0.3 oz flashlight

[Mike Barney]

Here’s my homemade ultralite light:

It weighs 0.3 oz, and is bright enough to read by and illuminate my tent or walk with.

The battery is a 3.6V lithium cell, 1.1 Amp-Hr 1/2 AA.

The LED is a 3.6V ultrabright white LED. It has been carefully squished so that the leads touch the right part of the battery at the right time.

The “case” used to be on the end of a tube of chapstick, and was precision machined with a soldering iron.

The switch is a slide switch: Slide the case forward for off, or back against the battery for on. You can see on the side of the battery the plastic covering was melted to provide a contact point.

It lasts about 15 – 20 hrs per battery, and the voltage droop characteristics of the lithium cell is pretty flat.

Total cost was about $4.

[Jason Klass]

Cool idea! Doesn’t one prong of the bulb have to touch the back end of the battery? I see some solder on the side of the battery. Is this to make contact with the negative end?

[Ken Helwig]

impressed!! Awesome idea!!

[Mike Barney]

Looking at the second picture Jason, the ‘solder’ you see is actually where I used a soldering iron to gently melt away a very small part of the plastic insulation covering. One lead is bent to wrap around to the side of the battery and contact where you see the plastic cut away, the other lead is wrapped in a spiral immediately under the LED to contact the positive terminal.

I thought about making a bunch of these, but not sure how much interest there is.

MikeB

[David Lewis]

Any idea what the battery life would be?

[david chan]

Mike, “…. and was precision machined with a soldering iron.”

Thats my kind of engineering. Lets have more please.

David

[Mike Barney]

Hi David,
Battery life depends on several factors, the biggest is the current draw of LED I put in it. The original should last 15 + hrs, as pictured.
I have some brighter LED’s I got from Hong Kong which based upon the specs, probably go 8 – 10 hours, but haven’t exhausted a battery on them yet.

MikeB

[Mike Barney]

Hi David,
I should have specified that was with a 2 stage 35W $4 soldering iron, using the high heat level. The part I liked the best though, was the perfect fit top I got at a trade show, from a company who was handing out chap-stick knockoffs with their logo on it.

I could start a business if anyone need a bunch of unused chapsticks without the tops. <(;->)

[david chan]

Now you disappoint me Mike. I would have expected you to make ultra-lightweight backpacking gear from the topless chapsticks.

David

[paul johnson]

Very clever design. Good thinking. I like it.

[Mike Barney]

Tried it, but in the summer, the frame gets much lighter, but it also gets too soft when the chapstick melts and runs down your back. (but you’re butt and legs won’t get chapped) ;)

[Yukio Yamakawa]

Alkaline　Battery　23AE　（12V DC)

It is @50  at AKIHABARA   (TOKYO)

clip & wire     total  16g

for   PETZL TIKKA

It is good for 3days.

[Author]

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