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Snowflake symbol
- Thread starter Barak
- Start date
garth_angst
Member
Candleflame
Active Member
i have had it once in north australia.... I think when it was 18 degrees. It never gets cold here so that was a big surprise. Only locked 1% of the battery and went away after 1min or so of driving.
You can't relate it directly to outside temperature, it's based on battery temperature. You might be looking at temperature in the morning while it was colder during the night. In my garage, it might be 13C on the thermostat but my battery might be at 8C because it's sitting right over the cold concrete floor.
With that said, I never took the time to verify at what bettery temp the snowflake appears.
With that said, I never took the time to verify at what bettery temp the snowflake appears.
JCtx
Member
Where does this snowflake appears? Just curious. On our long trip, it was about 40F when we left, and there was no snowflake. Or at least I didn't see it, hence my asking. I pre-heated the battery and interior before leaving, and only ran the fan in low at 68F to maintain cabin temperature, and it worked great.
Also if you click on it or open Charging screen you will see a portion of the pack "roped off" in blue.
Brock-WI
Member
"Scan My Tesla" was reporting the mid pack at 42F with the pack at about 55% and our car had the snowflake. I will keep watching it and see if at least our car has a common temps it comes on. I know I have seen the pack at 39F with no snowflake, so there must be some other temps or cell voltage and resistance it looks at as well?
JCtx
Member
Thank you very much for that. The snowflake is pretty visible, so I'd have seen it if it was there. On my other cars, the snowflake appears at around 37-39F just to let you know there can be ice on the roads. On this car is to let you know you don't have the percentage of charge shown on the screen, right? Or does that number reflect already the diminished 'frozen' part? That'd be my last question on the subject 
. In other words, on the example on post #8, does the 39% charge figure include or exclude the frozen portion of the battery? Thank you.
. In other words, on the example on post #8, does the 39% charge figure include or exclude the frozen portion of the battery? Thank you.
When you leave a solid block of metal outside, it can get colder than the outside air. That is why bridges have signs that say bridges will freeze even when the temperature is above freezing.
Exposed metal will never drop below ambient. The reason why bridges have the sign is because they're in open air and cool down more rapidly than the road way you're approaching the bridge from, and therefore it's possible to have ice accumulation on the bridge before you encounter it on the road before the bridge.
JCtx
Member
Exactly. It's the roads that are typically warmer than ambient... except bridges, for the reason stated above.
I get the other reason why people get that impression. Let's say you're outside, and the air feels kind of cold, but then you touch something metal, and feels amazingly crazy cold! I had thought that too, that the metal was colder than the air, but I learned about what's going on there in physics in school. Transfer of heat by conduction (solid materials touching) is much faster than by convection (air). And various materials also do have a coefficient of heat conduction, and that is very high for metals. So that's what's going on there--it's conducting the heat out of your skin much faster to the metal than to the air--so it feels much colder.
jrweiss98020
Tessa's Tesla
The answer lies in the 3rd method of heat transfer - radiation!
A clear black night sky is VERY cold, so enough heat can be radiated up to the sky to reduce the temperature of an appropriate surface below ambient air temp.
A clear black night sky is VERY cold, so enough heat can be radiated up to the sky to reduce the temperature of an appropriate surface below ambient air temp.
Nothing is freezing at 37 degrees. It just isn't.
Here's what frequently happens. Overnight temperatures got down to somewhere a bit below freezing, like 29 degrees or something. From having that cold air both above and below the bridge, it definitely got cooled down more and faster by that 29 degree air and got frozen. The regular part of the road with ground underneath it stays a bit more insulated and cools down slower, so it will take longer to get to freezing and might not quite get there. And in the morning, when temperatures are starting to rise to 35, 37, etc. it will take a while for that ice to finish melting off the bridge from some traffic on it.
Well, fridges are an interesting case where that could happen because of uneven temperature distribution of where that thermometer is versus where the cold air vent in the back is. I wouldn't expect that at 37, but if you're set for 34 or 35, pretty likely if something is in the back down low.
