For example :

the battery output should be live at all times. regardless of the input power state (assuming the battery has enough of a charge) the output power should be supplied uninterrupted, the charger (input) could be turned on and off (without disrupting the usb power output)

The battery I have ... anytime the power input is supplied, the power output goes out. When the input power is turned off and a usb device is plugged in (after the power input is already off) or the button is pressed on the unit ... only then will the power come on.

(Last edited by sfranzyshen on 11 Nov 2013, 22:06)

have you googled for "usb power bank"?

I'm not sure what you mean? Is there a difference between "power bank" and external battery, etc. ? I was hoping someone else out there had experience with this ... without me needing to go out and buy/test every usb power device out there ...

I am looking for a device that will provide a "failover" type functionality. When input from the wall charger is turned off the battery will take over without any disruption in the output power.