Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Creating Electricity in survival situations

  1. Sep 5, 2015 #1
    I have a knife(and perhaps a utensil too? and also a plastic bottle?), im in a biome of some lattitude and longitude. I have a phone/bulb/radio/whatever needs very little energy, but they're discharged. Theres no plug anywhere, im in the middle of nowhere. What contraption should i make to be able to get enough electrical energy to charge/power these devices and contact civilization?

    Answers such as "impossibru" will be pretty much useless, answers such as "You could build XYZ, but you'll need ABC which you could find lying around/harvest, if you're lucky in location OMG." will be of help :) .
  2. jcsd
  3. Sep 5, 2015 #2


    User Avatar
    Science Advisor
    Gold Member

    You are not going to get much electrical power without having some very lucky finds in your wilderness .

    One possibility to get just a trickle of power is a sea water/fruit acid/urine battery if you can find some strips of different metals .
  4. Sep 5, 2015 #3
    This is probably the best idea to try. It would require finding some tin cans. These are now made of zinc coated steel (well, zinc on the outside and sometimes some kind of plastic on the inside). If you scraped the zinc off of one electrode (it's very thin) you'd have your two different metals, zinc and steel. Alternately, you might have some coins in your pocket. The first trouble with this idea is that without a lot of surface area you would get hardly any amps. The zinc in a regular battery is pulverized maximizing the surface area. So, if you had some pennies in your pocket, you could scrape off the copper plating and pound the zinc interior into the largest piece of foil possible (using stones, I suppose). The second trouble is that you'd have no depolarizer, and you'd only get current for about a minute before hydrogen bubbles clogged the flow of current within the batteries themselves. That problem could be partially dealt with by physically agitating the electrodes to shake the bubbles off.

    Alkaline electrolytes are better for zinc/steel batteries than acids, and you could make it fairly easily by starting a fire and mixing the ashes with water. Speaking of that, carbon should also work with zinc as an electrode, so if you could get some good charcoal from your fire, that might work.

    In the absence of zinc, any aluminum foil or packaging you could find would also work.

    I think both zinc/steel and zinc/carbon give 1.5 volts. As I said, your main problem will be very low amps. You'd have to make an authentic "battery" to power just about anything of use: a whole bunch of cells connected in parallel to get the amps you need, then some of those "batteries" connected in series to get the voltage needed.

    Wire? I suppose you'd have to cut thin strips from one of your tin cans. You're going to need a lot of tin cans, so look for an old camp ground left by poachers or half-wild mountain men.
  5. Sep 5, 2015 #4


    User Avatar
    Gold Member

    If you can find a magnet from trash or a natural magnet (lodestone), you could take that tin can wire and wind it for a coil-based hand-crank generator.
  6. Sep 5, 2015 #5


    Staff: Mentor

    In addition to making enough energy, you need a voltage compatible with the "phone/bulb/radio/whatever"

    I read on another PF thread recently that cell phone charging protocols are very picky and they refuse to charge unless they are followed closely.

    You will probably find that old fashioned devices are less picky, but that they need more energy. A 1.5 v flashlight bulb might be the easiest.

    Are you aware that numerous sources sell hand-crank radio/light combos for use in the wilderness?
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook