My smart fortwo has two clocks, one on the radio, one in the driver’s dashboard;
Both go wrong over time, but both in two different directions, so the trick is to calculate the „average“ between both, and you end up with roughly the correct time.
Both go wrong over time, but both in two different directions, so the trick is to calculate the „average“ between both, and you end up with roughly the correct time.
What surprised me most was that the clock adjusted itself automatically whenever daylight saving time started or ended.
There was no calendar or date setting, so I assume it must have received the time either via RDS (I don't know whether RDS supports this) or through a built-in DCF77 receiver.
All my subsequent cars had far more features, yet none of them had this one.
I also wonder why cars with built-in GPS navigation don't synchronize their clocks using the time from the GPS signal. Heck, the car could even determine your time zone from your GPS coordinates, so there'd be no need to configure anything manually.
Checking wikipedia, there is optional support for transmitting time and date in RDS, with an explicit usecase of updating the clock in cars.
> I also wonder why cars with built-in GPS navigation don't synchronize their clocks using the time from the GPS signal.
GPS doesn't transmit timezone information, nor does it transmit leap seconds. It transmits a very, very accurate UTC minus 18 seconds, but without access to the internet for timezone database updates or (until recently) leap seconds, it's a bit useless for updating a clock.
Then just let the user override TZ offsets or the like if they want.
I thought I broke the clock with a DIY repair because it too couldn’t be manually set (aside from enabling a +30 min offset). Luckily it fixed itself after driving out of the garage when it found a GPS signal.
CURLY: About uh--- [Looks at the three watches on his wrists.]
MOE: Hey! What’s the idea of the three watches?
CURLY: That’s the way I tell the time.
MOE: How do you tell the time?
CURLY: This one runs ten minutes slow every two hours. This runs twenty minutes fast every four hours. The one in the middle is broken and stopped at two o’clock.
MOE: Well, how do you tell the time?
CURLY: I take the ten minutes on this one and subtract it by the twenty minutes on that one. Then I divide it by the two in the middle.
MOE: Well, what time is it now?
[Curly grabs a clock from the inside of his jacket pocket.]
CURLY: Uh, ten minutes to four.
MOE: Hmm so it is!
[Moe grabs the clock from Curly and hits Curly on the head with it. The clock breaks.]
It gains anything up to an hour a day, particularly when my six-year-old is helping me clean the car and he pushes the button to watch the hands go round really fast.
It's fine. Time is time, we get there when we get there.
I don't really care about what time I get where I'm going, I get there when I get there.
(theeheehee, I’ve got an old Land Cruiser, there's a bit of a friendly rivalry)
And carry a few spares and tools. I bet you do, too.
How long does it take you to fill your tank?
How does any of this need you to know the time right now?
I've never been "stuck in traffic", so the problem has never arisen.
The analog clock is accurate enough that I don't fuss with it other than to reset it for DST (I have no similar children).
My solution to the lack of synchronization: turn off the radio clock (which is fortunately an option).
It's now in an e-cycling waste bin somewhere, replaced by an ESP32 I/O board and Alarmo in Home Assistant, at 1/20th the cost of the original PoS alarm.