External Battery - iPhone 4s

[kurabii]

Have a 4s and am traveling to italy with the girlfriend and just purchased this external charger:

http://www.amazon.com/dp/B009SYASSI/ref=pe_385040_30332200_pe_309540_26725410_item

Anyone know how long itll last and give me in battery? if i were to hook up my phone to it at 10% battery life? Am looking for another solution like a case battery. Looking for a good solution, cheappppp that i can use with my amazon prime account or find online with stellar or 4/5+ reviews. Anyone have an option?

thanks in advance

 

[Domini]

I believe iPhones have 1800mah batteries? The external you are buying is a 5000mah. Only you can calculate how long that would last which could be up to a week depending on how you use your phone.