#Several Li-Ion Power Supply Options A collection of Li-Ion power supply designs for embedded use.
##Protected vs non-protected Cells Li-Ion cells come in protected and non-protected variants. In general, protection is achieved by an additional circuit that is integrated into the battery cell. Most 18650 cells come as "Protected" so the core cell will be disconnected when the cell voltage falls below a certain threshold level (typically 2V5 to 3V0).
##Non-protected Cell Circuit It's based on an extended TP4056 application (datasheet) that is sold at many places. In addition to the TP4056, it includes a DW01-G (datasheet) protection circuit and a 8205A MOSFET (datasheet). This article on Instructables discusses the board in very detail: [ESP8266 - Li-Ion Battery rechargeable battery power solution](http://www.instructables.c