It's a simple work to transform Smart Phone Charger to a 18650 Li-Ion Battery Charger as following steps.
- Remove label of the back side and unscrew 2 screws with Philips #1 Screw Driver.
- Open the slicing cover and remove it - just apply force to un-track.
- Cut away about 17mm of top halves like photo. Cut a bit more edge side to fit in the 18650 Battery. I have used 4" Angle grinder for rough cutting, trimmed with cutter and finished with files.
- Provide a negative terminal, possibly a spring metal but good normal >0.5mm tin plated steel sheet.
- Make V cuts(@4 places) bottom side for heat-and-push-in with soldering iron.
- Provide positive terminal in proper size and glue to the proper position. I have used a piece of sponge double side tape.
- Soldering positive terminal to B+, negative terminal to B- and a 1.5k Ohm 1/4W resistor between sensor terminal(middle) and B-.
- Apply a piece of masking tape, not to make short circuit with the resistor.
- Assemble it.
- Because of the lost of one coupling part of the two halves, cut side would be loose - apply a drop of super bond to secure it.
- The power source should be connected after installation of the 18650 Battery. - Because of the soldered 1.5k Ohm sensor circuit, we are cheating the circuit.
The charger works perfectly because the similarities of the battery capacities, Galaxy S and 18650.