2000 Hour Flashlight

Well...almost 2000 hours

From instructables.com, instructables.com and The Amazing 2000 Hour Flashlight, we liked the modifications. Here is how one turned out.

Buy an Eveready 5109LS at your local store for about $5. This is NOT a small Everyday Carry Flashlight. The Eveready 5109LS is a lantern type flashlight that runs on a 6 volt battery. An Eveready 6 volt Super Heavy Duty Battery is included. The Eveready 5109SL has 3 LEDs and is rated at 25 lumens. That is adequate light for camping and is way more than enough light to move about a house at night, find emergency items you need, and do all kinds of tasks.

Our flashlight was marked 10X and showed a 130 hour runtime instead of the 5X and 64 hour runtime on the stock picture.

Buy a 5-pack of 150-Ohm 1/2-watt Resistors from Radio Shack for $1.49 per 5-pack. Radio Shack stock number is 271-1109.

The Hack (Modification)

1. Unscrewed the Black Ring and remove the Lenses Assembly.

2. Using a pair of wire cutters cut the longer Red Wire right in the middle.

3. Using a pair of wire strippers strip 1/4 inch of coating from the end of each wire.

4. Using a micro screwdriver that was a little less than 1/16 inch in diameter (you could also use a small drill bit), wrap each of the resistor wire leads around the screw driver to form a coil, leaving about 1/4" uncoiled on each end.

5. Insert one of the stripped Red Wires into the coil on one side of the resistor. Using a pair of needle nose pliers, crimp the coil making sure you have wire to wire contact. Repeat the process for the other Red Wire and the other coil of the resistor.

6. You can solder it or wrap it with black electrical tape. Conductive wire glue is available at Radio Shack, for about $5.

Output Results

Modifications: 150-Ohm Resistor. You don't need 25 lumens for most tasks, 5 - 10 lumens is plenty (1 - 3 lumens is plenty to read a book).

Each of the three LEDs in the Eveready 5109SL needs about 20 milliamps to be at full 25 lumens power. Based on a visual comparison in a dark room it produces about 15 lumens of light, which is just about right.

Run Time Results

The results based on testing done by Ron Brown for his eBook The Amazing 2000-Hour Flashlight were based on how long the flashlight could run before it output less than 2 lumens. I've provided information several times from Ron Brown's eBook. It is an interesting read and definitely worth the cost of $.99.

The unmodified Eveready 5109SL just as it comes from the store = 250 hour runtime with output of 2 lumens or more. That is equal to over 4 hours a day for 2 months. That is a crazy good $5 flashlight.

The instructibles.com hacks are different ways of soldering the resistor to the lenses assembly. This method doesn't require any wire stripping or the coiling the resistor wire leads.

The Eveready 5109SL with this 150-Ohm modification = runtime with output of 2 lumens or more = still to be determined. We are confident that this will be at least a 1000 hour flashlight. Even running it 24 hours a day, it is going to take 42 days to burn the battery out, we'll keep you posted. 1000 hour runtime is equal to over 4 hours a day for 8 months. That is an even crazier good $5 flashlight with a $.30 modification.


Other Modifications

So far we have been using the Super Heavy Duty Battery that comes with the flashlight. An Alkaline Battery last longer and stores more power than a Super Heavy Duty Battery. The cheapest 6 volt Alkaline Battery is about $6 at Wal-Mart. A replacement 6 volt Super Heavy Duty Battery is $3 at Wal-Mart. Will one Alkaline Battery last longer than two Super Heavy Duty Batteries? Don't know and don't want to wait 3 months to see if it does.

You only NEED ONE 150-Ohm 1/2-watt resistor -- the picture shows TWO other-ohm resistors

We love this idea, but what about rechargeable Ni-MH AA batteries. What if there is an extended emergency and you can't find a 6 volt replacement battery? Rayovac makes a 6 volt Battery Adapter to convert 4 D cell batteries into a 6 volt battery. But we prefer AA batteries not D Cells. Try some battery adapters like: "D"s to AA or "C"s to AA. Or the La Crosse BC1000 Alpha Power Battery Charger which comes with 4 adapters that let you use AA batteries in place of D cells.($60) The Rayovac adapter includes 4 D cells. Currently $5 shipped.

Four D Cells will give you about 200 hours runtime. Four AA batteries will give you about 100 hours runtime.

Finally, did we mention that this crazy $5 flashlight also floats.