The Switronix V-Mount Jetpack & Battery for Blackmagic Camera Kit from B&H -- the Jetpack connects to the battery and outputs power to up to six devices, including the camera via a DC output. The other outputs are two P-taps, three Lemos, and a USB output. You can use all these to power lights, monitors and similar devices. The Lemos come in 2-pin 5V, 3-pin 7.2V, and 4-pin 12V configurations. Both the Jetpack and battery have V-mounts.
The battery is a 14.4V lithium-ion with a 98Wh capacity. It features a 4-stage LED readout that offers quick reference to remaining battery power, and it charges fully in 4-5 hours with the included PB70 charger.
The Wooden Camera rod clamp is included because Jetpack can't be attached directly to the Blackmagic Camera. The clamp will let you neatly mount Jetpack and the battery onto a rig.