Various energy consumers demystified

[ZeeDoktor]

I've been using a BT CAN bus adapter and the tesLAX app with some custom signals I've developed to shed some light on the various subsystem's energy consumption. Here's what I've found so far:

I have a 2020 Model S Performance ("Raven"). The base energy consumption sitting in the car with gear in P and all energy consumers switched off or to minimum is 347 W. Aircon is off for all the tests.

Watts: Consumer:
38 Display at 100% brightness (instead of lowest)
79 Low beam headlights
121 Hi beams
33 Brake light
158 One seat heater level 3
125 One seat heater level 2
28 One seat heater level 1 (intermittent, switches off inbetween)
263 Rear window defog
28 Spotify play
23 Hazard lights
14 Dome lights
303 Autopilot (seems to use the same amount regardless of whether TACC+AS or only TACC is engaged).

Surprising learnings from this (for me):
- Playing music uses additional energy.
- Autosteer does not use additional energy. I would have though the servos for autosteer would consume additional energy.
- Seat heaters use interval heating, don't seem to have a permanent on position.
- lights use a lot less energy than I expected

When cruising on a highway doing 100 km/h, this translates into the following Wh/km consumption figures:
- 2 Wh/km when driving at night with high beams
- 3 Wh/km when driving with autopilot

Not that that's news, but any distance record attempts should be done during daylight hours.

 

[paulp]

Fascinating data!
Do you have consumption for when the car is asleep?

 

[ZeeDoktor]

And a couple more measurements:

Watts: Consumer:
30 front fog lights
5 rear fog lights

Then some tests to get air circulated in manual mode but with aircon/heater off:
40 blower level 1
50 blower level 2
60 blower level 3
65 blower level 4
90 blower level 5
110 blower level 6
140 blower level 7
190 blower level 8
240 blower level 11 (note that levels 9-11 automatically engage recirculation so will be of no use when not used in conjunction with aircon/heater)

Energy consumption with the car off appears variable. I switched the car off and waited 5 minutes. There are still some fans audible, and some occasional relay clicking. The resulting energy consumption fluctuates between 120 - 200W in the off state.

 

[Onshore]

Very informative. You should repost this to the main model s forum as it would be of interest to many readers.

 

[ICUDoc]

- 2 Wh/km when driving at night with high beams
- 3 Wh/km when driving with autopilot

I am surprised by this.
So if I drive, I can reduce consumption dramatically?
Seems like a crazy increase just with Autopilot.
Great posts, thankyou.
(28 watts for Spotify? There's something wrong there!!)

 

[ICUDoc]

The resulting energy consumption fluctuates between 120 - 200W in the off state.

If they can get this down then travel will be better- a five day trip to a far-flung location would use 20kWh just sitting around by those numbers- I usually assume the car will use 1kWh / day just sitting around. Your observations seem to show where Tesla should spend their time investigating a way to minimise phantom drain...

 

[ZeeDoktor]

I wouldn't say dramatically, but yes, you can certainly increase range by driving manually. aircon/heat is definitely the big drain. taking a practical drive from the other day, autopilot off vs on would have gained 7km range on a 229km drive, or about 3% difference.

 

[ZeeDoktor]

I've posted this into the main Model S forum, please respond there:

Demystifying the power consumers in my Model S

 

[ICUDoc]

i wonder how much power the RADAR uses?

 

[Candleflame]

i wonder how much power the RADAR uses?

a bit less than 300W. as per post above.

I am surprised by this.
So if I drive, I can reduce consumption dramatically?
Seems like a crazy increase just with Autopilot.
Great posts, thankyou.
(28 watts for Spotify? There's something wrong there!!)

No you cant reduce consumption dramatically.
3w / km is completely insignificant. it robs you of like 5-6km of range and this assumes you are driving 100km/h and have nothing else. The more you use the more insignificant this becomes.

28 watts for spotify sounds normal. the CPU has to work to decode and the modem has to stream via 4g.

 

[ICUDoc]

a bit less than 300W. as per post above.

No, that's how much Autopilot +/- TACC uses. Given that Spotify uses nearly 30W, I would have thought that Autopilot uses lots of power just in computation, the RADAR would be some fraction of that. My point is that there may be power savings to be found using less computer power on TACC, if Tesla were to address that.
OTOH, if RADAR uses 290W, then no point looking into decreasing TACC computer energy usage.

 

[Candleflame]

No, that's how much Autopilot +/- TACC uses. Given that Spotify uses nearly 30W, I would have thought that Autopilot uses lots of power just in computation, the RADAR would be some fraction of that. My point is that there may be power savings to be found using less computer power on TACC, if Tesla were to address that.
OTOH, if RADAR uses 290W, then no point looking into decreasing TACC computer energy usage.

the TACC activates the radar so the consumption will be included in that.

 

[rneugebauer]

I appreciate your detailed work on energy consumption, excellent and very helpful.

Can you maybe also do some research on energy used on driving (which is what I assume the car shows in kWh used or Wh per km vs energy drawn used during charging?

I suspect the consumption per km/mile is what the car takes from the battery. And that it doesn’t include a lot of the other stuff, like energy lost while not in use (vampire drain), and maybe also AC, lights or seats etc. while stopped but ‚on‘.
(I’ve never seen the Wh/km go up while waiting with lots of things on ...)

And then I guess the consumption from mains (or paid supercharger) is greater than the consumption the car shows, i.e. to have x kW available for driving I pay for a little bit more than x kW while charging.

It would be nice to know if those differences are tiny in comparison, or huge?

if the car says it has used 50 kW on a trip, how many kW does it take to bring the battery back to the original level?

 

[FEERSUMENDJIN]

Power consumption for Spotify will be amplifier driving your speakers. Try different volumes to confirm.

 

[Spacebird]

I've been using a BT CAN bus adapter and the tesLAX app with some custom signals I've developed to shed some light on the various subsystem's energy consumption. Here's what I've found so far:

I have a 2020 Model S Performance ("Raven"). The base energy consumption sitting in the car with gear in P and all energy consumers switched off or to minimum is 347 W. Aircon is off for all the tests.

Watts: Consumer:
. . . .
303 Autopilot (seems to use the same amount regardless of whether TACC+AS or only TACC is engaged).

Is TACC usage constant regardless of speed? So the faster you drive, the more efficient (w/km)?

 

[Spacebird]

Also, TACC might still save energy by maintaining a steady speed.

 

[moa999]

New Power consumption for Spotify will be amplifier driving your speakers.

Or Spotify versus radio or MP3 in stick (not sure what MCU you have)