I want to design my own portable power bank for phone devices (or any USB devices).
I'm still deciding on whether I'll be using 3.7V Li-ion/Li-po battery.
Something like this: http://www.gadgetsfactory.com/aluminium-power-bank-portable-cell-phone-battery.html
It has a charging interface (micro USB) and has a standard A USB interface for discharging, such as to your phone.
Here's another one http://www.ebay.com/itm/5V-Mini-USB-1A-Lithium-Battery-Charging-Lipo-Charger-Module-for-Arduino-A866-MA-/131304520047 but I believe it only charges the Li-ion/Li-po battery and doesn't have output voltage to apply to a phone for example.
Here's one with the management system which I wish to have some feedback if anyone has used it. It's the Lipo rider. http://www.ebay.com.au/itm/1pcs-new-Arduino-Compatible-Solar-Charger-shield-LiPo-rider-/381714472087?hash=item58dff49c97:g:0FIAAOSw0RpXlvxO Any feedback on this?
Does anyone have recommendations that's similar to the Lipo rider?
I'm free for any suggestions (positive or bad).