The important thing about any Cell Charging is to stay within it's voltage range --The bad thing about Li-ion is if the charger keeps going well over 4.2v they can go BOOM --- also something to thing about is how low will you be discharging these cells
They have several charging circuit boards that use a simple 5v USB connection also
OK, so this is getting more complicated, but if I placed the chip you have shown above into an 18650 3P battery pack, I would have both over-charge and over-discharge protection, correct? I presume the micro USB port can be used for discharging as well as charging the batteries in the pack.
The dual-speed motor I'm driving is rated for 3 volts @ 500ma, or 1.5 watts. On the lower speed setting, the motor "sounds" like it does when powered by the 3 volts that two fresh D-cell batteries provide. On the higher speed, it sounds like it is running noticeably faster than it normally does with D-cell batteries. I presume this is because the 18650 cells operate at a higher voltage. When on the lower setting, the higher voltage, combined with lower amperage, "sounds" like it's pulling around the 1.5 watts you would normally only see on the higher setting.
The charging board/protection circuit listed above would require me to have a DC-DC buck converter to bring 5v down to 3v, nominal, for the output. I am certain I would not be able to run this 3v motor at 5v for very long, even on the lower of the two settings. I would also have to find a way to go from micro USB out, from the battery pack, to 5.5x21mm in, to power the motor. I am not finding any connectors/cable with that particular combination.
I did find a similar board (below) that has both a standard USB-A port and the micro port. Either could be used for charging and the standard port could be used to power the motor, with a readily-available USB to 5.5x21mm adapter cable. I still have the problem of too much voltage, though.
I'm starting to think this isn't going to work with the 3P Li-NMC pack I built. I have shipments coming with 21700 and 32650 cells. I'm thinking either one of those, in a single-cell configuration, will do what I'm wanting to do. If I can buy/make a container for them that makes it easy to remove the battery and place it in a dedicated charger, it might be a lot better than what I'm currently trying to do.