Any unregulated power source (battery pack, solar cell, or power adapter) can be connected via the DC power adapter port of the SPARK SLS as long as the input voltage is within the range of 5 to15 VDC. The recommended external voltage is 12 VDC. As the input voltage approaches the lower limits of this range, the rate of battery charging will diminish. Input voltages in excess of 15 VDC will damage the interface.
The power connector to the SPARK is a center-positive 4.75 mm (OD) x 1.7 mm (ID) barrel connector as shown below: