I should have googled it... There's a great discussion here: The 6 kWh electricity to refine gasoline would drive an electric car the same distance as a gasser?
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Vampire Drain/Loss Tracking
- Thread starter HopeToGolf
- Start date
StealthP3D
Well-Known Member
The actual number varies from refinery to refinery because some use a different balance of energy, ie. more oil, less electricity or more natural gas, less electricity. Having looked into it, I think the bottom line is around 6kWh of ENERGY per gallon of refined gasoline. To me, it makes little difference if that energy is electricity, coal, oil or natural gas because the same energy COULD be used to generate electricity if it weren't used for refining oil into gasoline.
In any case, the amount of actual electricity used in most refineries is probably around 1kWh/gallon so even that very conservative estimate makes vampire drain look pretty benign in the bigger picture. And that's ignoring all the other energy expenditures required to refine and transport oil into gasoline. There's even the electricity required to pump the gasoline from the underground tank into the car, it's a small amount but it's not inconsequential and it all adds up.
Hello, my car was outside today. i parked it at 272km (169 miles) of range left this morning, and 6:30 hours later, it is at 250km (155mi) of range left... I didn't use the app to wake the car.
It is approx -10 C (14 F) outside.
The loss was 22 km (14 miles) in 6:30 hours... It looks to me that it is an enormous loss....
what do you think?
thank you
It is approx -10 C (14 F) outside.
The loss was 22 km (14 miles) in 6:30 hours... It looks to me that it is an enormous loss....
what do you think?
thank you
jcal0820
ride the wave
That definitely sounds excessive...but I also know in seriously cold weather, the BMS works hard to keep the battery temp modulated, and other electronic functions. Would like to see how it compares with others in similar climates this time of year.
AlanSubie4Life
Efficiency Obsessed Member
First thing I would check if you have iOS is to see if your car is sleeping using the iOS widget (it’s not 100% reliable telling you, unfortunately...). If it says “Parked” then it is not sleeping, that IS pretty consistent...
Otherwise my guess is it is doing some battery conditioning (my understanding is that that is about the temperature where this starts - but I have zero experience on that).
And if it is warming the battery presumably it would not be in sleep mode, it would be “idle” (Parked). But again, no experience.
14 miles in 6.5 hours is about 500W average.
It is too big to be just a vampire drain (if you did not forget to turn off any sit heaters or defrosters). Possibly it is a mileage recalculation as temperature was very low and part of battery capacity became "unavailable".
AlanSubie4Life
Efficiency Obsessed Member
@coleAK gathered some initial data and is waiting for much colder temps to get a handle on this. However, the two datapoints we had (one is at about 13F with about 8 hours cold soak) showed less than one mile rated range impact for a 55F -> 13F temperature change. No experience with this myself, though, and it is a tricky thing, because ideally you want to charge to the approximately identical battery % and then compare the rated range at two temps. And that’s not what was done with the data quoted above. However, still interesting.
Takes a fair amount of thought and care to identify the exact dependence of battery capacity vs. temp. And I have not seen any exhaustive analysis. I assume extrapolated max rated range plateaus at some low enough temperature, because the BMS won’t allow the battery to get colder than a certain temp - but no idea; no experience.
Well, because BMS won't allow the battery to get colder than a certain temperature does actually mean spending some energy to heat the battery. So, it would help to protect the battery, but not the range left.
AlanSubie4Life
Efficiency Obsessed Member
For sure! Looks like it could be a few hundred watts. It’s a vampire/phantom issue, but one which actually probably is necessary. And not an issue typically for people in more southerly latitudes. Would definitely be nice to know what temperature BMS seems to kick on.
So today it is 4F and 34% =105 miles. Every time I have checked it has been spot on for the 100% = 310 miles. I’ll keep you all posted when it gets < -10 -20
Also for the drain, the most I have seen is 6% (19 miles) loss in 11 hours at temps < 5F and including a 10 min pre heat to 67 degrees.
Also for the drain, the most I have seen is 6% (19 miles) loss in 11 hours at temps < 5F and including a 10 min pre heat to 67 degrees.
AlanSubie4Life
Efficiency Obsessed Member
Interesting. I assume the % values changed as well (you might not have checked). So I guess the 100% rated range does not change with temp, but the %/miles remaining DO change, depending on ambient temp. I assume this means that a 100% charged battery will go to something like 98%, if you make it very cold. Then back to 100% when warmed (neglecting vampire/phantom losses).
The calculation used by the battery gauge should always say 100%=310 miles, unless battery degradation occurs. Temperature, HVAC usage, battery conditioning, driving aggressiveness, etc do not impact that calculation. It's a straight calculation based on the max usable capacity of the battery and percentage charge.
That's also why the mileage shown by the battery gauge is virtually useless. The predicted range shown in the energy graph is the useful number since it takes the recent actual wh/mi into consideration.
I agree. I have had the battery set to % and use the power app to estimate a distance to empty. I just mentioned the % to mile correlation on the battery as some have mentioned it changes in the cold. Which I have not had happen.
AlanSubie4Life
Efficiency Obsessed Member
Also agreed.
Exactly. I was confused about what people meant by this "changes in the cold" aspect of the battery %/miles.
Based on the above datapoint, assuming zero vampire losses, it looks like you will see up to a couple % reduction (or maybe 5-6 miles) when you take a battery from warm to cold, with no drain from this battery. But, if you extrapolate the new % & miles to "full %" (so full miles = 100/ current % * current miles ), you'll always get about 310 (unless there has been battery degradation).
It's not particularly consequential, but it's good to know that's how it works.
Edit: not consequential but relevant to discussion because it really means vampire loss measurements should be done in the absence of significant temperature changes. Otherwise you lose miles that you’ll actually (potentially) get back. This has been mentioned before of course but now I see how it works. Temperature does not affect the max rated range.
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Of course. It happens couple times that on next day shown mileage was higher than day before (negative vampire drain), I only can relate that to temperature changes.
AlanSubie4Life
Efficiency Obsessed Member
I guess now that we're kind of settling in on this topic, we can summarize. And I have some additional questions!
1) The statistical "mode" (and nearly the mean) of Model 3 Phantom/Vampire drain appears to be about 2.4 miles/day, which is 580Wh/day (24W average load). I base this on the "Stats" app which keeps track of this amongst his user base. It can be higher or lower for any user on a particular day of course.
2) The vampire drain is dominated by the periods the car is in idle mode (denoted by "Parked" in the iOS widget). The draw in idle mode is typically about 100W and can be higher. It's not clear to me what the drain is in sleep mode, but it seems to be less than 10W.
3) Any vampire drain reports should be reported when the pack is at essentially the same temperature before/after. The available pack energy (and thus % & miles) are reduced when the temperature decreases (however, the extrapolated 100% charge rated range is NOT dependent on temperature - it is always ~310 miles for a relatively new battery in good shape, regardless of ambient temperature).
4) Vampire drain reports so far indicate that there may be higher losses when the vehicle is left in the cold, but so far we don't know whether the car actually uses more energy - most of those reports of lost miles may be due to the HV pack temperature dropping. We need more data on this from someone who has left their car outside in very very cold temperatures for multiple days - is the vampire drain really bad in those scenarios? We'd need daily logging of the current vehicle mileage remaining during the test interval to know. Then we would know how much energy BMS uses, approximately (and at what temperature it starts to operate).
5) There are definitely software bug situations where the car can get stuck in idle mode. This leads to very high vampire drain, but it's relatively easy to identify - just keep checking your iOS widget and you'll find your car is always in Park. Don't check the app itself; it wakes up the vehicle.
6) Some (but not all) 3rd-party apps make vampire/phantom drain a lot worse. It should be something to answer before using any such app. As far as I can tell I haven't had any problems with Stats, so far. I went for a while with no third-party apps and haven't noted any changes while using Stats.
7) You can identify whether the car was/is in sleep mode by listening for fan whirring, listening for clicking near the charge port, and by whether the contactors "clunk" when you get into the vehicle (if they clunk before you drive it means the car was sleeping...)
Remaining questions:
1) How deeply does Tesla allow the 12V battery (which I gather is an AGM battery) to be cycled? I assume this is the reason the car is forced to emerge from sleep mode, periodically - to recharge the 12V battery. This potentially will impact the life of these batteries.
2) When the car is left plugged in, does the car ever preferentially draw from the charger, rather than the 12V battery? As far as I can tell it doesn't (otherwise people wouldn't be seeing the HV battery get drawn down when plugged in)...
3) Why does Tesla even allow the HV battery to get drawn down when it is plugged in? My understanding is that use of a Lithium ion battery and available cycles are basically dependent on how much energy is drawn from it - not whether it is deep discharged and recharged or whatever. So why wear out the battery (even though it is a relatively small amount)? Is it for rebalancing purposes?
4) What is the car doing in idle mode? As far as I can tell, the only things which seem necessary are: replenishing the 12V battery, and downloading software updates. It also appears to be uploading data, which sometimes takes a while. Ideally, to replenish the 12V battery, the car would have a mode where it didn't have to burn 100W! What is using 100W, I wonder? I assume the computer...
I have some questions for app developers who may know more about the API @rawmean, do you know:
1) How does Tesla keep track of how much energy is used in a particular "sleep" cycle? I ask because in order to find out the drain, I figure the app has to poll the car...which moves it to idle mode? However, I am aware that TeslaFi and other apps can keep track of the drain in each cycle. Just wondering how Tesla is tracking it, and how they "account" for the drain in each mode.
2) Does the Tesla API give any indication of how much of the energy "lost" is due to the battery cooling down, vs. actual energy used? If they were somehow monitoring current draw from the 12V battery & HV battery, it seems like these two effects would be distinguishable. We know the HV battery has lower available energy when it is cold...but if the car can track how much power was actually used in an idle period, it would know that the reduced energy in the pack is partially due to cold, and partially due to drawdown.
1) The statistical "mode" (and nearly the mean) of Model 3 Phantom/Vampire drain appears to be about 2.4 miles/day, which is 580Wh/day (24W average load). I base this on the "Stats" app which keeps track of this amongst his user base. It can be higher or lower for any user on a particular day of course.
2) The vampire drain is dominated by the periods the car is in idle mode (denoted by "Parked" in the iOS widget). The draw in idle mode is typically about 100W and can be higher. It's not clear to me what the drain is in sleep mode, but it seems to be less than 10W.
3) Any vampire drain reports should be reported when the pack is at essentially the same temperature before/after. The available pack energy (and thus % & miles) are reduced when the temperature decreases (however, the extrapolated 100% charge rated range is NOT dependent on temperature - it is always ~310 miles for a relatively new battery in good shape, regardless of ambient temperature).
4) Vampire drain reports so far indicate that there may be higher losses when the vehicle is left in the cold, but so far we don't know whether the car actually uses more energy - most of those reports of lost miles may be due to the HV pack temperature dropping. We need more data on this from someone who has left their car outside in very very cold temperatures for multiple days - is the vampire drain really bad in those scenarios? We'd need daily logging of the current vehicle mileage remaining during the test interval to know. Then we would know how much energy BMS uses, approximately (and at what temperature it starts to operate).
5) There are definitely software bug situations where the car can get stuck in idle mode. This leads to very high vampire drain, but it's relatively easy to identify - just keep checking your iOS widget and you'll find your car is always in Park. Don't check the app itself; it wakes up the vehicle.
6) Some (but not all) 3rd-party apps make vampire/phantom drain a lot worse. It should be something to answer before using any such app. As far as I can tell I haven't had any problems with Stats, so far. I went for a while with no third-party apps and haven't noted any changes while using Stats.
7) You can identify whether the car was/is in sleep mode by listening for fan whirring, listening for clicking near the charge port, and by whether the contactors "clunk" when you get into the vehicle (if they clunk before you drive it means the car was sleeping...)
Remaining questions:
1) How deeply does Tesla allow the 12V battery (which I gather is an AGM battery) to be cycled? I assume this is the reason the car is forced to emerge from sleep mode, periodically - to recharge the 12V battery. This potentially will impact the life of these batteries.
2) When the car is left plugged in, does the car ever preferentially draw from the charger, rather than the 12V battery? As far as I can tell it doesn't (otherwise people wouldn't be seeing the HV battery get drawn down when plugged in)...
3) Why does Tesla even allow the HV battery to get drawn down when it is plugged in? My understanding is that use of a Lithium ion battery and available cycles are basically dependent on how much energy is drawn from it - not whether it is deep discharged and recharged or whatever. So why wear out the battery (even though it is a relatively small amount)? Is it for rebalancing purposes?
4) What is the car doing in idle mode? As far as I can tell, the only things which seem necessary are: replenishing the 12V battery, and downloading software updates. It also appears to be uploading data, which sometimes takes a while. Ideally, to replenish the 12V battery, the car would have a mode where it didn't have to burn 100W! What is using 100W, I wonder? I assume the computer...
I have some questions for app developers who may know more about the API @rawmean, do you know:
1) How does Tesla keep track of how much energy is used in a particular "sleep" cycle? I ask because in order to find out the drain, I figure the app has to poll the car...which moves it to idle mode? However, I am aware that TeslaFi and other apps can keep track of the drain in each cycle. Just wondering how Tesla is tracking it, and how they "account" for the drain in each mode.
2) Does the Tesla API give any indication of how much of the energy "lost" is due to the battery cooling down, vs. actual energy used? If they were somehow monitoring current draw from the 12V battery & HV battery, it seems like these two effects would be distinguishable. We know the HV battery has lower available energy when it is cold...but if the car can track how much power was actually used in an idle period, it would know that the reduced energy in the pack is partially due to cold, and partially due to drawdown.
Tesla does not provide any information related to energy used in a "sleep" cycle or lost energy/range. My app (Stats for Tesla) computes phantom drain by subtracting the energy and range at the beginning and end of a park session. The phantom drain rate is measured in "lost miles per hour" by dividing the lost range by the duration over which the loss has occurred. The following graph is the histogram of the phantom drain rate (produced by the Stats app). From this histogram, we can see that the phantom drain rate for most users is ~0.2mph.
Hope this help.
AlanSubie4Life
Efficiency Obsessed Member
I see. That is certainly straightforward enough. I understand TeslaFi somehow claims to track phantom drain in “sleep” periods as well. I assume that is by looking at the SoC at the end of the prior park session and the beginning of the current session? I guess I wonder how accurate that number would be - especially since presumably the HV battery state should not change (discharge) at all in sleep - it is disconnected by the contactors! In addition, I would expect a significant HV battery drain at the beginning of each park cycle, as the vehicle recharges the 12V battery. So the datapoints that TeslaFi gathers might not accurately capture the actual drain in sleep mode.
Basically just wondering about the accuracy of the partitioning of sleep/idle phantom drain data. No question about the 0.2mi/hr number - that seems to be correct and about right for me for the average. I just wonder about whether or not sleep mode actually is the sub-10W (based on TeslaFi data) drain we think, or whether that is incorrect and we can only speak definitively about the average drain...
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