Step 5: Wiring it Up

Picture of Wiring it Up
Wiring on a flashlight is pretty basic. A complete circuit is just Battery Positive to Switch to Bulb and back to Battery Negative.

Since this is a rechargeable battery, it would be nice to also add a way to recharge the lantern without taking it apart to access the battery. To do that, we'll reuse the power cord port as a place to connect the charger to.

First, check to make sure the wires on the switch and power inlet will reach the battery and the bulb.

The "115/230" power switch won't be used, so its red wires can be snipped-off. Save them for reuse. It's good heavy wire, and red is typically used to indicate Positive polarity.

Strip and twist together one wire from each of the power switch and the power inlet. Add a female spade terminal and crimp it on. This connector goes to the Positive terminal of the battery. The other wire of the switch goes to the  bulb. 

The OTHER wire of the power inlet goes to the opposite side of the bulb. That side of the bulb also goes to the battery negative. This bulb has "multi-terminals" on it, so it's easy to connect two wires at once to a terminal - one with a spade connector, and one with a bare wire tightened down under a screw.

Once you are done, power will only go to the bulb when the switch is on, but power will always be connected to two of the pins of the power inlet. (Cut off the third wire.) That way a battery charger can be connected to the two pins to recharge the battery. Mark the two pins with the correct polarity.

(A note on reusing the switch: Switches and other components often have 2 sets of ratings - one for AC and one for DC. The ratings are typically much LOWER for DC. Use a flashlight to look closely on the side of the switch, and you will see its power rating. Because this is only a 1 Amp project, this switch will work fine.)

jim_lewis12 years ago
I have to echo the concern regarding reusing the power inlet.
Connecting what is clearly a mains power input to the battery terminals is VERY DUMB.
Someone, (perhaps even you in a while when you forget how it's wired), will connect this to the mains and the results will be ugly.
Good design is first and foremost inherently safe. This is an accident waiting to happen.

Sometimes a lower light level, is all you need to be able to navigate around a room.
You could use the 115/230 switch to put a resistor, into the circuit, so you  could have a hi/lo setup.