The ultimate mobile USB charger

I normally use a 4 rechargeable AA USB battery pack, but after the ~25 hour trip to Perth to visit MarkH, I decided that just wasn’t enough to keep my HTC glacier alive for as long as I wanted…

Eventually, I’m going to just design a board with the USB con/low voltage alarm/SMPS, etc all built in. Hopefully I can pass through stuff like airport security with it if it looks legit like that.