Battery backup for hardware clock on Beaglebone

I would like to be able to run the hardware clock from a small battery without powering the entire Beaglebone. I do not see any way of doing this. Is it possible? What am I missing?

TIA,

Dave.

There isn’t really a way to do this on the BeagleBone short of running the whole board via battery and putting it in a sleep mode, something that is not currently supported but is under development at TI…

Gerald