Backup Battery life and the CMUCam

[PhilBot]

Does anyone have a definative reference for how the "backup power" circuit runs through the RC unit to the perhiperal devices (PWM, RELAY etc.)?

The "standard description" of how this works seems to be that the 7.2v battery is used to deal with sags in the main 12V supply, but that doesn't seem to be the case.

I've noticed that when I power the CMUCam off a PWM output (as recommended), after a moderate time of camera testing (with no other major loads) the camera stops communicating until I replace the backup battery with a fresh one.

I would have expected the RC to be powered by either the 12V or the 7.2V via diodes. So if the 12V is good, the 7.2V battery won't get drained... but that does not seem to be the case.

Unless this is just a matter of me using an incorrect output to power the camera, this is pretty annoying, since the rules don't seem to permit me to substitue the old-style AA NiCds with NiMH barteries that would give me better camera life.

I'm just trying to find a reliable way to ensure that the camera keeps running as long as the RC runs.

Is there a better "legal" way to power the camera? maybe run the camera off the 12V supply directly. Is it just as simple as me installing my own 5V regulator?

I know... a lot of questions.....