You're camping in the wilderness. In the area where you have your tent, there live carnivorous man-eating scorpions which are active at night because they are afraid of light. So in the evening you are testing if your flashlight is still working, because you need it to scare off the scorpions. You see that the battery is empty.
Is this a reason to panic?
Because you have read this instructable!
You don't have a working battery anymore, but you probably do have: some coins containing copper, aluminum(from a can or a lightweight cooking set), sour body liquids(urine, or even better, puke), something that can absorb(like toilet paper but just some earth will also work), some leaves from a tree(the bigger the better), and some tape or rope.
In the last step I will tell how you can use the battery in the wild, first I'll demonstrate how to make the battery with kitchen products. Try that at home as a practice! You'll need it in the wilderness, it works the same there. For example, we'll use vinegar or lemon juice, instead of urine or puke, but it will all work(So if you find a lemon tree in the wilderness I recommend to make use of that instead of your body liquids, so your battery won't be so disgusting.)
Let's go on to the next step!
Step 1: What You Need
- vinegar OR lemon juice
- aluminum foil
- strong paper
- paper towel
- a bowl
- coins(you won't lose them!) containing copper, or copper-plated(these often look red-brown, and are mostly the coins with the smallest values, like 1,2 and 5 eurocent coins. I believe the USA one penny coin is copper plated, and maybe the 5- and 10 cent coins aswell. You can look it up)
you also need something to test the battery, like a bycicle light, or a multimeter.
Step 2: Making It
1: Roll up the paper with such a diameter that the coins fit in.
2: Tape aluminum foil on one side.
3: Make aluminum chunks of about the size of the coins. Make the same amount as the amount of coins you have.
4: Do the same with pieces of paper towel, then let them absorb the sour fluid.
5: fill the paper tube. Begin with a piece of paper towel, then a coin, then the aluminum. Repeat this till you filled the whole tube.
6: End with a coin
Step 3: Testing the Battery
What you see is an electric current based on a redox reaction with copper and aluminum in a sour environment. If you're not familiar with redox reactions you can learn more about them here.
Step 4: Use It in the Wild
- vinegar or lemon juice = replaceable by your own puke or urine
- tape = replaceable by rope, flexible liana-like branches, strong grass. Or maybe you just have tape with you(always take tape with you on camping!)
- aluminum foil = replaceable by the aluminum from food-wrappings, cans, if neccesary from your lightweight cooking set, or anything else lightweight, which is often made from aluminum.
- paper = replaceable by leaves. You have to wrap them around eachother to make the tube, so big leaves are the best.
- paper towel = replaceable by some earth, because it should just hold the sour stuff together.
- a bowl = replaceable by a little tamped hole in the ground.
- coins are the only things that aren't replaceable. But I think you should always take money with you on camping, even in the wild.
Most flashlights are like the one below, with two batteries in a series. This is the perfect shape to make a battery like in this instructable. If there's place for only one battery, The voltage may get too low, so you should use the space you have more effectively, if you make the layers of aluminum and sour fluid as thin a possible, then there are more 'little' batteries in the series, making a higher voltage.
It's a luck that the copper coins are mostly the smaller ones, so even for small flashlights, with AA batteries, you can make the batteries yourself.
good luck with not dieing.