Diamond Power Save Mode

[Fua]

I work underground every once in a while and there is no reception. My Diamond appears to keep searching for signal and wastes a ton of battery.
I used to have phones that would "shut down" the radio for some time if there was no reception to conserve power.
Is there a "power save mode" or something similar for the Diamond that would prevent it from killing battery when there is no reception?

Thanks.