anytime you are driving with a motor, your battery efficiency will be terrible, since motors consume great amount of power. I would be looking for solid state recording devices with no moving(ie motor driven) parts.

You can incorporate, perhaps, a motion sensor that fires the camera only when motion is detected. while motor driven transports take a few seconds, even minutes, to start up, a solid state device is available practically immediately after receiving a signal to start.

So, we are all waiting for Sony's MRC1 to be sold separately, and then life will be so much easier!

Actually, for this bat project, I had access to mains power so it wasn't an issue.

there are other options besides...gulp...sony...
1-nNovia QC deck with solid state mediapak(firewire)
2-Cineform's (yet to be released) HDMI input CF card recorder
3-Convergent Design HD-SDI CF card recorder