Vampire Power *Gain*?

[camalaio]

Noticed while stopping at a nearby grocery store the other day (warm-ish day, 28C) that we "gained" 1km of range while parked. I can maybe attribute this to some rounding right on the edge of the km-to-km transition, so didn't think much of it.

However, when my wife got in the car to come home a day later, she had gained 3km sitting in a parking lot for 8h on a hot day. We have the cabin overheat protection set to No AC, so I expect it still drains some power. Certainly not gain.

Anyone else noticed this?

 

[ewoodrick]

Battery cooled down

 

[AlanSubie4Life]

Noticed while stopping at a nearby grocery store the other day (warm-ish day, 28C) that we "gained" 1km of range while parked. I can maybe attribute this to some rounding right on the edge of the km-to-km transition, so didn't think much of it.

However, when my wife got in the car to come home a day later, she had gained 3km sitting in a parking lot for 8h on a hot day. We have the cabin overheat protection set to No AC, so I expect it still drains some power. Certainly not gain.

Anyone else noticed this?

It happens due to temperature shifts. The rated range is an estimate of remaining energy and requires a lot of correction factors to make a correct estimate. And even after correction it may not be accurate. This can also happen after a long downhill, since regen miles aren't immediately added to your total (they tend to be added in 4 rated mile increments - not sure what it will do when you have km set). If you stop after a long downhill, I'm not sure when you will be credited with your rated miles you just added via regen.

Anyway, this is one of the reasons to be cautious about 3rd part app data on overall vampire drain - I'm not convinced their methodologies are set up to capture negative drains, and constantly making that kind of error will paint a slightly worse picture over time. I'm not excusing vampire drain (though it seems to be improved lately), to be clear - I'm just saying that if you're interested in data accuracy it's best to keep track of it yourself, entirely manually, or at least cross check the apps to sanity check their results. Personally I only have Stats, and as far as I can tell, it does miss information from time to time. It definitely has its benefits, but I've turned it off for now since I've noticed recently that seems to reduce vampire drain (possibly - not certain of this, would need to do more controlled experiments).

 

[Puddles]

It’s a little known benefit to the loss of the ozone layer, and some clever engineering by Tesla. Every time there’s a solar storm or flare, a properly arranged high voltage harness will have a current induced and this current is fed into the battery.

The effect is most pronounced in Georgia. Where are you from again?

 

[MaryAnning3]

It’s a little known benefit to the loss of the ozone layer, and some clever engineering by Tesla. Every time there’s a solar storm or flare, a properly arranged high voltage harness will have a current induced and this current is fed into the battery.

The effect is most pronounced in Georgia. Where are you from again?

the effect is actually bigger in BC!

 

[SlimJim]

I have not seen it on mine. It always goes down by a few miles.

 

[darth_vad3r]

Noticed while stopping at a nearby grocery store the other day (warm-ish day, 28C) that we "gained" 1km of range while parked. I can maybe attribute this to some rounding right on the edge of the km-to-km transition, so didn't think much of it.

However, when my wife got in the car to come home a day later, she had gained 3km sitting in a parking lot for 8h on a hot day. We have the cabin overheat protection set to No AC, so I expect it still drains some power. Certainly not gain.

Anyone else noticed this?

Ya, I’ve seen it go up 2km in front of my eyes instantly. Then a minute later down 1km.

Like @AlanSubie4Life said, the gauge is based on an underlying estimate by the system on how much energy (kWh) is left in the battery.

It’s like you trying to estimate how full a measuring glass is of water, from across the room, and looking at it from different angles all the time, and sometimes you can walk closer, sometimes farther away, maybe sometimes you can use binoculars . Also once in a while someone shakes the measuring glass and the water sloshes around, or some gets added, or poured out

Estimate can change on a whim

 

[Niroc]

I have noticed lately that I am not getting the standard 2-3 mile vampire drain a day while the car is sitting idle. Either the latest software release has made some tweaks reducing the drain or the calculation doesn’t start until in drive mode. Either way, there has been a definite change in the software

 

[darth_vad3r]

I have noticed lately that I am not getting the standard 2-3 mile vampire drain a day while the car is sitting idle. Either the latest software release has made some tweaks reducing the drain or the calculation doesn’t start until in drive mode. Either way, there has been a definite change in the software

Latest being 20, or 24? How lately is “lately”?

 

[darth_vad3r]

I experienced #VampireGain of 0.48 miles (as measured by the API) overnight after 12.75 hours parked last night til today.

Not bad.

 

[Niroc]

Latest being 20, or 24? How lately is “lately”?

That would be 20. 24 was very recent. 24...just like the last upgrade, there was not any “latest” (dog climate control, games, etc) that I was interested in. I am wondering if Tesla is making improvements and adjustments and just are not listed them as “upgrades”

 

[darth_vad3r]

That would be 20. 24 was very recent. 24...just like the last upgrade, there was not any “latest” (dog climate control, games, etc) that I was interested in. I am wondering if Tesla is making improvements and adjustments and just are not listed them as “upgrades”

Yes every update likely has changes in Autopilot software as well as tons of bug fixes and tiny little tweaks they don’t bother mentioning (e.g. notifications that show on-route battery conditioning is on, Bluetooth bug fixes, etc)

 

[camalaio]

It happens due to temperature shifts. The rated range is an estimate of remaining energy and requires a lot of correction factors to make a correct estimate. And even after correction it may not be accurate. This can also happen after a long downhill, since regen miles aren't immediately added to your total (they tend to be added in 4 rated mile increments - not sure what it will do when you have km set). If you stop after a long downhill, I'm not sure when you will be credited with your rated miles you just added via regen.

Anyway, this is one of the reasons to be cautious about 3rd part app data on overall vampire drain - I'm not convinced their methodologies are set up to capture negative drains, and constantly making that kind of error will paint a slightly worse picture over time. I'm not excusing vampire drain (though it seems to be improved lately), to be clear - I'm just saying that if you're interested in data accuracy it's best to keep track of it yourself, entirely manually, or at least cross check the apps to sanity check their results. Personally I only have Stats, and as far as I can tell, it does miss information from time to time. It definitely has its benefits, but I've turned it off for now since I've noticed recently that seems to reduce vampire drain (possibly - not certain of this, would need to do more controlled experiments).

Thank you for the extremely detailed post! I suppose this should have clicked for me earlier. We're not measuring something "easy" or well defined like physical matter (e.g. gas in a tank). Now thinking of it, I'm sure I've even seen similar behaviour on my smartphone at low battery levels.

Case closed, thanks everyone

 

[Silicon Desert]

Thank you for the extremely detailed post! I suppose this should have clicked for me earlier. We're not measuring something "easy" or well defined like physical matter (e.g. gas in a tank). Now thinking of it, I'm sure I've even seen similar behaviour on my smartphone at low battery levels.

Case closed, thanks everyone

yea, you hit the mail on the head. Battery monitoring is just not that granular and often people think of it more light a scale measuring a few ounces over a couple hundred pounds.
Determining battery level is not that exact of a science, yet Tesla does a decent job of getting it close enough for government work !
Depending on what battery pack you have, that "predicted" mileage change can be just under 2% variance. not a lot.

 

[darth_vad3r]

I experienced #VampireGain of 0.48 miles (as measured by the API) overnight after 12.75 hours parked last night til today.

Not bad.

Lol, my vampire drain last night was 0.48 miles, exactly the opposite of the prior night’s gain. Hmmm... I wonder if the miles only tick up or down in some multiple of 0.48mi or if that was just a coincidence. Probably just coincidence.

But anyways, two nights in a row with 2019.24 and my average vampire drain is 0.0 miles per 24 hours parked.

 

[MentalNomad]

I've seen lots of "Vampire Gain," especially in winter. It's an effect of temperature change.

I'm more aware of it because of my circumstances:

1. Where I live, I can't charge where I normally park.
2. Because I've obsessed over getting update over this past winter, I'd often check my car through the app on waking in the morning. The app would also note the current mileage.
3. Because I work from home, I would often go a day or two without driving. The car and battery could be bone-cold in the morning. But then, in the evening, I'd hop in the car to visit someone or go to dinner.

When I'd go to the car in the evening, after the car had been warming up during the daytime heat, the battery would be warmer than it was in the early morning (after the chill of the night.) I'd open my app, I'd see the morning mileage (greyed out, as the app tries to connect and get current info), and then when it refreshes as I walked to the car, I'd see the current mileage - and sometimes I'd see as much as 20 more miles available than were there in the morning. (After a particularly bad cold snap that broke that day and temperatures rose quickly.)

 

[darth_vad3r]

Lol, my vampire drain last night was 0.48 miles, exactly the opposite of the prior night’s gain. Hmmm... I wonder if the miles only tick up or down in some multiple of 0.48mi or if that was just a coincidence. Probably just coincidence.

But anyways, two nights in a row with 2019.24 and my average vampire drain is 0.0 miles per 24 hours parked.

Hey @AlanSubie4Life I may have just stumbled upon a way to directly measure the car’s Wh/dmi constant here (Wh / dashboard mile)

0.48 mi tick ... I thought hmmm, I wonder if that’s an underlying 0.1 kWh tick?

100 Wh / 0.48 mi = 208.33 Wh/mi.

There’s still some rounding error with just one tick like this, but over two separate data points that were a dozen or more miles apart I seem to be able to pin it down to closer to 209.166 Wh/mi.

Some recent data points from the API I had for range remaining: 197.45, 196.97, 112.35.


84.62 mi x 209.1667 Wh/mi = 17.6997 kWh, aka 17.7
85.10 mi x 209.1667 Wh/mi = 17.8000 kWh, aka 17.8

Found another old API range datapoint: 203.67 mi, minus 112.35 = 91.32 mi used on dashboard, multiply by presumed 209.1667 Wh/mi constant ... 19.101 kWh, aka 19.1 kWh.

I will continue to gather more data, but it seems like my car’s (SR+) constant for actual Wh used per dashboard mile is something VERY close to exactly 209.1667 Wh/mi.

Hmm, that’s 129.97 Wh/km? Hmmmm. So, I wonder if it’s 130.00 Wh/km then?
209.21 Wh/mi? That’s seems a bit more off the mark. Hah, or maybe it’s 130 x 1.609 = 209.17, and they don’t use 1.609344
Odometer at least seems to use the full precision.

Anyways. New approach. Consistent # so far.

 

[darth_vad3r]

I've seen lots of "Vampire Gain," especially in winter. It's an effect of temperature change.

I'm more aware of it because of my circumstances:

1. Where I live, I can't charge where I normally park.
2. Because I've obsessed over getting update over this past winter, I'd often check my car through the app on waking in the morning. The app would also note the current mileage.
3. Because I work from home, I would often go a day or two without driving. The car and battery could be bone-cold in the morning. But then, in the evening, I'd hop in the car to visit someone or go to dinner.

When I'd go to the car in the evening, after the car had been warming up during the daytime heat, the battery would be warmer than it was in the early morning (after the chill of the night.) I'd open my app, I'd see the morning mileage (greyed out, as the app tries to connect and get current info), and then when it refreshes as I walked to the car, I'd see the current mileage - and sometimes I'd see as much as 20 more miles available than were there in the morning. (After a particularly bad cold snap that broke that day and temperatures rose quickly.)

Some of that can be the snowflake limitation that shows part of your battery gauge as blue and some range not usable until battery temp rises.

 

[AlanSubie4Life]

Hey @AlanSubie4Life I may have just stumbled upon a way to directly measure the car’s Wh/dmi constant here (Wh / dashboard mile)

0.48 mi tick ... I thought hmmm, I wonder if that’s an underlying 0.1 kWh tick?

100 Wh / 0.48 mi = 208.33 Wh/mi.

There’s still some rounding error with just one tick like this, but over two separate data points that were a dozen or more miles apart I seem to be able to pin it down to closer to 209.166 Wh/mi.

Some recent data points from the API I had for range remaining: 197.45, 196.97, 112.35.


84.62 mi x 209.1667 Wh/mi = 17.6997 kWh, aka 17.7
85.10 mi x 209.1667 Wh/mi = 17.8000 kWh, aka 17.8

Found another old API range datapoint: 203.67 mi, minus 112.35 = 91.32 mi used on dashboard, multiply by presumed 209.1667 Wh/mi constant ... 19.101 kWh, aka 19.1 kWh.

I will continue to gather more data, but it seems like my car’s (SR+) constant for actual Wh used per dashboard mile is something VERY close to exactly 209.1667 Wh/mi.

Hmm, that’s 129.97 Wh/km? Hmmmm. So, I wonder if it’s 130.00 Wh/km then?
209.21 Wh/mi? That’s seems a bit more off the mark. Hah, or maybe it’s 130 x 1.609 = 209.17, and they don’t use 1.609344
Odometer at least seems to use the full precision.

Anyways. New approach. Consistent # so far.

Interesting. It requires access to the API though, right? Seems possible. Works out to 50.2kWh "available" being "full". (50.2kWh/240mi = 209.1667)

I didn't really follow you on this section:

"
Some recent data points from the API I had for range remaining: 197.45, 196.97, 112.35.


84.62 mi x 209.1667 Wh/mi = 17.6997 kWh, aka 17.7
85.10 mi x 209.1667 Wh/mi = 17.8000 kWh, aka 17.8"

Just wasn't sure how the first three numbers were related to the second two bold numbers. But I understand your basic observation that 0.48mi appears to be the minimum "tick" and that might correspond with 0.1kWh.

 

[darth_vad3r]

Interesting. It requires access to the API though, right? Seems possible. Works out to 50.2kWh "available" being "full". (50.2kWh/240mi = 209.1667)

I didn't really follow you on this section:

"
Some recent data points from the API I had for range remaining: 197.45, 196.97, 112.35.


84.62 mi x 209.1667 Wh/mi = 17.6997 kWh, aka 17.7
85.10 mi x 209.1667 Wh/mi = 17.8000 kWh, aka 17.8"

Just wasn't sure how the first three numbers were related to the second two bold numbers. But I understand your basic observation that 0.48mi appears to be the minimum "tick" and that might correspond with 0.1kWh.

Sorry was short on time and skipped some steps, I was sampling some different longer intervals. 197.45 - 112.35 = 85.10 mi used on the dash.

API access via tokens and curl scripts is what I’m playing with now.

My theory is the 50.2 kWh is the above dashboard zero capacity, and the difference of ~10 Wh/mi from 209.1667 Wh/mi compared to the recharge rate of ~219 Wh/mi, multiplied by range of 240 mi = 2.4 kWh below dashboard zero “expected” for a total usable capacity of ~52.6 kWh (52.56 kWh).