[BrianG]

Starting from the cord side, I see what looks to be a bridge rectifier, cap filter, an opto-isolated simple switching power supply, and the IC (labeled U2) is presumably the actual charger IC, but the top has been sanded to prevent identification.

However, I do notice the resistors used are 5% tolerance (gold 4th band). No big deal if they aren't used to "program" cell cutoff voltage or whatever, but if they are being used in the charging part of the circuit, I would have expected to see 1% or 2% tolerance precision resistors (5 bands).