PowerGen PGMPP6000 External Battery Pack High Capacity 6000mAh Power Bank Charger Dual USB output (w/imbedded Micro USB) for Apple iPhone 5 (Lightning Cable NOT included) iPhone 4s 4 3Gs 3G, iPod Touch, iPad 2 3/ HTC sensation, XE, XL, One X S V, Thunderbolt, Inspire 4G , EVO 3D, EVO 4G, Desire S Z HD / Samsung Galaxy S3 S2 S 2 II ACE Mini, S Advance, Galaxy Nexus, Nexus 7 / Motorola: Atrix 2, Droid 3 X X2 Razr Bionic, Triumph - WHITE

I needed an external charger for my HTC One X for when I am travelling and a power source is not readily available. I did my research and bought the smaller version of this one but was offered an upgrade which I took.
Firstly this was smaller and not as heavy as I was expecting (one of the reasons for choosing the smaller one), but found that it feels well built and sturdy.
When I received the item I immediately turned it on and was shown 3 lights which means it was 75% charged so I could have used it out of the box, however I charged it overnight so I could give it a proper test.
Over the last few days I have been charging my phone only using this external battery and was very pleased with the results. I have given the phone 2 full charges (from around 10%) and a part charge (from 10% to 80%).
I think you will agree this has performed very well and as a result I have been recommending this to my friends and family (some of which are iPhone users whose batteries are terrible).
I am very pleased I have received the larger capacity pack, this gives me peace of mind that I can use my phone heavily while I am waiting around in airports and not have to worry about running out of power, however I'm seriously thinking of purchasing the smaller version as well, which I think would be perfect for when I am on a day out (in the pub with friends etc) where it will be less intrusive in my pocket, the larger pack is fine but I would rather keep it in a bag or coat pocket maybe.
In conclusion, I definitely recommend this product, it arrived in good time and the performance has been better than expected.

I love my Juice Pack - my handbag is never without it! I get two full charges for the HTC Desire, with one full charge taking less than an hour. It takes a few hours to charge the Juice Pack, but once charged it holds its charge completely. I checked it after one month had passed, and was surprised to see it still at 100%.

It feels very nice in your hand, excellent build quality, and nice finish - really looks the part too. It is about the same size as my HTC Desire, but I don't mind that.

It has a connector for the phone that is built-in and fits flush with the body of the Juice Pack, when you pull it out to connect to the phone, the cable is rather small and appears quite flimsy, but I have not had any problems with it. The enclosed adapters fit the iPod, iPhone range and quite a selection of phones, so it can be handy when you are out to lend to a friend who's battery is dying and they need to access an app or make a call.

Brilliant when you are away from home all day and your mobile needs a boost to keep on functioning, very trustworthy!

There are times when your mobile phone battery just doesn't last long enough. If you're away from a power source for a few days, you either need to ration your mobile phone use or just give up using it when it runs out. If, like me, you go to music festivals, you have the option of paying someone quite a lot of money to charge your phone, assuming you feel comfortable with leaving it with them. What you need is a portable charger of your own.

There are some phone chargers that take ordinary AA batteries, but of course they can cost a fortune in disposable batteries. The PowerGen, which was supplied to me for review by its Amazon distributor, is the first rechargeable portable charger I've seen, and it does away with all the disadvantages of other types of external chargers.

So, when you're planning to go away, you charge your phone and you also charge the PowerGen. It charges using a USB port in about 5 hours if you use a 1 Amp supply (it holds about 5.2 Amp hours). Most computer USB ports deliver less current, and so take longer to charge it, so it's best to use a mains-to-USB adapter, such as your Kindle, iPhone or iPad mains charging accessory. I use a 3 Pin 1000mA USB Power Adapter Mains Charger. The adapter supplied with the PowerGen is a flat 2-pin plug, which is not suitable for use in the UK without a travel adapter.

Now you have a charged PowerGen, whenever your phone starts running low on power, you plug in the PowerGen using another USB cable, press the charge button, and the power stored in the PowerGen charges your phone. For my phone, a Motorola Milestone 2 Android phone, the Powergen was able to give it three full charges, enough to keep it going for the duration of most music festivals. There was enough power left in the PowerGen to give an 80% charge to a friend's iPhone as well.

To add to the festival-going credentials of this useful little device, if you press the charge button twice, you can use the PowerGen as an LED torch.

There are two identical USB cables supplied (identical except for length - one is longer than the other) that accept a variety of plug adapters to make the PowerGen work with most devices that can be charged via USB. There are micro and mini USB, iPhone and PSP adapters (so it's not just for mobile phones!), and a selection of other adapters that I don't recognise. If you prefer, you can use the USB cable that came with your device, as the "from" end is a standard USB socket.

The PowerGen is compact enough to fit in your pocket alongside your phone. If you want to charge your phone while it's in your pocket, you need to be careful with the cable-plus-plug-adapter combination, which is a bit unwieldy, and can get twisted and unplug itself. It's fine if you're careful, and the PowerGen unit itself is robust. Four LEDs show how much charge is left in the PowerGen: each LED is roughly equivalent to an hour's charge.

The PowerGen is a simple idea that can make a big difference. It's great for festivals or if you're out of the office without access to a mains socket.

Note: I have seen other reviews that suggest that the rechargeable batteries in the PowerGen have a limited lifespan. I've only charged mine a couple of times so far and it seems fine, but I'll update this review if I see any problems. It's still likely to work out cheaper than using disposable batteries.