Daylight Saving Time

Discussion in 'Gen 3 Prius Main Forum' started by Jonny Zero, Oct 9, 2012.

  1. Jonny Zero

    Jonny Zero Giggidy

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    Does the clock on the Prius switch automatically for Daylight Saving Time? Since it has the dates too it would be easy. This is my first time switch with the Prius...
     
  2. Paradox

    Paradox Prius Enthusiast / Moderator
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    Nope, I change it manually.
     
  3. Jonny Zero

    Jonny Zero Giggidy

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    BTW my clock is a little slow. It is behind 1 min in a month. Anyone notice that?

    I know general relativity says time slows down at higher relative speed. I did not think I was driving that fast!
     
  4. Paradox

    Paradox Prius Enthusiast / Moderator
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    I didnt notice problems in my 2010, but my 2012 pip seems to loose a minute even faster than one minute a month. Maybe a minute every 2 weeks or so... It's a quick hit of one button to add on te extra minute but it is odd...
     
  5. macman408

    macman408 Electron Guidance Counselor

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    That's pretty common among all sorts of devices - it's a cost savings thing. A fairly typical oscillator used in electronics might be ±25 ppm; ppm is 'parts per million', meaning for every million seconds that pass, it'll be within 25 seconds of the right time. That sounds pretty good, until you realize that a month has about 2.6 million seconds! So there's your minute-per-month right there. (It's also not uncommon to have oscillators as bad as ±100 ppm.)

    There are oscillators that are more accurate, but they quickly get more expensive. A 25 ppm oscillator might be $1, while a 7.5 ppm oscillator might be $5-$10 - and it's still off by about 20 seconds a month. Also, these specifications are sometimes given only for a particular temperature and voltage - a car can be in a huge range of temperatures, and there's a lot more electrical noise from surrounding components than there is in many other types of systems. Most of these things can be compensated for in one way or another, but the costs get high very quickly. At a previous job, some of the computer systems we designed for telecommunications uses had clock components that cost $100 or more. That much money would probably get you a clock that'd only be off by about a second per month.

    So instead of spending hundreds of dollars to get you an accurate clock, you have to live with it if your clock is fast or slow. Many systems (cell phones, computers, radio controlled watches and clocks, etc.) instead get an accurate clock by synchronizing to some other source, typically based off an atomic clock. The government's atomic standard will be off by under a second in 100 million years, but is a bit too large to fit inside a Prius.
     
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  6. Corwyn

    Corwyn Energy Curmudgeon

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    But if you have nav (or a cell phone) you are already connected to it.
     
  7. rebenson

    rebenson Member

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    at least year I'll remember how to change it...
     
  8. RaZa

    RaZa Member

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    This post makes no sense to me at all. A $5 watch from Walmart will have better accuracy than ±1 minute per month.
     
  9. Chunker

    Chunker My name is Chunker...I wear a hat

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    you would think it could just get the time from your phone....
     
  10. Jonny Zero

    Jonny Zero Giggidy

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    Maybe the radiation from Fukushima affected the crystals. :cautious:
     
  11. macman408

    macman408 Electron Guidance Counselor

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    There are a few reasons that can explain that. First, the prices I listed are publicly available prices - I don't have the price breaks that would be given to a high-volume watch manufacturer. Cars aren't terribly high-volume, so their components are likely to be more expensive than a cheap watch. In either case, take the prices as relative. Second, a car is a much more hostile environment - it might be outside in the winter at 40 below, or it might be parked and baking in the sun in an Arizona summer. The watch will basically always be around your skin temperature, and at the very worst, you'd expect it to be at a range of temperatures that people find comfortable. Third, there is a lot of electrical noise from the engine and other components, which is not a problem for the watch. Fourth, it's a worst-case sort of thing. If it's specced to ±1 min/month, most of them will be much better than that. The spec includes variation from the worst possible combination of temperature, voltage, aging, shock and vibration, etc.

    Most watches are rated for ±15 seconds/month. Take the same crystal and use it in the wider temperature range needed for automobile applications, and you'd probably go well past ±1 minute/month.
     
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  12. fuzzy1

    fuzzy1 Senior Member

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    This also means that RaZa was comparing a typical WalMart watch to a 3-sigma Prius clock complaint. If one buys a cheap watch for every active PriusChat participant and tests them all, it is very likely that more than a handful will get the far ends of the error distribution (the 3-sigma units) and display disappointing accuracy.
     
  13. ETC(SS)

    ETC(SS) The OTHER One Percenter.....

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    The $5 watch from Wal-Mart is probably $4 more expensive than the clock that they put into the Prius, and the Wal-Mart watch will still have to be manually adjusted for DST...unless you pop for the $12 watch....which is self-adjusting.

    The answer to the question that started all of this?

    No. The Clock on the Priuses do not self-adjust for DST.
    Like Kermit the Frog always says: "It ain't easy being green."

    Deal.
     
  14. NargilFenris

    NargilFenris Junior Member

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    Iv tried adjusting my clock to the proper time but it alway seems to set itself 5 mins fast, which really is fine for me. It means I'm never late!
     
  15. phoenixgreg

    phoenixgreg Senior member

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    A simpler solution would be for Toyota to incorporate a "-" button for both the hours and the minutes. That way, you could easily subtract minutes for inaccuracies or subtract an hour to adjust returning to standard time in autumn. This would also come in handy if you drive across time zones.
    BTW, what good is the "00" button for - I could lose that one.
     
  16. Corwyn

    Corwyn Energy Curmudgeon

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    Plus, of course, a three digit clock being off by a minute does not mean that it is off by 60 seconds.
     
  17. xs650

    xs650 Senior Member

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    I haven't paid much attention to my Prius time approximator, but a 00 button typically sets the clock to the closest whole minute. When your clock is within 30 seconds of being right, pushing the 00 button when a good time souces is at the top of the minute will set your clock accurately.

    I would still prefer your solution though.
     
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