For the type of 18650 Batteries that we use, you should just be able to just Insert them and let them Charge Automatically.
About the Only thing that I can think of is if you are just charging 1 Battery, you might want to change the Current from 1.0 Amps to 0.5 Amps. But that is just a personal choice.
By Default, your i2 will charge a Single Battery at 1.0 Amp. And if 2 Batteries are inserted, then each will be charged at 0.5 Amps.
Some like to Charge at 0.5 Amps. Because it is supposed to Extend the Lifespan of the Battery. Takes Longer to Charge though.