Brilliant tool for any #ingress
players go bag. USB power meter. Check your cables, your chargers, your battery packs, and your handsets to ensure proper charging.
As you can see, the voltage is a little low on this pack, but it can crank out as much amps as my phone will suck in for hours on end. The nonstandard method of decidinf whether devices can charge above USB spec 500ma has caused so many headaches for manufacturers and users!