Do anyone use Power bank or external battery case?

My iphone 4S can not support whole day use as the battery nearly drain .



So I searched iphone 4S external battery in amazon and find Plush cartoon toys power banks AD below. The price is 29.99$ 5200mAh.



amazon.com /Constellations-Thunderbolt-Incredible-Blackberry-Fashionable/ dp/B00DJ3DZK2 (avoild link, delet url space when past in IE)



Also I found a external battery case here :



amazon.com /Power-External-Protective-Battery-iPhone/ dp/B00409E4JK/







The battery capacity is only 1700mAh but can be used as a case protector for iphone 4s







Which one I should bought ordo anyone find the similar high capacity like 10000mAh but cheaper one in ebay buy.com or amazon and other place?

via Forums de téléphone cellulaire (en français) http://cellphoneforums.net/fr/apple-iphone/t363406-avez-utilisation-quiconque-banque-d-alimentation-ou-cas-de-batterie-externe.html