array, or even an alternator mounted on a bicycle. For information on pedal power Click here.

This light is also very handy when you get a flat tire on some dark night. Having a movable light source that you can use to rummage through the trunk, or use to make sure that you've got the jack in the right spot can ease a troublesome task considerably. Also, if you're working on a tire at night, the more light you can surround yourself with, the better.

In this modern age, we use electricity for lots of things; some are trivial, while others are essential. A strong argument can be made that the most fundamental changes in modern life came about because of the development of electric lighting.

Until this century, the world at night was lit only by fire, and winter was a time of almost perpetual darkness. A 12 vdc light system can be your first line of defense against the night.

Notes Issue # 59 ---- The Windward Home Page