One of the very first items that I reviewed on iPhone J.D. was the RichardSolo 1800, an external battery for the iPhone. The company sent me a review unit for free, and 18 months later it is still working great for me. I cannot even begin to count the number of times that I have been out of the office all day in a deposition, in court, on a plane or in a CLE and that battery has allowed me to get through the day without running out of power on my iPhone.
The full retail price of the battery is $69.95, although you can get it on Amazon for only $40.99. But now through Monday, you can buy the unit on the RichardSolo website for 50% off, only $34.98. Or if you buy two or more units, they only cost $29.73. I believe that you have to pay for shipping, so if you have Amazon Prime it might still cost about the same to get it on Amazon, but whether you pay $35 or $40 for this battery, it will be well worth it for you.
If you don't currently have an external battery for your iPhone, I encourage you to get something like the RichardSolo 1800. Toss it in your briefcase or purse and you'll never have to worry about running out of battery power on your iPhone before the end of the day — unless you are REALLY going to be using your iPhone all day long, in which case you might want to carry two of these with you.