Battery Powered Lighting using Super Bright LEDs


The Peasant has been experimenting with those new high intensity (8000 - 11000 mCD) white LEDs for battery powered lighting. Hopefully, those smelly, dim, and dangerous coal oil lamps can be finally retired.

A couple of LED lamps in action.

Both of these lamps sit directly on top of a 12 volt 2.7 amp-hour SLA battery. One lamp has two heads that can be set at various heights and positions; an old radio antenna provides the extendable support rod. This lamp works well on a dining room table or a picnic table. The other lamp makes a great reading light, with an adjustable head angle.

Each lamp head has it's own power switch. A connector for charging the battery is also included.

The larger heads have 15 LEDs each, and the smaller head has 9.

The LEDs themselves are wired in series in groups of three, with each group having it's own current limiting resistor. The resistor is chosen to limit the LED current to 20 - 30 mA at maximum voltage. In this case, absolute maximum battery voltage is about 13 volts. This is not affected by any battery charger voltage, as the lamp switch is wired to disconnect the lamp when charging.

Battery life is almost as important a concern as lamp brightness, so I settled for close to a 20 mA draw at 13 volts. A 150 ohm resistor set this just about right. At this level brightness was quite acceptable, and battery life should be at least 14 hours for the dual head lamp, and a whopping 45 hours for the reading lamp!

Well, I guess it really is time to ditch the coal oil lamps, these LED lamps are far brighter, safer, easier to use, and they produce a much nicer color of light. With the cost of high intensity LEDs dropping to bargain prices, it really is an easy decision!

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I recently obtained some 21,000 mCD LEDs, and have found them to be even nicer yet. Here is a really handy, compact one-LED flashlight. It uses three AAA batteries and fits easily in a pocket or just about anywhere. A 56 ohm resistor and small slide switch mounted on a small circuit board fastened to a battery holder with some small bolts is all it takes!

Going to the other extreme, here is a lamp that I built using 39 LEDs! This was built using a ping-pong ball sliced in half, the LEDs mounted and glued with epoxy on top of one half, a resistor wired inside, and that glued and wired to a circuit board with a switch.

The whole assembly fits on to the connectors of a SLA rechargeable battery using female fast-on lugs soldered to the pcb. A small strap is wrapped around the battery in order to hang it from a hook in the ceiling (or a tree branch outside).

This lamp puts out plenty of light for a small room, plus it makes an excellent cordless trouble lamp as well!

For information on more LED lights, check out High Intensity LED Flashlights and Multi-Color Displays.