This board is designed for small power-conscious projects, while still boasting a high output current (2+ amps!)

It is powered of a single cell Lithium Ion battery and charged via a micro USB port.

While off, the board consumes less than 2µA!  Features automatic low voltage shutoff and short circuit protection.

A red and green LED provide straightforward information about the battery. 

• Green LED On - Power Supply On
• Green LED On and Red Blinking - On with low battery
• Green LED On and Red Blinking rapidly - On with critical battery
• Green LED Glowing/Fading - On and charging
• Red LED Glowing/Fading - Off and charging
• Red LED On - Off and charged

Update 11/7/17: I'm working on a 1.8V and 5V version of this power supply with a expected completion in Feburary 2017.

Update 2/10/17: Revision 5 works great and is the final version.

Update 5/8/17: 1.8V, 3.3V, and 5V variants are complete

Revision 5

• Battery connector from JST-PH to JST-XH
• Improved grounding

Revision 4

• Increase board size (better heat dissapation)
• Add solder connection for batteries with JST connector
• Fix ISP silkscreen label
• Remove adjustable charge current
• Add R9 C9 for improved transient on load step

Revision 3

• Increase board size (traces too close to edge)
• Add adjustable charge current via jumper
• Silkscreen improvements
• Pull up/down resistors to 20K from 10K
• New LEDs
• Increase hole size for output and ISP pins

Revision 2

• Add switch for LEDs (to save power)
• Use SMT switches instead of through hole
• Add 500mA fuse for USB
• Increase output capitance to from 47uF to 141uF
• Add pull down resistor for USB sense (R6)
• Move pull up resistor R3 across switch