How Hot a V1 Gets in a Parked Car

barry

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I know several of you have done quick checks on the temperature a V1 reaches under normal circumstances. However, I wanted to determine just how bad things can get. Saturday I instrumented an old Valentine 1 and left it in a closed vehicle parked in direct sunlight for the day. It got way hotter than I expected. By the way, the V1 was not powered up.

Testing Details
  1. Date was 7/11/2020, location central Alabama, elevation 1,000 feet and the car was parked on grass. Parking in an asphalt parking lot may have given higher temps, but I didn’t want to suffer that much.
  2. The weather was sunny with a slight haze. There was a 15 mph breeze and the ambient temperature reached a high of 91F.
  3. Vehicle was an 2014 Audi Q5, Ibis White with Pistachio Beige interior (who comes up with these names?), panoramic sunroof with shade not pulled.
  4. Detector: Old Valentine 1 Gen 1, last 4 digits in SN 0430. This is the “thick” model with lidar diode receiver below the rear horn. Hardware version 1.7. (I didn’t want to use a current model for this test.)
  5. Detector location. Mid-height on windshield in direct sunlight.
  6. Temperatures were measured in three locations:
    • Inside the V1 case. I opened the case, fed a fine-gage thermocouple through the RJ11 socket and attached it to an integrated circuit beneath the horn using Kapton tape. (See photo below.) Of course, I closed the case back up before the test.
    • Bottom center of the case. A thermocouple was attached here using Kapton tape. (See photo.)
    • Inside the car approximately 2 inches from roof but out of direct sunlight. Used to measure interior air temp in the car.

1594673525947.png


1594673572187.png


I moved the vehicle into the sun around 9:10am, placed the detector on the windhield, positioned the cabin temperature thermocouple and then closed the windows and doors. The weater stripping was flexible enough to route the thermocouple leads between the window frame and roof. The test was stopped at 15:30 due to shade from nearby trees. However, maximum temperatures had already been reached by that time.

Results and Discussion

The TC location inside the V1 case reached a max of 175F, the bottom of the case reached 171F and the air in the car near the roof reached 145F. A graph showing the temperature variations with time is included below.

1594674109685.png


The V1 maximum temperatures were significantly higher than I expected and, recall, this was for a white vehicle. Note, the interior temperature of the V1 reached a value 30F higher than the interior temperature of the car. Of course, the V1 is in “direct” sunlight (the windshield absorbs some of the solar radiation) and sees the solar radiation heat load. The V1 heat loss will be primarily due to convective cooling of the case by the 145F cabin air and infrared radiation to the surroundings. Please note, the V1 uses a case that is roughly sealed. There are no ventilation slots to promote cooling of the interior like in some other brands. Of course, even higher temps may be expected in a hotter location.

A word of caution, if you try a similar test don’t attempt to take the V1 off of the windshield barehanded when it’s this hot.

I realize there may be concerns about the accuracy of these results, so I’ve included a discussion of possible sources of error (at least those I thought of) in a section below.


Technical Stuff in case Anyone is Interested

The thermocouples used were fine-gage (30 AWG) type K. A fine gage thermocouple is best here to minimize the “heat sink” effect that can lead to false readings when thermocouple wire is used that is too thick. The thick wire can essentially conduct heat away from the junction. In addition, Special Limits of Error thermocouple wire was used that is accurate within +/- 2.0F. (More on this later.)

Temperature measurements were taken using the thermocouple input on a Fluke 189 true RMS multimeter. Assuming a stable ambient temperature within +/- 1.8F for the multimeter, the accuracy for this input is +/- 1% of the reading plus 1.8F. This accuracy limitation could lead to a temperature reading error of up to 3.5F just from the multimeter alone.

I was uncomfortable with the potential error imposed by the thermocouple accuracy limits combined with the multimeter accuracy limits so I checked the accuracy of the multimeter/thermocouple system for each of the thermocouples using a boiling water bath and an ice bath. Compensating the National Weather Service barometric pressure for altitude gave a predicted boiling point temperature of 209.9F. Of course, the temperature of an ice bath should be 32.0F.

The table below compares the correct boiling and freezing temperatures with the values obtained from the thermocouples used in the above testing. Thermocouple I = Inside the Case TC, C = Case Bottom TC, and A = Air temp in the cabin TC. All temperatures are within 1F so I’m not going to worry about thermocouple or meter inaccuracies.



Correct Temp (F)Reading from Thermocouple I (F)Reading from Thermocouple C (F)Reading from Thermocouple A (F)
209.9​
209.6​
209.1​
209.5​
32.0​
31.6​
32.0​
32.0​


Another inaccuracy can come from the cold-junction-compensation circuitry within the multimeter. For this circuit to work properly the multimeter temperature should remain fairly constant. In my case I kept the multimeter outside in the shade. When making a measurement I tried to keep the meter shaded from the sun as best I could. Even so, this effect may have led to an inaccuracy of a degree or two. All in all, I’m confident the values presented above are easily within 3F of the actual temperatures reached.
 

V1Jake

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That is some very very very detailed testing. Greatly appreciated! Thank you for taking the time to do it.


On a side note, how do you like your Q5? My fiancé is looking to get one in a few months. (2013-2014 model, if not the Q5 then a Touareg)
 

barry

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Thanks V1Jake. I tend to get a little carried away sometimes. I can do these test, but still haven't been able to figure out how to put a degree sign in a post.

Concerning the 2014 Q5, we absolutely love it. Ours is a TDI, which has been part of the VW Group "dieselgate" issue. However, it gets between 36 and 40 mpg on the highway and has 428lb.ft. of torque. What's not to like?
 

V1Jake

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Thanks V1Jake. I tend to get a little carried away sometimes. I can do these test, but still haven't been able to figure out how to put a degree sign in a post.

Concerning the 2014 Q5, we absolutely love it. Ours is a TDI, which has been part of the VW Group "dieselgate" issue. However, it gets between 36 and 40 mpg on the highway and has 428lb.ft. of torque. What's not to like?

We all get carried away so not need to worry about that ;). The sign might be due to the forum not allowing the character or not coded for it.


Ah the diesel, good stuff. We would be getting the 2.0T. I see you don't mention any negatives so that's a plus for me!
 

sdrawkcaB

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but still haven't been able to figure out how to put a degree sign in a post.

There are a few methods for typing that character.
  • PC Keyboard: [ALT] + 1 + 7 + 6
  • Apple Mac OS & Keyboard: [Option] + [Shift] + 8
  • Apple Mac OS & Keyboard: [Option] + [0] (zero)
Note: The mathematical addition symbol, brackets, and characters within the parenthesis are not intended to be typed literally.
 
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bluehemi

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This confirms what I've seen with a dashvent thermometer, it gets to over 180+ in the Mojave desert inside a car, about 120-130 if I put a sunshade up. Its been 104-120 outside lately.
 

R4D4RUS3R

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Thanks for sharing. Your car gets pretty hot inside. I have all of my windows tinted, including the windshield and on 92 degree days like today, it rarely gets over 100 sitting in the sun. 100 is hot, no doubt about it but I never see 140 inside. I have a thermometer that says in the car because I like to see how hot it gets inside.
 

sdrawkcaB

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Thanks for sharing. Your car gets pretty hot inside. I have all of my windows tinted, including the windshield and on 92 degree days like today, it rarely gets over 100 sitting in the sun. 100 is hot, no doubt about it but I never see 140 inside. I have a thermometer that says in the car because I like to see how hot it gets inside.
I agree that I like window tint too to control the temperature. The good thing though about this test is that we can use it as a control for the sake of testing. A white car, no window tint (I presume?), and in a grassy location.

@barry - Were your windows tinted or treated at all, both OEM or aftermarket?
 

InsipidMonkey

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Thanks for taking the time to do this! It's nice to have some data points to compare to.

I've been taking an IR thermometer with me now that it's getting hot, and took some measurements as well. After sitting in full sun with the windows up, my V1G2 that is mounted at the top of the windshield registers ~150 °F (measured at the bottom of the case). After driving with the A/C on for 30 mins, the case cools to ~115-120 °F.
 

barry

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There are a few methods for typing that character.
  • PC Keyboard: [ALT] + 1 + 7 + 6
  • Apple Mac OS & Keyboard: [Option] + [Shift] + 8
  • Apple Mac OS & Keyboard: [Option] + [0] (zero)
Note: The mathematical addition symbol, brackets, and characters within the parenthesis are not intended to be typed literally.

Degree to the nth°. It’s a long hold on 0 key on iOS.

Thanks sdrawkcaB and SwankPeRFection. Very much appreciated.
Post automatically merged:

I agree that I like window tint too to control the temperature. The good thing though about this test is that we can use it as a control for the sake of testing. A white car, no window tint (I presume?), and in a grassy location.

@barry - Were your windows tinted or treated at all, both OEM or aftermarket?

sdrawkcaB, Our Q5 only has the window tint that came standard from the manufacturer. Like most SUVs, the rear side windows, tailgate window and panoramic sunroof are pretty dark. However, the front side windows have very little, if any, tint. The windshield only has a standard tint strip at the top.
 
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R4D4RUS3R

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sdrawkcaB, Our Q5 only has the window tint that came standard from the manufacturer. Like most SUVs, the rear side windows, tailgate window and panoramic sunroof are pretty dark. However, the front side windows have very little, if any, tint. The windshield only has a standard tint strip at the top.
I tint over the rear glass as well because its just a colored glass. It offers no UV reduction or heat reduction. If you dont like dark, a good quality 50% or 80% can be installed that does a lot to remove UV and heat from the interior. Our Q5 has 80% on the windshield, 15% on the front two doors and 50% over factory. Gives an even look to the side and rear color without being dark while still providing about 50% heat reduction and 99% UV reduction.
 

alee

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I did some quick thermals of the V1G2 after 1.5 hrs of driving, climate set to 69 interior, 92 degrees outside, detector mounted along the roofline. With error accounted for, it probably gets to about 100 degrees at the hottest points In favorable conditions.
 

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barry

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Thanks for sharing. Your car gets pretty hot inside. I have all of my windows tinted, including the windshield and on 92 degree days like today, it rarely gets over 100 sitting in the sun. 100 is hot, no doubt about it but I never see 140 inside. I have a thermometer that says in the car because I like to see how hot it gets inside.

I tint over the rear glass as well because its just a colored glass. It offers no UV reduction or heat reduction. If you dont like dark, a good quality 50% or 80% can be installed that does a lot to remove UV and heat from the interior. Our Q5 has 80% on the windshield, 15% on the front two doors and 50% over factory. Gives an even look to the side and rear color without being dark while still providing about 50% heat reduction and 99% UV reduction.


Pretty impressive temperature reductions due to your tinting package. Roughly were are you located? I've never been a fan of the uneven appearance due to the front side windows being totally (?) clear and the rear side windows being dark. Not to take things too off topic, but was it pretty expensive to get your tinting done?
 

True2020Vision

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I first noticed a thread title that claimed the V1/V2 could get hot enough to burn you. But I dismissed it at first, because my old V1 would get very hot if it was near the dash in an un-air-conditioned car. I'd say it would burn you if you held it between your hands, right after you took it down, but you could move it around a little.

Then a week or so after I got the V2, I left it plugged in, powered off, and hanging from the visor; while the car sat in direct sun for about an hour.

I wont let that happen again. But yeah, even though the V2 unit itself was not in direct sunlight, it got hot enough to burn.
 

smokinu454

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Interesting test for sure! Window tint will help, I didn’t check my detector but I have taken temperatures on my cars dash just out of curiosity. 2013 bmw 328i black car, black interior. 5%ceramic tint on the sides and 50% on the windshield. Outside temp 90° and the car was parked on concrete all day in the direct sunlight. The dash hit a high of around 165°. No idea without tint or what the air temp inside was.
 

ALS

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I've been using windshield sun shades for almost twenty years. The difference between using one and not is always a good twenty or more degrees inside the vehicle on days above 80 degrees.

I might be overly cautious but I would never leave a $400 or now $500 radar detector on the windshield when my car is parked. When traveling the detector and the GPS get removed from their mounts placed in their respective cases, and moved to the trunk of the vehicle.

Between the temptation to a thief, and the possible damage high temperatures may have on the internal electronics over time, it's better to be safe than sorry.
 

barry

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Thanks for taking the time to do this! It's nice to have some data points to compare to.

I've been taking an IR thermometer with me now that it's getting hot, and took some measurements as well. After sitting in full sun with the windows up, my V1G2 that is mounted at the top of the windshield registers ~150 °F (measured at the bottom of the case). After driving with the A/C on for 30 mins, the case cools to ~115-120 °F.

Thanks for the info InsipidMonkey. I wouldn't be surprised if I would have obtained similar readings if I had mounted the V1 in my normal location above the RVM. Then the V1 would have been partially shaded by the roofline and also behind the windshield tint strip.
 

R4D4RUS3R

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Pretty impressive temperature reductions due to your tinting package. Roughly were are you located? I've never been a fan of the uneven appearance due to the front side windows being totally (?) clear and the rear side windows being dark. Not to take things too off topic, but was it pretty expensive to get your tinting done?
At a shop in north MS and it was about $550 to do everything with Llumar CTX. There is another few lines above in performance but of course the price goes up. The best tint with the most effective reduction would be about $1k for the whole car. Its much more performance but in balance not enough for me to spend the extra.
 

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