PowerGen Mobile Juice Pack (External Battery Charger)?

[EscalatorKid]

PowerGen Mobile Juice Pack (External Battery Charger)?

I have an iPhone 4s, and the battery life sucks. But, alas, I'm stuck with it.

I'm going on a trip in a couple of months, and I've been searching for an external battery charger for on-the-go travel.

I've been looking at the PowerGen Mobile Juice Pack (http://www.amazon.com/PowerGen-External-Blackberry-Sensation-Thunderbolt/dp/B005VBNYDS/ref=cm_cr_pr_product_top)
Did any of you ever use one? Was it good/bad/other?

Also, since it doesn't seem to come with an AC adapter, what did you use to charge it? Can you just use the Apple AC Adapter? You can use your laptop to charge it, but since I'm not bringing my laptop, and I'll be using this for multiple devices (2 iPhones, sister's Nexus 7,) for multiple days, I can't obviously use it without an AC adapter to recharge the PowerGen.

Anyways, I'm just looking into it. Thanks for any help!

[Ophiary]

No AC adapter is very inconvenient,especially during your trip,but i have bought one external battery pack RAVPower,which has a ac adapter,it can take along with the external battery,so can charge on wall.
http://www.amazon.com/RAVPower-Dynamo-On--RP-PB03-External-Flashlight/dp/B007HUTXV8/ref=sr_1_2?ie=UTF8&qid=1342575272&sr=8-2&keywords=ravpower