
The iPhone is a wonderful device. I use it so much throughout the day that sometimes I feel like is an extension of myself. Sadly the batteries don’t last longer than 3 hrs. Apple has a few recommendations on how to make the most out of it (http://www.apple.com/batteries/iphone.html). Not enough if you ask me.
I’ve been reviewing a few options for extra power to use “on the go” that can keep me using my iPhone the whole day. While there are many options available in the market, I researched what I consider to be the best options based on price and performance:
100% Reliable
Mophie juice pack air™ (yes the name is a reference to capitalize on Apple’s famous laptop): This puppy promise to double your life battery and protect your phone at the same time. Is the thinnest battery extension of it’s kind. Starting at 79.95EUR is not a bad deal. It comes with a feature called “Standby Mode” that lets you choose to either use
the extra battery or just use it as a protective case. It also connects directly with USB cable so you can charge your phone and the case at the same time.
Since the mophie website doesn’t offer more than marketing jargon here is a small table to have an idea of what to expect in terms of battery life.
Standby Time: Up to 270 hours
Talk Time: Up to 4.5 hours (3G) Up to 9 hours (2G)
Internet Use: Up to 4.5 hours (3G) Up to 5.4 Hours (Wi-Fi)
Audio Playback: Up to 20 hours
Video Playback: Up to 6 hours
Website: http://www.mophie.com/product-p/1059_jpa-ip3g-blk.htm
Outdoorsy/Summertime
SOLiCharger by Solight: “Summertime and the living’s easy…” Yup you guessed it “Solar power”. Take advantage of charging your iPhone while hiking, at the beach or simply at the Beergarden (those living in Munich) with the most abundant energy available on earth: the sun. 
Starting at 39.90 EUR (I hate these prices by the way, as if we are complete morons and don’t see that is 40 bucks ) is a good offer. The adapter plugs underneath your iPhone and charges it in about 4 hrs of direct sunlight exposure. Alternatively, it can also be charged with the regular USB cable that comes with your iPhone. The phone can be used while the device is attached. If you don’t use it for a while, a built-in solar panel on the back will provide enough power to keep the SOLiCharger fully charged. However, if you are outside, why would you want to use the phone anyway.
Website: http://www.sollight.com/products/solicharger.cfm
Emergency
iGo powerXtender: is for sure an ugly-cheap-looking device. However, it will be there when you most need it. At 20.98EUR this charger will allow you to charge your iPhone using any type of AA Batteries as suppose to other similar products of this kind that will only allow the use of rechargeable batteries (something I don’t understand about these other products.

If you can recharge the batteries… can you not recharge your iPhone as well? Obviously, they want to sell you the batteries as well). If you want to use it with an iPhone you need to buy an special adapter which can take the total price up to
20EUR. Anyway, you can use your iGo on the go and stick two of your preferred AA battery brand.

Yeah, that includes the one with the bunny and the drum.
Standby Time: Up to 270 hours
Talk Time: Up to 10 hours (3G) Up to 9 hours (2G)
Audio Playback: Up to 28 hours
Website: http://www.igo.com/Accessories/PowerXtender-Charger/invt/ps002640004
Experimental
PEG (Personal Energy Generator): While it has nothing to do with “pegging” (sorry to my Aussie friends) it has everything to do with you. The more you move the more your phone will charge.

The PEG, developed by the company nPower harvests your kinetic energy to power any electronic device. Based on the Faraday principle. The energy is produced from the motion of a magnet passing through a coil, then stored in a similar battery storage as we have today. While it innovative in the mobile device arena, this technology has been successfully used to power other type of devices such as watches. The company hopes this will replace mobile phone batteries altogether in the near future. This technology is already available for non commercial use and the commercial will ship on 2011 as they predict. If you go to their website is possible to pre-order the PEG, however is difficult to tell how good this product will really be.
Website: http://greennpower.com/