Recharable Tin Can Battery

Rather than throwing away your empty tin cans you can try making them into rechargeable batteries. They can easily be made with things you probably already have at home.

The idea for this comes from this instructable by LabCoatz . (It's well worth reading as it explains how it works). I added another layer of paper, which increases the number of recharges. I also focused on working with tin cans rather than copper pipes.

Six, 820 millilitre cans in series ran a Radio.


Executive Summary for Tin Can battery:
Results for single tin can battery .

• Output:
  
  • 1.04 volts
  • 170 mAmps (with out load)
  • 50 mW/hrs (calculated)
  • Time to charge: 2 minutes, using Phone battery pack. (5V, 2A)

• Powered the 4 motors shown for 30 minutes
• Powered LED garden light for 3 hours
• Ran the special torch shown for 20 minutes (Torch only normally needs one AA Battery to run)
• 10 recharges already made, Replacing aluminum foil will be required very shortly
• Six, 820mill cans in series were able to run a small radio for 20 minutes
• After recharging the tin can battery it should be used straight away as it has a high self discharge rate

If you do decide to go down the rabbit hole and experiment with home made batteries, it is well worth investing in some Alligator leads as these make connecting things up so much easier.

• Empty Tin Can
• A4 paper
• PVA glue
• Salt
• Water
• Aluminum Foil

• Add a cup of hot salt water to a container
• Add salt until no more will dissolve. (I needed about 1/3 cup)
• (If the salt water doesn't have enough salt in it, the battery won't work very well)
• Allow to cool

• Cut a piece of paper from an A4 sheet so it wraps around the tin
• Fix with PVA glue
• Wet the paper in the saturated salt water solution

• Paint the wetted paper with PVA glue
• This is the 'secret sauce' as it creates a membrane for electron flow
• Allow to dry for about 30 minutes or so

• Cover with another sheet of paper
• Dip in the salt water

• Wrap a paper towel around the can
• Dip in the salt water
• (The paper towel is optional but helps to stop the battery drying out)

• Fold a sheet of aluminum foil in half to be a double layer
• Wrap the foil around the tin can
• (Be careful that none of the foil touches the tin metal)
• Careful expose a little of the tin can to connect to an alligator clip
• It may help to start the foil a couple of millimeters above the base of the can to prevent it touching the tin
• Wrap the base of the can in cling film

I used a USB battery pack to charge the tin can battery.

• Find a spare USB to USB A lead
• Cut off the small USB A connector, exposing the wires
• There will be 4 wires: 2 for data and 2 for power
• Use the the 2 power wires to charge the tin can battery

• Connect to a DC power source which is less than 12 volts
• E.g. Connect to a USB battery pack or USB outlet, using lead made earlier
• Charge for between 2 - 3 minutes
• Connect the negative to the aluminum, the positive to the tin
• The tin can may feel a little warm while charging

If you have a volt meter you can check the output after the tin can battery has charged, although this isn't really required. The real test is what the battery can run...

Things the tin can battery will run:

A garden light (remove the battery the light came with) and connect it to the tin can battery

Small motor - e.g. tail motor of a mini helicopter

Using a dc voltage booster it will run a normal LED light - you could extract a booster from a garden light or make your own 'joule thief' - Search Instructables for instructions

Have fun experimenting with Tin Can Batteries.