Recently i built my own drone and decided not to buy a charger to try save a bit of money as a charger would cost upwards of $20. I used my B3603 Buck Converter instead. It is very handy and you can set what current you want to charge at. It first goes through a constant current stage and the moves on to a constant voltage stage. Heres how you can do it!
Step 1: The Equipment
Please support my work by using the links included. This shop ships worldwide (orders over $20 for free) and i have found them to be very reliable with fast shipping and brilliant customer support.
You can go directly to the shop here or the other one here.
A power source, i used an old laptop adapter. (Voltage: 12.6-36V)
A B3603 buck regulator Link: B3603 Module
Two Jumper cables (which fit into the balance socket of the battery) Link: Multicolored 40-Pin DuPont Breadboard Jumper Wires (20cm)
The battery you want to charge (see my DIY 18650 RC Battery here, the one in the pics)
Step 2: Connect the B3603 to the Power Source
Make sure the polarity is correct (i.e + to + | - to -)
I built an adapter using a male banana plug and a crocodile clip.
Step 3: Setting the Voltage
The voltage you set will be the voltage of the battery when the battery has finished charging. If you are charging one cell it would be 4.2V and so on. In this example i would set it to 12.6V as it is a 3 cell battery (3x4.2V).
Step 4: Setting the Amp Limit
The higher the amperage the quicker the battery will charge. Be carefull not to charge it at a higher amperage than the batteries limit. A healthy current is about 1 amp.
Step 5: Connect to the Battery
Connect the positive terminal of the B3603 to the positive terminal of the battery and the negative of the B3603 to the negative of the battery.
Step 6: Turn It On
According to the settings on your B3603 it may or may not be supplying power to the battery. If all of the LEDs are off you need to press the OK button to turn it on.
Step 7: Charging
The first phase of charging is the constant current phase.
Once the battery has charged to a certain point it will move to the constant voltage phase. At this point you will see the CV (constant voltage) and CC (constant current) LED's flashing (see video) and after a while the constant voltage LED will be solid.
When the amps have dropped to zero charging is complete and you can remove the connectors.
Step 8: Balancing the Battery
The above method does not balance the battery. If you want to balance the battery you can charge it with the method above but to a lower voltage (e.g 12V for a 3s battery). Then you can lower the voltage to 4.2V and connect it to individual cells to charge (see pics above). Once the amps have dropped to zero you move on to the next one. I find that you only have to balance occasionally but it is vital for battery safety and health.
Step 9: Charging Complete!
I found this to be a cheap reliable solution to charging my batteries.
You can also use this as a bench power supply unit.