Timers that can't keep time?

[slickraft]

Is there some logical explanation why my modern, digital microwave and stove timers in the house are accurate to within seconds per year and yet my new digital pool timers lose minutes per week? I would think that the 60-cycle A/C line power would provide the time reference like my microwave and stove use to stay accurate but are these latest timers depending on their own internal clocks that aren't that accurate? I have four irrigation timers around the property and they aren't that accurate either but my pool pump timer is the worst by far.

We rarely have a power outage or brown-outs and I know when those occur anyway. What else explains the need to reset these clocks all the time? Anyone else notice this or should I just be more laid back about it? All my battery powered clocks in the garage and shop are the "atomic" self-setting and adjusting types. I'm spoiled by those!

 

[JamesW]

The clock might be based on line frequency or an internal oscillator.

If it's based on line frequency, the frequency might be slightly off or erratic. There are several devices like the Kill-a-Watt that can measure frequency.

I keep one plugged in because I suspect that the power company might try to switch over to the 50 hz standard when no one is looking.

Two unlikely causes are the clock traveling at high speed or if it's near a strong gravitational source, such as a black hole.

At speeds near the speed of light, time will slow down and you need to compensate for that or slow down to less than 0.001% of the speed of light.

If the clock is near a black hole, time will slow down and you would need to adjust for that or move the clock away from the black hole.

GPS satellites have to account for both relativistic effects to keep accurate time. Every nanosecond that the clock is off is 11.8 inches of error.

 

[slickraft]

If it is the line frequency varying I would think all of my clocks using that as a reference would show the same error. I do have grid-tied solar panels with an advanced inverter. The local power company is using my system as a test subject to simulate stabilizing the grid during brown outs or after outages. Don't know if that can affect things. I do have a Kill-a-watt I can watch for a bit.

I wish it was the black hole thing. I could use a place to get rid of unwanted stuff. It can't be from the clock travelling near the speed of light as it is gaining time. But wait...maybe it's me travelling near the speed of light. I do have a Corvair with a big block V8 in the back seat. Hmmmmm....

 

[JamesW]

I think that some clocks use line frequency and some use an internal oscillator.

Maybe it's a faulty clock. If it's under warranty, it might be worth a claim.