Warning!! DO NOT run the standard BLINK example if you have a battery connected to this board. The output of pin 13 is connected to the output of the battery charger chip STAT and THERE IS NO CURRENT LIMITING RESISTOR.
Excessive, damaging, current will flow when one output is high and the other low.
Standard Arduino boards add a current limiting resistor between the two output pins when this situation can occur, such as with the RX serial pin.