I love how slim and light it is, and charging by microUSB is something I dearly missed. The biggest problem is that it's a slippery little bugger. Trying to figure out how to make it more tacky so that if I'm stacking the battery under the phone, it won't slip every which way (which if you see the pictures, is how it's being used).

I wonder if they make clear, wide rubber bands...

I bought the Astro Slim2 for my niece, but I actually use the EasyAcc 5000mAh pack myself. It is a little larger than the Slim2 but same thickness. It has a rubberish outer shell that won't slip, and the micro-usb built-in connector is about half the size of the Slim2's so it would fit thru the thick bumper case of my phone. I posted up some comparison pictures on Amazon EasyAcc 5000mAh page.

Can you give me more details of Mophie Juicepacks, I've checked it from apple store and it's quite a luxury one for me. It might be my another option if I wish to switch brands.

If you are looking for case with build-in battery, there are plenty alternatives on Amazon:
http://www.amazon.ca/s/ref=nb_sb_nos...ery+phone+case

I would also recommend to consider between a case with build-in battery and a portable USB charger. It really comes down to your needs. If you need to charge your phone more than once a day on regular basis, you need a battery case for the convenience. However, if you just need extra power from time to time, consider buying a portable charger. Battery case adds extra thickness and weight directly on your phone at all times, while you can have a portable charger in your bag or car so you have extra backup power only when you need it.

There are extra benefits portable charger has over battery cases too. A portable USB charger allows you to charge all your USB devices like headset, iPod, iPad, even some models of digital cameras, not only phones. Portable chargers usually cost less than battery cases on per-mAh basis. You can easily get a high capacity portable charger but the capacity of battery cases are limited.

A 2,000mAh portable charger typically allows you to fully recharge a iPhone 5 and costs under $20. I now keep a 2200mAh charger in my laptop bag and another 4400mAh charge in my luggage whenever I travel, and this works out great. I just plug in the 2200mAh pack whenever my phone battery runs low, and I've never needed anything more than one full charge based on my usage. I take out the 4400mAh when I know I'm going to be off-grid for extended period. The chargers keep my phone, headset, iPod, and camera powered whenever needed, and serves as iPad emergency power.

Over years I've used several battery case and portable chargers:
- mophie juice pack for my iPhone 4
- mophie helium for my HTC
- duracell Li-Ion instant USB charger (small capacity, used it years ago)
- anker slim 3
- mophie powerstation duo
- nextek energy pocket boost micro and 4400
- generic cheap "power bank" purchased from eBay

Overall, mophie makes good quality cases and chargers but at a much higher price. I have used 3 different mophie products (2 cases and 1 charger) all were gifts received and I liked them. However, I would not purchase them myself because I don't think the high cost justifies for the quality. anker sells portable chargers at lower cost and that's why I bought the slim 3. However I find that the 6000mAh capacity is more than what I need and I can save space and weight going for less capacity.

My latest discovery and my favor USB chargers now are the Pocket Boost made by Nextek Energy. I really like the quality and durability of the anodized aluminum cases (same material as iPhone case) and these Pocket Boost chargers match very nicely with my iPhone/iPad. I think the Pocket Boosts are on sale now and you can get the 4400mAh Pocket Boost for under $30. I've used this coupon code to get 10% off when I purchased my two units over a month and half ago so not sure if it still works: DTQ6FIFRDULF

http://www.nextekenergy.com/products/pocket-boost-micro
http://www.nextekenergy.com/products/pocket-boost-4400

Thanks for the informative post, and welcome to Flyertalk, rickcarson913!

I use the Zagg Spark 6000. Not a huge battery, but it works for what I need (which is usually recharging the phone while in a meeting or on a plane), plus I can carry one less charger to recharge my iPad/iPhone when on the road. I've looked at a number of the 10,000mAh batteries, but haven't been able to justify the $ yet.

The original Apple AC adapter that comes with my iPhone is small enough to carry anywhere and makes it extremely hard to justify the $99.99 price tag for this one piece 6000mAh charger + AC adapter.

We're not talking about AC adapters, though. We're talking about external batteries that you can use to charge electronics if you aren't near a power outlet.

Welcome to Flyertalk, by the way!

Yep we're talking about portable USB charger (aka external battery). My comment was about the $99 pricing for the 6000mAh portable charger + AC adapter mentioned by AussieExPat - it's hard to justify the high price as you can easily carry a small ac adapter to use with portable chargers that do not have build-in ac adapter function.

and thanks - glad to join the discussion.

I use a Monoprice branded PowerRocks Stone 3 (7800 mAh). I wish Monoprice still sold them, they were a steal. ^

Just when I thought I had a brilliant idea, someone beats me to it :p

Portable charger with Qi wireless charging built-in

Free external battery charger (giveaway contest)
 

Spotted that Nextek Energy is giving away free Pocket Boost external battery chargers right now through 5 contests:

http://www.nextekenergy.com/pages/po...stmas-giveaway

I have this one.....

http://www.amazon.com/Dual-Port-Flas...ternal+battery

it will charge my 5s about 4 times if not completely dead.

I just grabbed http://www.vagabondchargers.com/#!pr...rger-micro-usb with coupon HOLIDAY it's 50% off and while it's not a big capacity battery at all I think the format is sheer win. I had a flash drive before with me anyways. I hope it's not much heavier. I often just need one more hour with Google Maps to get home :) and this will do just that. I still have a huge Romoss for other scenarios.

I bought that mugen battery and I LOVE IT! Perfect for travel. Leave it bedside at night for pick up the phone, put it down. Then, when I leave the room in the morning, I just connect it to a charger. It was a true game-changer for me in my mobile workflow.