Since my first iPhone, I’ve never had any issue with its battery life. As long as I get access to the charger by the end of the work day the battery life on the iPhone 2G or 3G have been perfectly adequate. That is until I started working on a project down in Atlanta and my weekly commute now extends to around 6-8 hours, depending on flight delays.

I began looking for battery extender for my iPhone. Initially I wanted a battery extender that can charge the iPhone 3G and 3GS, as well as possibly the Kindle. This means the ability to attach different cables to the battery. Also the ‘green’ side of me wanted a solar charging battery so that it’d be possible to charge the battery up using solar energy alone.

Unfortunately after perusing iLounge’s extensive list of battery extender reviews, it was pretty obvious that there weren’t any battery out there that would satisfy my initial list of requirements. The closest one is the IceTECH Solar i9005. With its large solar panel, large battery capacity (2500 mAh), and large collection of connector tips, it would be ideal. The only issue is it doesn’t currently support the iPhone 3GS, as Apple in its infinite wisdom has changed something with regard to charging on the 3GS.

So the search was back to regular battery extender. There are plenty of options out there but none of them really excite me. At least not at the price they are charging for. That is until I came across MonoPrice’s iPhone backup battery. With a rather large capacity (2200 mAh *) and very affordable price (~$15, depending on quantity purchased), it is perfect.

It arrived two weeks ago and I have so far used it twice. From about 10-15% charge in the iPhone, it would take about two hours to fully charge the phone from the backup battery. During that time, I was able to continue to use the iPhone with podcast playing in the background while online twittering and browsing. The only thing that is annoying is the ‘cyclon’-like blue LEDs in the front which move from left to right during the charging process (both from main to battery, and battery to phone). They are very bright and very distracting while using the phone with the battery attached, especially in a dark backseat of a taxi! To charge the backup battery, simply plug the iPhone cable to the bottom of the battery and charge it just like the phone. Unfortunately the battery does not pass the data through to the phone so you can’t sync with iTunes while charging both the phone and the battery.

But overall, the MonoPrice iPhone backup battery is priced just right and perform as advertised. High recommended if you are looking for a simple backup battery for your iPhone.

* For comparison, iPhone 3G battery capacity is 1150 mAh which means the MonoPrice battery can potentially charge the iPhone from 10-15% charge to full twice!