I have a couple projects i’m working on, (along with many other projects) but two of them i want to install a single 18650, or typical 3.7 - 4.2 volt Lithium cell-phone type battery pack into, but i need a simple integrated safe charging circuit that can charge the battery internally through a common 5v USB charger ( phone wall charger, Auto USB charger, computer USB port, etc.)
I seen some such circuit board chargers posted randomly here before, but can;t find them. Do anyone know of a good seller that sells a chreap, small, good, safe reliable USB to 3.7v Lithium Ion charger that has a proper regulated charging that cuts off at the usual 4.15 - 4.20 volts most lithium Ions need?
Just do a quick search for “TP4056” and you’ll find those modules and all the information here at BLF. There are some with and w/o integrated protection circuit and the ones with the original chip are hard to find, most have some clones and not all of them are as good as the original TP4056. And they are available with both mini (older) and micro (newer boards) USB jack.
Standard pragmatic Engineering principles suggest we should go to the Shelf before we go to the Drawing Board.
In that context, I LOVE my Miller ML-102!! It will take USB power to charge a battery, or give USB power to charge/power another device. The circuit board inside may be too big, but if you have the room, the easiest solution I can see would be to cannibalize one for your nefarious ends.
I installed one in a lantern with 3 cells—I used 24ga wire off the charger —with several different usb power supplies it only gets around 550 ma in the stock setup
i just need to find the 2.1K resistors to reduce the charge amps to 470ma from the default 1A.