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So how many Wh / mile are you using?
Last I checked, but no other car manufacturer has features like sentry mode, cabin preconditioning for up to 4 hours, dog mode, camp mode, super effective battery preconditioning, 3C max charge rate, etc. All of which use a lot of energy when you add it up, this is no surprise to me.. So if you want to compare, you should not be using these features when establishing a baseline... that’s my logic at least.
OP - Not sure that you got an answer to your question as the thread went a little off topic...So here are the totals for drives from 9/10/20 to 1/16/21. The 262 Wh/Mile seems pretty spot on with the rated 260 Wh/Mile by using 964 kWh over the 3685 miles driven. However, when I look at my total charging costs over that same period of time, it shows about 1347 kWh added. Where is the 383 kWh difference going? Is that all pre-heating / warming the battery? That seems like a lot of energy towards that. If I use the 1347 kWh added as "actual energy" added over that period of time, I only get 366 Wh / Mile.
It gets worse because the 1347 added assumes 100% charging efficiency. When I download the charging data and sum up the "kWh used" I get 1555 kWh (about a 87% charge efficiency. I charge at home using my Tesla Wall Connector at 13A). That drops the "actual energy" used to be over 3685 miles driven to be 422 Wh / Mile.
Is my math right? Are folks using TeslaFi seeing the same thing? Are the real world energy costs actually that much higher than the 260 Wh/Mile being advertised?
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And what are your input kWh over that same period? I’m gonna guess they’re like 1.5x
Real world numbers. I've driven 46.5 miles since charging to 90% on Sunday. I am now at 55% lol. Temperatures have been in the 20 - 36 range.
I have no monitoring apps. Did not even touch the car or app yesterday and I am an average driver. I don't accelerate fast or anything. Cabin temp I keep at 68 auto. No sentry mode.
I'd say the driving was 50% highway.
I won't charge till Saturday so we can get real numbers.
Charging on 120v or 240v? Preconditioning before departure? Using utility power?
On my i3, I see about a 20-30% reduction in range during the winter months. This applies to any EV, and the amount of range lost is directly related to how cold the outside air temp is. Also, the SoC will drop as cell temperature drops.
I am not preconditioning at all. I wanted to eliminate that variable that people claim. Preconditioning from the outlet and battery both cost money anyway. I'm not charging either that doesn't matter. When I do charge at the end of the week it will be at 240-40amps.
The point is the idea of calculating cost of real world use so it can be compared to a fuel vehicle. Not just efficiency of driven miles.
Oddly the car is still at 55% right now without being driven. I assumed it would drop more over the last 8hrs but it seems to have slowed down. Yesterday it lost 8% range.
But not preconditioning at those temperatures is skewing the numbers. This would be similar to constantly driving your ICE a short distance in cold temperatures, so that the engine never has a chance to get warm, and then wondering why you got such poor fuel economy.
In other words, your comparison should involve preconditioning on utility power since that is what the manufacturer intended when operating at those temps. After all, the manufacturer does know that doing so for merely 15 minutes will make a dramatic difference so that the heat pump isn't trying to produce heat without any help from the batteries or motors. The key is to not question the method to the madness and instead follow the manufacturer's tips/recommendations.
The more I hear about these cold temperature examples, the more it reinforces what I've been saying about the importance of using the energy before departure, rather than using even more energy after departure.
Lets assume that the 35% drop in SoC equates to 25 kWh, which was the amount of energy required to travel 47 miles in 3 days. If in ideal conditions, that 25 kWh can get you around 100 miles, that suggests to me that around 13 kWh was consumed due to inefficiencies. Lets assume that 20% of the 25 kWh was consumed due to the winter's effect on EV range, so that makes up for 5 out of the 13 kWh, leaving 8 kWh of energy unaccounted for. In my opinion, some/most of this 8 kWh of energy was wasted due to making the heat pump produce heat from practically nothing since the battery and motors were probably below freezing already. If we assume that preconditioning was used for 15 minutes before departing on each day, while plugged into your 10kW charger, that would consume a total of about 6 kWh over the course of 3 days.
So consume 6 kWh before departing to potentially save a chunk of that 13 kWh is the point I'm trying to make.
And I don't have a heat pump in my tesla.
You probably drive your ICE the way the manufacturer suggests... but you're not interested in following what Tesla suggests?
Wait.. huh? Your Tesla doesn't have a heat pump? This is the MY forum..
I totally missed that he has a P3D and not a Y. That explains the winter issue.
I don't really agree with you about preconditioning, though. That is recommended for comfort not efficiency. I've seen really high energy usage in the charger when conditioning while plugged in that would ultimately even out vs warming while driving.
This is true.I don't really agree with you about preconditioning, though. That is recommended for comfort not efficiency. I've seen really high energy usage in the charger when conditioning while plugged in that would ultimately even out vs warming while driving.
No, he's not incorrect. Let's go through that section of the manual to understand what it's talking about.I’m afraid to say that you’re incorrect regarding preconditioning being for comfort, not efficiency. It’s quite the opposite in fact, especially when dealing with sub freezing temps.
This is from the cold weather best practices section, straight out of the Tesla MY manual...
This is true.
No, he's not incorrect. Let's go through that section of the manual to understand what it's talking about.
Quote: "...and to achieve maximum range and performance, it is helpful to warm the cabin and battery before you leave"
That is talking about a tactic "to achieve maximum range", as it says. This is about if you are trying to extend the distance you can drive once you have unplugged. So it is about the practical traveling distance aspect of pre-using more of that energy from the wall so that it's not having to pull as much from the battery once it is underway, which would have reduced your driving range.
That is unrelated and actually unhelpful for the question of which way in total uses more energy. If you just take off and drive, the car obviously will only heat as much as it needs, pulling from its own battery reserves. But pre-heating from your house will usually do more than is needed, thereby wasting some extra energy on the whole.
It doesn't have to use the word "comfort". But it also doesn't use the word "efficient" or "efficiency", which is what you are claiming, does it?I have to disagree. The manual doesn't mention anything having to do with comfort in it's language when it's talking about preconditioning in cold weather.
I literally just explained that!So if not efficiency, what is it talking about when it refers to benefiting range and performance?
By getting the heat into the car before you disconnect it, the car will have more independent driving range without having to suck that extra energy from its battery later. The manual says that: "to increase maximum range".That is talking about a tactic "to achieve maximum range", as it says. This is about if you are trying to extend the distance you can drive once you have unplugged.
Because two of the three most frequent gripes from the public about electric cars are 1. range and 2. range. (The third is charging time.) Haven't you seen how many threads there are constantly across all the models of people getting worried/upset/angry and talking about class action suits from how the energy use while driving is really high and the car's total driving range while away from home is less than what they were expecting, and they were unsatisfied with that? THAT is by far what people are most concerned about. So when you ask where does it say it is "best" to do that while plugged in? That's where. It's everyone's gripes. Most people don't care as much about this nitpicking of whether it's most efficient one way or the other. What is "best" for them is being able to use the car and have enough driving range away from home, and preheating at home does increase that independent range once you unplug.Also, where does it mention that it is best to have it plugged in for best preconditioning results? The language suggests to me that, whether or not the car is plugged in, range and performance will benefit from preconditioning, due to an increase in...?
By getting the heat into the car before you disconnect it, the car will have more independent driving range without having to suck that extra energy from its battery later.
It tells us that having no regen at all does kind of hurt range because it forces always using the brake pads and is not able to recover anything when slowing down, so there is some level of warming up out of the extremely cold that helps that operation, but that doesn't extend without limit to using huge amounts of energy to get the battery really hot.I updated my previous post to clarify that it does warm the battery still when it's unplugged, which is apparently for increasing range and performance. So if it's consuming battery energy to increase range, what does that tell you?
Heh, no, generally not, or they would have said efficiency. Performance is...performance. When the battery is really cold, it will also limit power output, reducing acceleration. You know--performance. And for many people, the driving feel is an important part of how the car performs, so they don't like the partially limited regen feel.Performance is another way of saying efficiency when talking about an electrical system..