I use a timer application that does some precision timekeeping over several days, and I have been watching how it stays in sync with The Official NIST US Time Widget - HTML5 for cross-platform devices to see how good it really is. Yesterday afternoon (Thursday) it was 5.0 seconds off the standard, and today (Friday) it's 0.0 seconds off. I keep the battery above 75% when doing precision timing, and I think only the temperature has changed significantly in the last 24 or so hours, being inside my winter jacket with me when running around town with company. The battery application usually says it's at about 22C, and now it's at about 26C, so I wonder if the higher temperature has the clock running faster? Maybe I should leave it in the freezer for a day?