Sometimes a project calls for using a wall wart and battery power. For example if you’re testing a wireless node, it would be convenient to have it run from a USB supply during the initial build, but for field testing switch over to battery power.
LifePO4 with motor
Cobbling together some questionable mobile power source just for this very reason takes time and energy away from the meaningful prototyping at hand. What you really want is a portable, rechargable option. The LiFePO4wered/USB board is an interesting offering in these circumstances. If you’re already planning to use a Lithium battery to power your 3.3V design this is probably the perfect addition to your prototyping tools. It’s a 3.2V 550mAh battery and integrated charger. The type of battery used is a LifePO4 which is an interesting piece of technology in and of itself.
The LifePO4 battery is based on lithium-ion chemistry but has several advantages over other lithium-ion based batteries. The cell has a near constant voltage of 3.2 volts during its entire discharge cycle, perfect for use with 3.3v micro-controllers and avoiding the use of voltage regulators. Due to the fact that the cell maintains this pretty constant voltage, you can draw every last bit of power out of the battery before the cell voltage drops too low.
