Winter Range and Charging

[Rocky_H]

Like I said, other than driving at a different speed or tying kayaks on the roof, I never saw more than a ±10% deviation in fuel economy (and that was a rare thing, not dependent on weather, winter or anything else, normally within a 10% window). It is great to talk about theoretical equations, but the proof of the pudding is in the eating. There are many, many aspects of fuel economy which are not part of the air resistance equation.

Ah, this is another thing that is something to learn about the physics of this. Extra loss amounts of inefficiencies are a lot more or less noticeable, depending on how efficient the system is by default. If you have a system with really terrible efficiency, where it losing two thirds of the energy anyway and only has about a 33% efficiency, (gas engines--not exaggerating those numbers) then any extra efficiency loss amounts, like the kayaks or taking speed up to 80 mph or whatever, appear as spitting in the ocean. They are barely noticeable.

But when you have a system that by itself is 90% efficient, any extra losses you add to that look really big, because they are knocking it down to 80%, 70%, etc., and it is effectively doubling or more the loss percentages.

So this is kind of which end of the telescope or whether you are a glass half full or half empty kind of person. Gas cars suck so badly that they can't suck much worse. That's really what that is. Being blessed with an electric car that is so incredibly efficient in good conditions that any extra losses look more significant. But if you aren't aware of why there is that difference, it can seem irritating or a deficiency with the more efficient system.

 

[Fredneck]

Testing a vehicle and monitoring energy consumption while hooked up to shore power on a JuiceBox Pro 40.

Front heater is 6 kW and is variable output. Battery heater is about 5 kW (labeled as 6 kW) and is not variable output from what I can tell. More information about battery heater consumption is available in other threads - I haven't spent much time testing it.

I'm sure there is no reason to apportion the battery heater since it takes so much to warm it. They can just cycle it on and off like any other thermostat controlled heater. The cabin heater makes sense to apportion it since it sucks to blow hot then cold air.

Thanks for the info. I'll try to remember those numbers.

 

[Fredneck]

Ah, this is another thing that is something to learn about the physics of this. Extra loss amounts of inefficiencies are a lot more or less noticeable, depending on how efficient the system is by default. If you have a system with really terrible efficiency, where it losing two thirds of the energy anyway and only has about a 33% efficiency, (gas engines--not exaggerating those numbers) then any extra efficiency loss amounts, like the kayaks or taking speed up to 80 mph or whatever, appear as spitting in the ocean. They are barely noticeable.

But when you have a system that by itself is 90% efficient, any extra losses you add to that look really big, because they are knocking it down to 80%, 70%, etc., and it is effectively doubling or more the loss percentages.

So this is kind of which end of the telescope or whether you are a glass half full or half empty kind of person. Gas cars suck so badly that they can't suck much worse. That's really what that is. Being blessed with an electric car that is so incredibly efficient in good conditions that any extra losses look more significant. But if you aren't aware of why there is that difference, it can seem irritating or a deficiency with the more efficient system.

Sorry, the math you describe doesn't work that way. Loss is loss.

 

[Fredneck]

Better insulation in the doors and dash, improved HVAC design, larger ducts to the floor vents and different control algorithms.

Insulation in the doors and dash? That's like adding insulation to your house walls when the windows take up 50% of the space.

What did they do to improve the AC, or for that matter, the HV?

 

[Rocky_H]

Sorry, the math you describe doesn't work that way. Loss is loss.

You don't seem to understand the differences of "amount" versus "percentage". Yes, a loss amount is a loss amount. So let's say you have an energy loss amount from extra wind drag from a kayak strapped on a vehicle or from increased speed wind drag. Yes, a loss is a loss, because it would take the same amount of extra energy to overcome that. See? But when the gas car is wasting 5X or 10X that amount already by its default operation, versus an electric vehicle, which is losing much less than that extra wind drag amount, the % doesn't move very much in the gas car, whereas the % moves a lot from the electric car.

Make sense now, why a same loss amount would show up as a different % shift in two different types of vehicles? It's a bit like if you spilled a quart of water. That would be quite a lot lost out of a gallon jug. But that would be barely noticeable from a swimming pool. The amount is the same, but very different %.

 

[ajdelange]

Some observations (X100D - 2 row)

With the car in a cold garage with the fan at 4 and external air being admitted the heater(s) at turn on draw about 2200 W for about 1 minute. The draw then steps down over the next 5 minutes to about 1100 watts, then starts to oscillate around 1300 W. The startup transient is so brief that the average power over 30 minutes is 1300 W. In the steady state the power is PWM controlled with a baseline of about 1000 W and pulses of about 40% duty cycle with amplitude 1300W. These numbers all represent shore power and so should be reduced by 10% to reflect conversion losses. In an hour 1.3 kWh would be consumed equivalent to about 4 miles range. If I traveled at 60 mpH for this hour I would go 60 miles using about 20 kWhr with no heat but 21.3 with thus losing about 6.5% range.

Yesterday when it was 46 °F here I had to make a short trip (about 10 miles) and turned the heat on (to 71 °, fan 4) at departure. The car sat about an hour and a half and I did the same when I came home (actually I got the car out of the parking spot with the new Summon - not impressed) i.e. the heat got turned on at departure. I average about 296 Wh/mi in warm weather. These two little trips took an average of 331 so I apparently loose 11% or so with the heater on in 46 °F weather on a calm, cloudy day. in northern Virginia) I assume that outside air was being drawn in as I believe that's the default and I didn't check. The static test seems to suggest using recirculation mode shaves perhaps 25%,

Please don't try to draw global conclusions from this very particular example which suggests that the heater, in my climate, costs about 10 - 11% range. My seasonal Wh/mi records suggest that it is appreciably less than that but we do tend to use the seat heaters. In Minnesota the numbers will be different.

 

[Rocky_H]

I assume that outside air was being drawn in as I believe that's the default and I didn't check. The static test seems to suggest using recirculation mode shaves perhaps 25%,

I really recommend checking your settings and not just assuming what it's doing. I find that letting it do AUTO for the heat mode, the car decides to use recirculate, plus AIR CONDITIONING!!! It's incredibly stupid. It's using the air conditioning to dehumidify the air so that recirculate doesn't fog up the windows, but there were several threads where people were having crazy high energy draw from heat, and it was because of this. The air conditioning load is extra energy draw, plus since that chills the air, it has to heat the air even more to keep your temperature up, so that is even more energy draw. They were able to drop that energy use down by a lot by switching the A/C off and letting it use outside air, so it wasn't fighting itself by both chilling and heating the air.

 

[ajdelange]

If the air conditioner can draw heat from the cabin and transfer it to the ambient it can also draw heat from the ambient and transfer it to the cabin but I have been assured that this is not done in the X. Assured by Elon Musk? No so I can't really say but I have never seen any behaviour in the car that suggests that the A/C compressor comes on in cold weather.

I assume that the car defaults to outside air becuase every single time I turn it on it shows that and I have no reason to suspect that it would be different this time.

Finally, object was to go out the door without paying attention just as a normal user would to see if the drive I had to make would give me the huge consumption increases one often sees reported for cold weather tax. IOW answer the question new users ask frequently: "What is the cold weather tax likely to be?".

 

[Fredneck]

You don't seem to understand the differences of "amount" versus "percentage". Yes, a loss amount is a loss amount. So let's say you have an energy loss amount from extra wind drag from a kayak strapped on a vehicle or from increased speed wind drag. Yes, a loss is a loss, because it would take the same amount of extra energy to overcome that. See? But when the gas car is wasting 5X or 10X that amount already by its default operation, versus an electric vehicle, which is losing much less than that extra wind drag amount, the % doesn't move very much in the gas car, whereas the % moves a lot from the electric car.

Make sense now, why a same loss amount would show up as a different % shift in two different types of vehicles? It's a bit like if you spilled a quart of water. That would be quite a lot lost out of a gallon jug. But that would be barely noticeable from a swimming pool. The amount is the same, but very different %.

There is no way I can explain this to you so you would understand. The amount of loss the ICE has in turning gasoline into mechanical motion has zero impact on any other losses that occur after the mechanical energy has been created. Zip, none, nada.

Ask someone to explain it to you. Maybe a white board would help. It is just too painful to try to explain this sort of misunderstanding by typing over the Internet.

 

[Rocky_H]

There is no way I can explain this to you so you would understand. The amount of loss the ICE has in turning gasoline into mechanical motion has zero impact on any other losses that occur after the mechanical energy has been created. Zip, none, nada.

Ask someone to explain it to you. Maybe a white board would help. It is just too painful to try to explain this sort of misunderstanding by typing over the Internet.

It has to do with how noticeable they are. You still seem to be trying to talk about whether they exist or not. They do in both cases, but because they are a larger portion of the lost energy in an electric vehicle, they show up as more significant noticeable changes. You don't seem to be making an attempt to understand that.

You would be able to see this same effect from a lot of different kinds of extra loads. For instance, driving the air conditioning compressor is barely noticed in a change in gas mileage of a gas car, but it shows up pretty noticeably in dropping the efficiency of an EV, because it's relatively sizable compared to the small losses the car normally has.

 

[Fredneck]

It has to do with how noticeable they are. You still seem to be trying to talk about whether they exist or not. They do in both cases, but because they are a larger portion of the lost energy in an electric vehicle, they show up as more significant noticeable changes. You don't seem to be making an attempt to understand that.

You would be able to see this same effect from a lot of different kinds of extra loads. For instance, driving the air conditioning compressor is barely noticed in a change in gas mileage of a gas car, but it shows up pretty noticeably in dropping the efficiency of an EV, because it's relatively sizable compared to the small losses the car normally has.

You aren't getting it. There is no connection in any way shape or form. Look at the math, it doesn't lie. You just have to do it right.

Bottom line is that anything that happens before the ICE produces mechanical energy is water over the dam. When you calculate your mileage in an ICE, do you factor in the efficiency of the engine? No. Because all you care about is how much fuel was used. The conversion is a percentage, not a fixed loss. If the first 5 gal of each tank were lost due to some inefficiency you would be right. But the loss is relative to the energy you use, so it is part of everything, moving the car, using the headlights, running the air conditioner. So it is just part of the process and does not change the relative efficiency of moving the car vs. anything else.

Look at it this way. An EV has enormous losses in the power plant producing the electricity and then in getting that electricity to the car and still more in converting the voltages and AC to DC, and getting it into the battery. None of this factors into how much of the battery is used in keeping the cabin cool. That is directly analogous to the energy from an ICE being routed to the wheels vs. running the air conditioner.

Instead of using word games to justify what you believe, look at the math and it shall set you free!

 

[Big Earl]

Look at it this way. An EV has enormous losses in the power plant producing the electricity and then in getting that electricity to the car and still more in converting the voltages and AC to DC, and getting it into the battery. None of this factors into how much of the battery is used in keeping the cabin cool. That is directly analogous to the energy from an ICE being routed to the wheels vs. running the air conditioner.

Instead of using word games to justify what you believe, look at the math and it shall set you free!

Seems more analogous to the refinement and transportation of gasoline.

 

[Fredneck]

Seems more analogous to the refinement and transportation of gasoline.

Not sure what your point is. I'm not trying to equate the two in terms of end to end efficiency, I'm trying to explain how his math is faulty and/or he doesn't understand how to frame the problem.