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Battery % used vs kWh used

A-Wimoweh

Member
Nov 26, 2018
358
177
Jungle
So one day last week, I charged my S75D up to 80% at home in the morning before leaving, and when I arrived home later that night, my battery was at 31%. So almost 50% used. When I looked at the kWh it said I used during the day, it only reported 27 kWh. I know the 75D does not really get a full 75 kWh, instead something around 70. But using almost 50% of my battery that day, I would have expected the kWh used to be close to 35 or so. Is the battery % used not on a linear scale?
 

Sorabh

Member
Mar 24, 2018
91
48
Canada
The percentage is linear.
The shown KWh used are only for driving. The KWh used for heating/cooling, operating the computers, connecting to the internet, etc.etc. are not accounted for.

Although tesla says this I dont think its accurate. You can test this yourself by running your HVAC for an hour and move the car an inch. The number of Kwh used will be greater than 0 for that.
 

f205v

Member
May 12, 2018
642
742
Tessin, Switzerland
I regularly drive the same route a couple of times per week.
Recently I checked this:
1st time (6.30 AM external temp 12C) I did it with everything OFF (A/C, ventilation, heating, music, no nav, no autopilot, screen blacked out with "cleaning mode"), driving as constant as possible at 120Kmh (it's a rather long stretch of highway). Result: 45 Km of road with 171 Wh/Km
2nd time (following day, 6.30 AM external temp 11C) I did it with everything ON (A/C, ventilation on 7, heating at 24C, music on 5, nav, autopilot), driving flat at 120Kmh with autopilot (same stretch of highway). Result: 45 Km of road with 172 Wh/Km

Allowing for 1C of temp difference, I had the same exact results. Therefore my idea that only motor consumption is accounted for, and not energy consumption from other factors.
 

Sorabh

Member
Mar 24, 2018
91
48
Canada
I regularly drive the same route a couple of times per week.
Recently I checked this:
1st time (6.30 AM external temp 12C) I did it with everything OFF (A/C, ventilation, heating, music, no nav, no autopilot, screen blacked out with "cleaning mode"), driving as constant as possible at 120Kmh (it's a rather long stretch of highway). Result: 45 Km of road with 171 Wh/Km
2nd time (following day, 6.30 AM external temp 11C) I did it with everything ON (A/C, ventilation on 7, heating at 24C, music on 5, nav, autopilot), driving flat at 120Kmh with autopilot (same stretch of highway). Result: 45 Km of road with 172 Wh/Km

Allowing for 1C of temp difference, I had the same exact results. Therefore my idea that only motor consumption is accounted for, and not energy consumption from other factors.

What were the total Kwh used on your trips?

I think the issue is not efficiency but capacity.
 

David99

Active Member
Jan 31, 2014
4,850
7,021
Brea, Orange County
The percentage is linear.
The shown KWh used are only for driving. The KWh used for heating/cooling, operating the computers, connecting to the internet, etc.etc. are not accounted for.

Everything coming out of the battery will be measured and accounted for. The trip meters also count everything, except what is used while the car is in P (park).
 

dark cloud

Active Member
Apr 14, 2018
1,922
2,163
BC
Everything coming out of the battery will be measured and accounted for. The trip meters also count everything, except what is used while the car is in P (park).


I have not sat down and calculated every single Wh of energy used, I have never installed any software to do it, for the same reason I never calculated the efficiency of my last gas powered car in one short trip to work in the winter vs. summer; it is what it is. All I can do if I am concerned with using the least amount of electricity or maximizing range is buying low rolling resistance tires, making sure they are inflated properly, going easy with the right foot, doing the speed limit and using the brake as little as possible.

What I do know is after warming the cabin, and sitting in the garage for a couple of minutes before leaving, then driving as slow and efficiently as humanly possible, slowly accelerating up to 30km/h out my driveway and my street where the speed limit is 30km/h, that first piece of data on the cluster screen; that first tenth of a km shows an efficiency usually about 600 Wh/km and as high as 1000 Wh/km. In other words not very efficient. The largest portion of this (I believe) goes to warming of the battery.

I have always assumed the only way it could be that high is taking into account the energy used in park in the garage before the trip.
 

David99

Active Member
Jan 31, 2014
4,850
7,021
Brea, Orange County
I have always assumed the only way it could be that high is taking into account the energy used in park in the garage before the trip.

I have done extensive testing with Scan My Tesla hooked up to my car. When in P the trip meter doesn't count energy. When in D it will regardless of the car moving or not.
 
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