Quoted from barakandl:Use the service outlet and a 3.3v - 5v. wall wart supply to power the RTC. If the power goes out, the nvram still retains settings and the clock will continue when the line power comes back.
Would need tested. The RTC is really inaccurate anyways. Expect it to drift out of time pretty fast whatever solution used.
Before somebody does it (because I know at least a few will), note to the people who use power strips/wall switches and need to figure out why their solution is definitely not working: It won't work that way obviously 
