iPAQ Battery Pack
FA121A#AC3 - Extended 1840 mAh removable battery for iPAQ 3600, 3700, 3800, 3900, 5400 and 5500 series
Electrical power is the stuff of life for the iPAQ. Without it, it becomes simply an expansive box. Keeping it powered while on the move will become something that you will need to think about if you plan on using it away from your desk or home. One way to keep it working for longer is to add an extended battery. This comes in the form on an expansion jacket that contains a built-in 1840 mAh Li-ION battery and a integral compact flash slot too.
Installation is easy. Take the jacket out of the box and slip it onto the iPAQ and after a first charge (taking about 3 hours) you are ready to go! You charge and recharge the battery you use the cradle or AC charger as you would normally charge the iPAQ. The battery on the back of the jacket is removable in case you need to replace it but this is one weakness in my opinion. The catch seems flimsy and weak and I have had to tape the battery on both of mine to keep it secure.
The advantages of the batter are huge - battery life extended by between 100% and 135%, which is a real boost in power. Also, you get a CF slot too, which can be really useful for adding more memory or additional devices to your iPAQ. One other thing I don't like is the LED on the back that blinks while the pack is charging - this to me seems unnecessary and makes it impossible to charge the iPAQ next tot he bed at night.
The FA121A#AC3 is compatible with the iPAQ 3600, 3700, 3800, 3900, 5400, and 5500 series.
Summary: A super bit of kit well worth the money! 9/10!