It is pretty simple to test iphone battery life by measuring movie playing time. Here is the procedure
Method
1- Fully Charge iphone through AC charger. It will take 2-3 hours to
fully power up an iphone. After fully charge it up, load 11 long movies
onto iphone using iTune software, play 11 movies with non-stop mode.
Count the hours. The battery life for playing movie is about 5-6 hours
without connection with an iPhone external battery. After that, fully
charge the iphone up again, this time, connects iphone with an IMP500
iphone backup battery through an iPhone connector, play the long hours
movie and count the hours again. This time the measuring time will be
surprisingly longer, which will be 38 hours (About 10+ movies) See the
measuring table below. This IMP500 is a a perfect unique iphone
accessories
Method 2- Fully drain out the iphone battery, let the iphone battery completely drained out. Fully charge
up IMP500 iphone backup battery using AC charge. Use IMP500 to power up
the iphone. If we test the battery life this way, we found iPhone movie
playing time drop to 15 hours only if connects with IMP500 iphone
backup battery. It takes more power to power up iPhone if the battery
is completely drained out. But this model is still very very powerful
if compares with original iPhone battery, which is only 1250mAh. IMP500
holds 5000mAh battery capacity
