I'm trying to work on the camera/battery issue.

The only thing I've found so far is to cannibalize one of the regular camera batteries to power it with the external lithiums. Not ideal.

http://www.rainydaymagazine.com/RDM2006/RainyDayProjects/BatteryAdaptorProj/RDP_CanonExtendedBattery.htm

After much debate, Preston and Beth concede that going with the mod on the above page is the way to go.

Bre ordered batteries to be modded. They haven't arrived yet.

Voltage to the cameras (the elphs) can't exceed 4.2 volts.

And it shouldn't drop below 3.6 volts.

A voltage regulator or a diode can solve this problem.

Of course, an alternative is to use cameras that take AA batteries and use the lithium iron disulfide batteries in them. But those would have different optics.