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Unwanted Cabin Heating

JLC13

Member
Dec 16, 2020
7
0
Ewing, NJ
As we get into colder weather here in the northeast, I've discovered an unwanted aspect of keeping my (new to me) 2013 MS plugged-in in an unheated garage: it seems to want to waste electricity heating the cabin even when I haven't called for heat via the app.

I spoke to my local service center and they recommended switching from schedule charging based on departure time to starting time which I have done. However this morning at 7am, the cabin was at 51F with an outdoor temperature of 30F (the garage is probably around 40F). The car appeared to be drawing power based on the green LED at the charge door and the flashing lights on the charger even though it had notified me that charging had completed at 4:30am based on my 4:00am scheduled starting time.

Any suggestions on how to prevent the cabin from being heated at any time while the car is plugged in unless specifically turned on via the app? This is particularly important right now when I frequently go two or three days without using the car at all.

Thanks - Jeff
 

DerbyDave

Active Member
Jul 2, 2020
1,101
651
Kentucky
I notice mine is "refreshing the charge" while plugged in, but I do not have any limitations set. I think it is just keeping the batteries at a good temperature which likely will make the cabin warmer than without any heating, as there is probably some heat transfer. The wall power shuts off frequently, and seems just to be maintenance power, just like when you open the door, the wall charger supplies the electricity needed to power the interior instead of using and discharging the 12 volt battery. If you look, it is at a low power level, and isn't at a normal charging level. It is just keeping a low power level (and not using the 12 volt battery) as much when the systems are awake and are requiring power or the battery needs some heating..
 
  • Informative
Reactions: 2101Guy

cduzz

Member
Jun 6, 2019
425
523
boston ma
I've got a 2016 D; I've seen the following behavior:

Left plugged in at or above the target SOC, my car will let the battery get super cold.

In the morning, if I crank the target charge to well above the current SOC, it will run the battery heater for some amount of time and then start charging. It will also turn on the battery heater (according to the climate tab in the app) if I turn on the climate control and the car's plugged in.

But it does appear to let my battery get as cold as it is outside (down to about 25 f which is as cold as it's gotten so far).
 

serendipitous

Member
Sep 10, 2019
389
569
Maryland, USA
There is an unintended side effect of leaving Summon Standby on - it appears to keep the cabin temp above 50 degrees. Not sure if it's so that the cameras are defrosted or something just in case you ask it to come to you, or what. But I discovered this when I left my car in an airport parking lot for a week last December. That may be what you are seeing.
 
  • Informative
Reactions: 2101Guy and Rocky_H

Lasttoy

Active Member
Mar 24, 2017
1,616
852
St Augustine, Fl
My antique doesnt do any cabin heat unless I accidently leave it on when I get home. It has been in 30s. Zero cabin heat. BUT, if it's cold outside, u will have the coolant heater on and pumps running to keep battery temp at 65.
 

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fsch

Member
Sep 21, 2015
151
177
Montreal, QC
@JLC13, I also have an MS 2013 which is usually parked in our unheated garage attached to the house, and I live in Montréal, QC, so similar situation I guess. My experience is that the car is usually 10°C (so about 20°F) above the outside temperature. It's a combined effect of the garage being somewhat heated by contact with the house, the fact that the car still spends ~150W on ancillaries when parked, and if it charges, about 20% of the power is dissipated in heat as the process is not 100% efficient, and that heat is gradually transferred to the rest of the car and the environment.
 

JLC13

Member
Dec 16, 2020
7
0
Ewing, NJ
@JLC13, I also have an MS 2013 which is usually parked in our unheated garage attached to the house, and I live in Montréal, QC, so similar situation I guess. My experience is that the car is usually 10°C (so about 20°F) above the outside temperature. It's a combined effect of the garage being somewhat heated by contact with the house, the fact that the car still spends ~150W on ancillaries when parked, and if it charges, about 20% of the power is dissipated in heat as the process is not 100% efficient, and that heat is gradually transferred to the rest of the car and the environment.

Thanks fsch! While I don't have exact figures as you do, I think what you have described is now what is happening. I am certainly no longer seeing the actual heat being on now that I have the charging scheduling set up correctly.
 

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