Inside versus Outside Temperature

Inside versus Outside Temperature

I notice the inside of my car is 20 degrees warmer than the outside temperature, even while parked overnight outdoors in New York's cold weather. The interior temperature information is reported from the iPhone app climate setting. I don't turn on the option to keep the climate control on before leaving the car. So is it normal to see this 20 degree difference? | 21/01/2020

If you have Sentry mode on, the AP processor remains on (about 250W) and the heat is directed into the cabin. That could explain the temp difference.

barrykmd | 21/01/2020

I park in a below grade parking garage where the temp is relatively constant. The car is always a few degrees warmer than ambient temp, maybe 3-5F. 20 degrees is a huge difference and I can't imagine 250 W creating enough heat for such a large difference in a winter climate.

cfishkin01 | 21/01/2020

I'm seeing about 20 as well. New York as well.

sr.smr | 22/01/2020

Thanks for the replies. I don't use sentry mode since the car is parked in a private gated driveway. With such a large difference in temperature, the car appears to unnecessarily heat the cabin and waste energy. I will schedule a visit to the service center to determine if this is normal and why.

GoldAK47 | 22/01/2020

Go find your neareast greenhouse. Check temp outside. Then check inside. Its how the world works.

If left in total darkness for long enough time, it would even out. You have no wind in car, plus electronics running. | 22/01/2020

@sr.smr - Do you see your range dropping significantly while parked? If not, the heater is not running while parked. I think @Gold hit on it. Tesla uses special thermal glass rarely found on ICE cars, which may help retain interior heat and allow for more solar heating when the sun is out.

Another thought is the outdoor temp monitor is cooled further by wind/dampness, that the inside temp monitor doesn't get. If this is really a big concern, you might get a portable temperature monitor and see what it shows for outside vs. inside. It may show a lot less than 20 degrees difference.

The temp difference is an interesting observation, but I don't see the concern or necessity for a service visit.

sr.smr | 22/01/2020

@GoldAK47, the 20 degree difference in temperature is at night. During the day, the difference is less as you predicted., I don't see a significant range reduction, so I get your point that most likely the heater is not running.
But I want to perform the temperature test as you suggested with two temperature gauges. I'll place one inside and one outside (overnight) and compare this to the readings on the iPhone Tesla app. One other fact - the car is connected to a wall charger which is programmed to start charging at midnight when the electric rates are lower. I'll take all readings at 5 am Friday at which time the car is fully charged and keep you posted with the results. | 23/01/2020

@sr - I didn't realize that you're charging. That will increase the cabin temperature, as the electronics turn on to full power, so another 100-200 watts of heating while charging is going into the cabin from the electronics. There could be some battery heat too, but that's fairly isolated so I'm doubtful that has much effect.

sr.smr | 26/01/2020, I did temperature comparisons from the app, steering wheel display, an inside and outside temperature gauge. The results were as follows: The steering wheel display and outside temperature gauge readings were nearly identical. This indicates the car's steering wheel accurately monitors outdoor temperature.

When the car is not charging, the iPhone temperature and inside temperature gauge differed by one degree.

When the car was charging, the iPhone temperature was three degrees higher than the inside temperature gauge. The car was parked in an unheated garage. Now I can't recall under what circumstances I noticed a ten degree difference.

I am monitoring the range without the car being plugged in to prove if the battery is being drained while not in use and so far the results are negligible.

So the bottom line is that I'm glad all seems to be OK and can't explain the earlier observation with the wider temperature difference.

Yodrak. | 26/01/2020

"I notice the inside of my car is 20 degrees warmer than the outside temperature"
"I can't recall under what circumstances I noticed a ten degree difference."

Can you recall what the temperature difference actually was?

sr.smr | 29/01/2020

Since I did not remember under what circumstances (charging, not charging) the wide temperature discrepancy occurred, I did tests, while charging and not charging, with independent temperature gauges placed inside and outside the car while parked at night in an unheated garage. Comparing the temperature on the steering wheel display, iPhone app, inside and outside gauges, all were very close, which is good news.

So I did a follow up test to verify the range while the car was unplugged from the wall charger over a 12 hour period in the same unheated garage with sentry mode and climate off. The outdoor temperature was 45 degrees and the range was reduced from 227 miles after a full charge to 218 miles, a loss of 9 miles on my 2017 75D. I presume the loss is normal?