It would not be a key chain ...
Black 2600mAh Power Bank External Power Pack Charger with own cable for Smartphone Samsung Iphone Nokia Android Phone Tablet Or MP4 MP5 (Electronics) 5
The device is a real emergency responders in your handbag when the smartphone battery is weakening. I've deliberately tested with a Samsung Galaxy S3, even if you continue phoning and texting, the battery in the mobile phone within 3 hours of 38% is charged on 97%. The charging process of the Power Bank can be monitored easily, the LED on the cable goes from red to blue over. ATTENTION: This special unit can be only for mobile use (about 2 charges). For Tabs, it is too weak! For this you should dig deeper into their pocket, a PowerRAV with at least 10,000 mAh is recommended for IntensoTabs possible by Intenso, which are bulky, but work determined at the tabs.