A question about the Canon battery charger (specificallyfor the "5L" battery and that comes with many of the SD series cameras and is one piece with the plug in prongs in back)
When the light turns green, has the charger shut off completely? (As opposed to still charging although at a reduced rate)
I did notice that if I unplugged the charger and a minute later plugged it back in, the light is red again.
I ask because some batteries, particularly off brand equivalents, have been reported to not hold much of a charge anda fewof those have improved their performance after getting a good long charge. So if the charger shuts off when the light turns green, then unplugging and replugging it will resume charging. (Of course this needs to be done cautiously and for the off brand batteries, some trial and error is needed to figure out how many times to unplug and replug without overcharging)