Make a Powerful 9V Rechargable Salt Battery




About: Its all about life hacks, tools, scientific & creativity instructables ~ electron7m


In this instructable, you will learn how to make a powerful 9V rechargeable battery from iron nails and copper wire.The battery is rechargeable like any other normal battery and is really simple to make.

For complete understanding of the project you must watch the video.

Video -->

Credits -> creative electron7M

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Step 1: Requirements:

  1. syringe piston
  2. 12 Iron nails (better if you have zinc alloy nails).
  3. some paper strips
  4. sandpaper
  5. salt
  6. water
  7. LED lights 8 to 9 volts
  8. multi-meter
  9. screwdriver
  10. copper wire of any thickness

Video -->

Credits -> creative electron7M

Step 2: Construction: 1

First, what you have to do is remove the insulation of the copper wire with the help of the sandpaper.After doing that keep the copper wire and hold the nail in your hand.Take one of the paper strips and roll It around the nail as shown in the picture.Now simply turn the copper wire 35 times on the nail with the paper in between.Do this to all the 12 nails.

Make sure that the copper wire does not touches the nail directly.

Now take the syringe piston and make 6 holes on one side as shown in the picture.You can also use a soldering iron as I have.

For better understanding of the project results you must watch the video.

Now take the screwdriver and push the screws through the holes.Carry out the same procedure on the other side of the piston.

Do this until all the screws are installed on the piston.

Video -->
Credits -> creative electron7M

Step 3: Construction: 2

After you have completed all that was instructed in the previous step, connect all the 12 nails in series.

If you do the voltage check of this setup, the output voltage should be zero.So what you have to do now is take a plastic container filled with water and place the Piston in the water container.

Make sure that all the nails are dipped in the water if not, then add some more water.Now add some salt in it to make the water conducting.Salt water is a good conductor of electricity.

Leave the Piston in it for 2 to 3 minutes until the paper between the nails and the copper soaks the salt water.

Video -->

Credits -> creative electron7M

Step 4: Testing:

Now take out the piston from the container and check the voltage with the help of a multimeter.It should reflect 7V to 9V DC on the multi-meter screen.

You can now connect some actual loads to this homemade battery and it should work fine.

To recharge this battery, you will need a multimeter to determine the polarity of this battery and then you will have to use a 9 volt volt dc adapter to charge it.

The output should be somewhere around 0.30A to 0.40A.

Video -->

Credits -> creative electron7M

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    6 Discussions


    1 year ago

    11 ads in a 15 min video, has to be a new record haha


    1 year ago

    how this battery gave 9 V supply just by dipping it in salt water for 2-3 min ?

    1 reply

    Reply 1 year ago

    They are wired in series.

    The zinc on the outside of the nails reacts with the oxygen in the air and oxidizes to zinc oxide and also releases electrons which flow through the circuit then pass to the copper electrode and either reduce any copper oxide to copper metal or reduce the water to hydrogen and hydroxide ions. The hydrogen ions react with the air to reform the water and the hydroxide ions react with the zinc to form zinc oxide and more hydrogen ions thus the cycle is complete except for the poor zinc. Rechargeable by no means. The salt acts as an electrolyte and catalyst and the air is the oxidant, once the zinc and iron are used up, the battery dies and has to be replaced. I have built these types of batteries before and they are nothing to get worked up over. There are metal-air batteries out there that are truly rechargeable and don't need the electrodes replaced after a while such as iron in potassium hydroxide solution. Use a graphite electrode for the positive and rusty iron for the negative. The battery essentially starts off dead until its charged at a low amperage to around 0.6v per cell. It will hold its charge for months (personal experience) and you don't have to replace the electrodes. Another added benefit is that it can be made from rusty scrap iron, plant ashes, pencil lead, and water. Its basically a half cell reaction from a nickel-iron battery (a WELL tested and reliable chemistry) but instead of using nickel hydroxide for the oxygen, it uses air and water. Its a good apocalypse battery if you want to call it that. I might even do an instructable on that considering most of my instructables are about chemistry, namely electrochemistry. Robert Murray-Smith did a good video on youtube about air batteries among other things -


    1 year ago

    Great idea.

    A little point: Make sure the wire is bare copper wire, if you buy the wire with an enamel coating, or any other covering, it probably wont work.

    Have fun building!


    1 year ago

    Interesting concept. Nice project.

    1 reply