I don't mind the temp being off when i get in the car after it's been parked. All cars have that issue. What bothers me is the fact it reads 10 or 15 degrees higher than it should after driving a decent amount of time.
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If you're looking for an accurate reading of the temperature outside, pay no attention to your car's thermometer.
On a warm summer day, it usually displays a temperature significantly higher than the actual temperature, and there are several reasons why. For starters, your car does not actually have a built-in thermometer, but a thermistor.
Most commonly, the temperature is measured with a mercury thermometer. The liquid mercury inside the thermometer expands and rises to a certain value when heat is added, and contracts and falls to a lower value when heat is removed.
A thermistor, on the other hand, measures the change in electrical current as a result of heat added or removed. The problem is not with your car's thermistor itself; in fact, thermistors are typically accurate, not to mention small and cheap to make.
The real problem is where the thermistor is located on your car. Most automakers place the thermistor on the front of the car behind the grille. This location exposes the instrument's readings to re-radiated heat from the road surface.
If you've ever walked barefoot on the beach or on a blacktop on a sunny day, you likely felt the re-radiated heat directly as your feet burned on the hot surface.
Car thermistors provide a better representation of nighttime temperatures, when the heating from the sun is lost. They are also more accurate on a cloudy day for the same reason, as well as when traveling at higher speeds and not sitting in standstill traffic.
radiative heat transfer requires line of sight. it would have been trivial to just shield the thermistor. Hard to imagine this is the actual problem.
I don't have a problem with the temp reading being inaccurate when I first get into the car on a hot day. I would expect that some convective force from driving would bring the temp down to the ambient air temp that's causing the convection. That shouldn't be hard to do.
I'm also seeing very precise but +5F inaccurate readings. If this is true across all model 3s, they should just put in a -5F fudge factor in the firmware. problem solved
What reference are you using to decide it is inaccurate?
As discussed above, the temperature of the air over the road on a sunny day is often well above the temperature posted by weather services for shaded areas.
I don't mind the temp being off when i get in the car after it's been parked. All cars have that issue. What bothers me is the fact it reads 10 or 15 degrees higher than it should after driving a decent amount of time.
It's always been an issue with mine, most of the times it shows +10 degrees higher. I think the temp sensor is inside the frunk, I put a thermometer in there and it seems to be around the same. Maybe it's a design flaw.
As discussed above, the temperature of the air over the road on a sunny day is often well above the temperature posted by weather services for shaded areas.
The readings are an average around the car. AND, it is taking in the road/street level temp (which is obviously hotter than anywhere else!). So... if the street temp is 120° and the air temp is 90°, it'll give you an average reading around the car at around 105°. Also, if you are stuck in heavy traffic, the heat generated from other cars close to you will also raise the temp..
My Model 3 always displays a higher value (+ ~ 5 degrees) from actual outside temperature. For a controlled test, I have measured the temp in my closed garage at 73 F and the car displays 77 F. Outside temps are always higher as well.
Has anyone else seen this?