Ok here's my question (here we go again). If a USB port on a computer puts out 5v. and 500mA and my e-cig passthru (with no battery) works just fine, why does it not work with a battery pack putting out 5v. 1000 mA? I'm not saying your wrong, I'm just thinking there is circuitry in these things that looks for a battery in the device its powering and if it does not see one then it shuts down.
Houdini, I believe Trog explained this in the other thread. Apparently, there is a difference between a device meant solely as a battery
charger, which looks for a battery to charge, and a device meant to be a battery
pack, which will power other devices, like our ecigs, or an ipod, etc. The latter are sometimes also called something like "mobile power packs", like the APC unit.
The latter types of power packs do in fact power our ecigs on USB passthroughs, as many who have the APC device can attest to, as long as they have at least 1000 mA or 1A current output. Even the passthroughs without the battery in line.
As for why the passthroughs work with the supposedly limited to 500 mA output of the computer USB port, well I'm not 100% sure. But, I have seen posts where it's been explained that the USB2 spec does allow for higher current draw. That may be a valid explanation for why some peoples' computers will power a passthrough, and some do not, as reported on other threads. Also, many have reported that a powered USB port (a separate usb port that has it's own connection to mains power) always works with whatever kind of passthrough you have.