Designed and assembled a single cell liion battery charge/pcb that fits a single 18650. I used the recommended circuit diagrams from the chips datasheets and even the recommended NMOS fets for the protection circuit. There's three of them, but two of them are not working properly.
Normally, if you plug in a 5v USB, or just 5v, the batteries should start charging up until BAT hits 4.2v and the charger drops into standby. If the battery voltage exceeds 4.3v and below 2.8v, the protection circuit should shut off the battery output. It is also suppose to include over-current protection, so I used the FET's the datasheet preferred.
-One has problems not resetting the protection circuitry when 5v is applied, regardless of battery voltage. -On the other, the STC4054 charge IC will drop about a volt between BAT and Vcc and put about +2v on Vcc with nothing else connected.
It may very well be the case that I've got some dead IC's, but I want to make sure it something stupid I did rather than a bad circuit design or missing protections. I can't find any bad solder joints though.