charging via USB from anything below 1/2 battery level is going to be an all day affair.
Granted, this might not be a good idea without alert dogs, working smoke detectors, the safety features built into the power supply and being a natural light sleeper, but I think I'll be alright doing it this way.
I wrote this in the other thread:
Ok. put the meter on the RX200, it is drawing just under 1 amp when charging. Divided by 3, for the number of batts, each batt is charging @ about 300 ma. This will give very good battery life, but take quite a while to charge.
I'm actually happier about this rate, as it is unlikely to stress the chip too much. Compare the size of a ciruit board in a intelligent external charger, and then the board in a typical mod, and the charger board dwarfes the mod board. The mod board has a lot more functions to accomplish than the charger board, so why are charger boards bigger? They are bigger because they need components capable of handeling hight current to achieve faster charge rates, and to do that, those components that run at higher current/temperatures need to be bigger, and thermal protection and heatsinking need to be design considerations. At lower current, not so much.
I will continue to USB charge the RX, overnight once in a while, using a 750 ma usb charger. that gives me about 25% headroom for the charger circuit. I think its fine with this mod, and the RX is the only mod I will USB charge so far.