NightShade Electronics has debuted a rechargeable battery shield for Atmel-powered Uno (ATmega328) and Leonardo (ATmega32u4) Arduino boards.

More specifically, the lithium-polymer battery features three primary functions: a circuit to boost the battery’s nominal voltage of 3.7V to 5V; a lithium-polymer battery charging circuit; and an on-board fuel gauge IC which facilitates the measurement of battery voltage, current and accumulated charge by means of a Two-Wire Interface (TWI/I2C).

Additional key specs include:

5V output (and 3.3V when attached to an Arduino)

500 mA output (final version expected to be higher)

Integrated charging circuit

Fuel-gauge IC – monitor voltage, current and charge via a two-wire interface (TWI/I2C)

Fully functional Arduino library

On/off switch

Charges from standard Arduino power adapter (7.2-20V)

Powers Arduino while charging

The energyShield currently offers a capacity of 1200 mAh, a nominal current sourcing of 500 mA and, at full charge, a maximum current sourcing of 825 mA.

“We are looking to improving the current rating of the board to allow the energyShield to power even more demanding projects. The reason for the varying current limitation on the energyShield has to do with the output voltage (5V) being stepped up from the battery voltage (3.7V nominal),” a NightShade rep explained in a recent Kickstarter post.

“Because the battery voltage is lower than the output voltage, the current from the battery is larger than the current drawn from the energyShield at 5V. Assuming that the power from the battery is equal to the power used at 5V, the battery current (100% efficient) can be illustrated as such: I(bat) = I(out) * 5V / V(bat).”

Interested in learning more? You can check out energyShield’s official Kickstarter page here.