How to Make a 12 Volt Battery Charger

A DC adapter can be converted into a battery charger.

A battery charger can be used to restore the plates within a lead-acid battery. A battery provides electrical energy by means of an electrochemical reaction between the battery plates and the battery electrolyte. The chemical reaction creates lead sulfate crystals. Over time, these crystals accumulate on the battery plate surfaces and form a barrier that prevents the lead metal from coming in direct contact with the electrolyte. One way to reverse the crystal formation is by charging the battery. You can construct a simple lead-acid battery charger from a DC wall adapter and a few electrical components.

Things You'll Need

• 2 Crocodile clips
• Permanent marker
• 12-volt DC wall adapter
• Electrical pliers
• 2 Crimp-type ring terminals
• Screwdriver

Instructions

1. Mark one of the crocodile clips with a "+" symbol.

2. Snip the tip off the adapter. Pull apart the wires until there is a 6-inch separation between the wire ends. Strip 1/2 inch of insulation from the positive wire.

3. 

   The adaptor tip is labeled to identify the positive wire.

   Place one of the ring terminals over the positive wire, and crimp the terminal to the wire. Loosen and remove the screw on the labeled crocodile clip. Place the ring terminal over the screw hole, and reinsert the screw. Tighten the screw so it holds the ring terminal to the crocodile clip snugly.

4. Strip 1/2 inch of insulation from the negative wire. Place the remaining ring terminal over the negative wire, and crimp the terminal to the wire.

5. Loosen and remove the screw on the remaining crocodile clip. Place the ring terminal over the screw hole, and reinsert the screw. Tighten the screw so it holds the ring terminal to the crocodile clip snugly.

Tips & Warnings

• To use this charger, plug the adapter into a wall outlet, attach the "+" labeled clip to the positive battery terminal, and attach the unlabeled clip to the negative battery terminal. Allow the battery to charge for at least two hours.

References

• University of Technology Sydney (Australia): An Application: A Battery Charger
• "Battery Maintenance;" Popular Mechanics; Mike Allen; August 2000

Resources

• Mueller Electric: Crocodile Clips