Tesla Cross-Country Trip

[brianman]

Yes. Cabin heating or cooling figures into the equation, too. What it boils down to is that the optimal cross-country speed (to maximize range) creeps upward as the parasitic loads from pack and cabin heating/cooling increase.

Indeed, but "parasitic" isn't exactly the word I'd use for the driver or battery protection and comfort (climate control).

 

[stevezzzz]

Sure, I wasn't surprised that cabin heating would put a significant drain on range, but was surprised to find out that pack heating could do the same. It makes sense of course since at fairly steady speeds the motor and inverter should be relatively lightly loaded, highly efficient, and producing limited amounts of waste heat.

Right. But in my experience, normal driving at highway speed is enough to keep the pack warm in cold temperatures: it's starting out with a cold-soaked pack that costs you range, big-time. For instance, last night I drove a 90-mile round trip in sub-zero temperatures. By charging just before I headed out from my unheated garage, I avoided the "Battery is warming" message entirely. My consumption was still about 20% higher than nominal, but hey, I wasn't about to leave the heat off when it was -9º F. :biggrin:

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Indeed, but "parasitic" isn't exactly the word I'd use for the driver or battery protection and comfort (climate control).

Noted and agreed. But "Non-motion-inducing" is so stilted. :wink:

 

[scaesare]

Noted and agreed. But "Non-motion-inducing" is so stilted. :wink:

I've used "non-locomotive"... still doesn't roll off the tongue, but does save a syllable and a word.

 

[Cottonwood]

Right. But in my experience, normal driving at highway speed is enough to keep the pack warm in cold temperatures: it's starting out with a cold-soaked pack that costs you range, big-time. For instance, last night I drove a 90-mile round trip in sub-zero temperatures. By charging just before I headed out from my unheated garage, I avoided the "Battery is warming" message entirely. My consumption was still about 20% higher than nominal, but hey, I wasn't about to leave the heat off when it was -9º F. :biggrin:

Yes, and a significant by-product of preheating the cabin (turn on climate control with the app) is that it also warms the battery. Even in a 50˚F. garage, I have found that doing 2-4 preheat cycles (1-2 hours, turn back on every 30 minutes) is what it takes to fully warm the battery pack for long distance winter driving. This all applies to preheating on shore power.

 

[J in MN]

Even in a 50˚F. garage, I have found that doing 2-4 preheat cycles (1-2 hours, turn back on every 30 minutes) is what it takes to fully warm the battery pack for long distance winter driving. This all applies to preheating on shore power.

Can you be more precise?

My experience is that heating the cabin with range mode off, either on- or off shore power, will only heat the battery to the point where regen is zero, but without the regen disabled message (presumably zero degrees Celsius).

In a 50 degF garage there is not much if any battery warming required.

And, to stevezzzz's question, at -30 degC and < 90 km/h, the motor and inverter cannot even keep themselves warm, let alone the battery. Even at -20 degC and 100 km/h it takes more than 30 minutes to go from zero regen to 30 kW regen.

 

[stevezzzz]

Can you be more precise?

My experience is that heating the cabin with range mode off, either on- or off shore power, will only heat the battery to the point where regen is zero, but without the regen disabled message (presumably zero degrees Celsius).

In a 50 degF garage there is not much if any battery warming required.

And, to stevezzzz's question, at -30 degC and < 90 km/h, the motor and inverter cannot even keep themselves warm, let alone the battery. Even at -20 degC and 100 km/h it takes more than 30 minutes to go from zero regen to 30 kW regen.

My comments concerned only the "Battery heating" message; I had only partial regen during most of the drive. The other thing to remember is that with all that thermal mass, a warm battery will stay above ambient for a very long time. The car sat out, unplugged, in the middle of my 90 mile round trip for over three hours, in temperatures from 0º to -9º F., and I still had a little regen and no "Battery heating" warning when I started home on the last leg.

 

[Cottonwood]

Can you be more precise?

My experience is that heating the cabin with range mode off, either on- or off shore power, will only heat the battery to the point where regen is zero, but without the regen disabled message (presumably zero degrees Celsius).

In a 50 degF garage there is not much if any battery warming required.

And, to stevezzzz's question, at -30 degC and < 90 km/h, the motor and inverter cannot even keep themselves warm, let alone the battery. Even at -20 degC and 100 km/h it takes more than 30 minutes to go from zero regen to 30 kW regen.

Here is an example from a couple of months ago:

When I started with cabin temps in the low 60˚'s in a 50˚F. garage, at end of taper on a range charge, I got the power used in the curve below. This curve comes from a TED 5000 measuring power into the HPWC only. The cabin temp was set to the high 70˚'s and went to the high 80˚'s, and the air conditioner did not turn on. The lower segments of the curve below are the power drawn to do the taper on the range charge without heat. The upper, ragged segments are with the preheat on. I assume the the extra power used when the climate in "on" is power to heat the battery pack. The cabin was warm, and the air conditioner did not turn on. I further assume that the reason that the cabin went into the 80's was waste heat from the charging and battery heating. As a result of these extra shore power heat cycles, I was able to drive for 45 minutes or so in 20˚ outside temps before the cabin dropped to 65˚ with the climate control off. Also, on this trip, I noticed no extra power draw for battery heating during the drive from Paogsa to Boulder. I did stop at the 70A J1772 in Salida and the Supercharger in Silverthorne on this trip.

The big point of all of this is that (as measured by power drawn by the MS), the car will draw power for considerable periods of time (over 2 hours here) to continue heating the battery pack from shore power. I consider this to be extra energy stored in the car before a long drive in the form of thermal energy stored in the thermal mass of the interior of the car and the battery pack. Doing this preheating on shore power before a long winter drive can make a very noticeable difference in winter range.

 

[J in MN]

Here is an example from a couple of months ago:

So, did you restart the cabin heating every 20 minutes or so from the the phone app, or VisibleTesla, or something similar? Or are you saying it stayed on by itself for over 2 hours?

I have never seen the battery heater turn on when it's above freezing in my garage. In fact, based on the diagnostic screen picture, and on my own observation, it appears that the battery heater only operates below 10 deg C battery temperature.

It is known that repeatedly turning on the HVAC from the phone app will increase the cabin temperature to well above the set point. This has been discussed elsewhere on TMC before, and I am aware of another owner in Minneapolis who took his car to the service center to diagnose this "issue".

The battery heater draws 3 kW, while the cabin heater draws 0 to 4 kW in range/eco mode, and 0 to 8 kW in normal mode. The steps in your chart appear closer to 4 kW than 3 kW to my eye.

 

[Cottonwood]

So, did you restart the cabin heating every 20 minutes or so from the the phone app, or VisibleTesla, or something similar? Or are you saying it stayed on by itself for over 2 hours?

I have never seen the battery heater turn on when it's above freezing in my garage. In fact, based on the diagnostic screen picture, and on my own observation, it appears that the battery heater only operates below 10 deg C battery temperature.

It is known that repeatedly turning on the HVAC from the phone app will increase the cabin temperature to well above the set point. This has been discussed elsewhere on TMC before, and I am aware of another owner in Minneapolis who took his car to the service center to diagnose this "issue".

The battery heater draws 3 kW, while the cabin heater draws 0 to 4 kW in range/eco mode, and 0 to 8 kW in normal mode. The steps in your chart appear closer to 4 kW than 3 kW to my eye.

The power steps were about 5 kW at the beginning and dropped to 3 kW at the end. Yes, I continued to turn the "climate" on with the phone app. My assumption is that a side effect of the battery pack heating is the excess cabin heating, but that could be wrong. What I do know is that doing the charge just before I left with multiple "climate" cycles gave me an energy usage that was only slightly worse than a more moderate temperature day. I am sure that this used more energy total, but that excess was from shore power, and it did reduce the time needed to charge at the 70A J1772 to make it comfortably to the Supercharger.

 

[Doug_G]

One nit with their blog Cross Country Rally: Day One | Blog | Tesla Motors:

In an effort to keep the cars' energy use as efficient as possible, the drivers had turned off all the vehicles' extraneous features. But now was time to spend their energy profit. "Okay, we're on it," came Ford's response. "Time to rock out."

This is silly and unfortunate as it perpetuates the myth that this matters in the slightest. Driving at highway speed takes at least 20,000 watts. Playing the radio is probably going to cost you 20 watts. It'll reduce your range maybe 100 feet.

In fact, there's no reason to concern yourself with ANY electric consumption other than HVAC and drivetrain (= speed). Turn on everything you want and drop your speed 1 mph, and you'll end up ahead of the game.

 

[JRP3]

Yes, I had the exact same feeling when I read that, sends the wrong message and is completely pointless.

 

[bluetinc]

One nit with their blog Cross Country Rally: Day One | Blog | Tesla Motors:



This is silly and unfortunate as it perpetuates the myth that this matters in the slightest. Driving at highway speed takes at least 20,000 watts. Playing the radio is probably going to cost you 20 watts. It'll reduce your range maybe 100 feet.

In fact, there's no reason to concern yourself with ANY electric consumption other than HVAC and drivetrain (= speed). Turn on everything you want and drop your speed 1 mph, and you'll end up ahead of the game.

But, I think that 20W for the stereo is fairly optimistic. I think that a usage of about 100W is probably much more on target. That would mean that over a 3 hour drive, the difference is about a mile. For "us" everyday that is meaning less, but if like them you are attempting to make a record and your target arrival goal is already almost 10 miles below 0, that extra mile might count.

Peter

 

[anticitizen13.7]

Just my idle curiosity, but does anyone know the configuration of the two Model Ses used for the cross country run?

From the photos, they look like P85 w' 19" Cyclone wheels, but I wonder what other options are installed.

 

[stevezzzz]

Tesla published a new photo blog about the coast-to-coast rally on Sunday, listing every Supercharger stop with distances and charging times.

Tesla’s Cross Country Rally, Supercharger by Supercharger — Medium

 

[FANGO]

One nit with their blog Cross Country Rally: Day One | Blog | Tesla Motors:



This is silly and unfortunate as it perpetuates the myth that this matters in the slightest. Driving at highway speed takes at least 20,000 watts. Playing the radio is probably going to cost you 20 watts. It'll reduce your range maybe 100 feet.

In fact, there's no reason to concern yourself with ANY electric consumption other than HVAC and drivetrain (= speed). Turn on everything you want and drop your speed 1 mph, and you'll end up ahead of the game.

I'm getting to this late, but optimal speed is more like 20-25mph. Model S Efficiency and Range | Blog | Tesla Motors

Full breakdown of why here for roadster Roadster Efficiency and Range | Blog | Tesla Motors

You're right about the rest of course, hvac and speed are realistically the only things that matter.

 

[wycolo]

> I think that a usage of about 100W is probably much more on target. [bluetinc]

What, running subs to ward off the halt/lame/blind/crack-smoked? :smile:
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