I have a question for you extremely tech folks out there, but first some of the assumptions that I'm operating under: the battery is nominally 3.7v; my AC to DC charger for my SD1000 puts out 4.3v.
If you are attempting to charge a LiPo battery, it can be a *very* bad idea to use too high a voltage, LiPo batteries are liable to thermal runaway if the voltage goes too high, we are talking a lot of magic smoke and much flame here
(see this topic for more details).
Some of the battery voltages that were being written to the output log were 4.5v and one said 5.8v! The script shut the camera down after that (I'm assuming it was the script, but maybe there is some over-current logic in the camera...? (that's one question I have, I suppose.)
The camera may do much worse than shut down, it may "crowbar" the power supply to pop the battery fuse, so take extreme care with this. There is certainly some circuitry and logic involved that looks capable of this, I have never tried to see if my hunch about its function is correct, nor do I know what voltage would cause this, but be assured it would probably be not much more than 5.8V.
There are certain strings in the firmware that suggest the camera does indeed worry about voltages here are some examples (from the Ixus Wireless firmware).. BatVoltageToAd - LATCH_E3:VoltageDrop - LATCH_E21:VoltageDrop - LATCH_E2:VoltageDrop - SetInputVoltage - so in all probability the Digic in the camera does react to voltage problems, most probably by shutting down. The DC controller circuitry may however have other ideas about what to do, or may simply fry if the voltage exceeds certain thresholds.