The Electric Vehicle Thread

[eroscott]

I remain skeptical on the air-conditioning load, as well.

Forgot to mention A/C because it is trivial by comparison to heating. It barely moves the 'needle' in range. This was true for several years driving my Chevrolet Volt and in the past few years in my Tesla. The A/C is very efficient in these cars. These aren't the old belt drive A/C compressors.

I can use seat heaters to keep the cabin temp a couple/few degrees less (That is it is still used but not as HIGH ... that's the key point). Family and passengers love the seat heaters as they warm up *very* quickly and make people comfortable.

Also a major point is that when it is warm/hot out the batteries allow more electricity out of them.

 

[eroscott]

Yes, same as with an ICE car, an EV "gas mileage" drops rapidly as you drive faster.

Of course. But we have to keep in mind there is a bigger difference in 'fuel' usage for stop and go as gas cars use a lot of fuel at lower speeds when they are out of their efficiency designed RPM range. Electric cars are a lot more consistent/even-keeled.

BTW, thanks for the graph. There are a lot of graphs and tables for the Tesla related to speed and overcoming the air drag.

Here is an example showing over 100 miles range difference between 55mph and 75mph (373 miles vs 267 miles) for the car my son drives.

So if you ever think you are cutting it close (despite projected (ie. last 30 miles) data in the car .... just slow down by 10 or even 5 mph!

 

[eroscott]

Interesting that they use heated seats and steering wheel. Presumably that's much more efficient than heating the air and blowing it around.

I provided numbers above so not 'presumably'

Steering Wheel Heater: 95 Wh
using 1 Seat Heater: 57 Wh
using 2 Seat Heaters vs 1: 133 Wh

HVAC at 74F (23C): 342 Wh

 

[Ready]

I provided numbers above so not 'presumably'

Steering Wheel Heater: 95 Wh
using 1 Seat Heater: 57 Wh
using 2 Seat Heaters vs 1: 133 Wh

HVAC at 74F (23C): 342 Wh

I understand the steering wheel and seat heater numbers. But how are they measuring HVAC?

If the inside temperature in the car is 74F it should be using virtually no energy to keep it there. If the inside temperature is 40F it’s going to be requiring a lot of heat to warm up the cabin, and presumably a lot more energy.

 

[TromboneAl]

Interesting that they use heated seats and steering wheel. Presumably that's much more efficient than heating the air and blowing it around. I'm not convinced that would be all that comfortable around here. Maybe with some heated socks I can plug in.

Quite right. Seat heating takes much less energy, but it's not as good as heating the air.

I heat the seat to 1 (out of 3) to supplement the cabin heat. I've vowed never to put it at 3, because it gets as hot and humid as a sweaty manatee very quickly, and takes a long time to cool down. Kind of like snuggling with Lena when she gets a hot flash.

 

[NW-Bound]

For A/C operation, an EV should have less demand than an ICE car. Most cars have a front engine, which operates at near boiling point for high fuel efficiency. The firewall usually does not have that much insulation.

In all cars I ever own, when the outside temperature is 70F, it may be more than 80F inside. When I turn the A/C off and set the airflow to "Vent", that 70F ambient air becomes 80F or more when it comes out the dashboard. Awful. And so, I expect an EV to not have to run the A/C as hard as an ICE car.

And by the way, I saw somewhere that the capacity of a typical car A/C is about 1 ton. A residential A/C of 1 ton capacity may draw up to 1,500W in hot weather. A car A/C is usually less efficient due to the smaller condenser and evaporator. A source says the A/C robs an ICE of about 8 HP, which is 6 kW. That's huge, and I don't know if I can believe that.

 

[eroscott]

I understand the steering wheel and seat heater numbers. But how are they measuring HVAC?

If the inside temperature in the car is 74F it should be using virtually no energy to keep it there. If the inside temperature is 40F it’s going to be requiring a lot of heat to warm up the cabin, and presumably a lot more energy.

I think the Tesla owner that I got the data from was using a tool to watch the wattage usage. They would turn on different functions to see the wattage go up and run testing turning things on/off looking for average. My guess as I haven't watched the youtube video they did for a couple years. I did my own below just for a simple test.

I bought an adapter cable for my Tesla X and with a bluetooth OBDII adapter and the right 3rd party software you can gather data. A few minutes ago I went out to my 31F degree garage and gathered the following data with my HVAC set to 70F and my seat heater set to 1 (of 3).

From the graph of Wattage used in the 'HVAC' software tab you can see it ramp up for 2.5 minutes and then settle down to a base level. BTW, how many minutes does it take a gas engine car to warm up the cabin!

I don't know what all is in that base level but I can also see spikes which would seem to correspond to a duty cycle of the seat heaters (ie. duty cycle meaning on for Y seconds then off for Z seconds). I didn't have my steering wheel heater but I believe those are on duty cycles as well.

Screen below from the 3rd party software (ScanMyTesla) that I'm using. Here is a partial of the HVAC screen and gives you a feel for the multitude of sensors and control these cars have.

 

[Ready]

I think the Tesla owner that I got the data from was using a tool to watch the wattage usage. They would turn on different functions to see the wattage go up and run testing turning things on/off looking for average. My guess as I haven't watched the youtube video they did for a couple years. I did my own below just for a simple test.

I bought an adapter cable for my Tesla X and with a bluetooth OBDII adapter and the right 3rd party software you can gather data. A few minutes ago I went out to my 31F degree garage and gathered the following data with my HVAC set to 70F and my seat heater set to 1 (of 3).

From the graph of Wattage used in the 'HVAC' software tab you can see it ramp up for 2.5 minutes and then settle down to a base level. BTW, how many minutes does it take a gas engine car to warm up the cabin!

I don't know what all is in that base level but I can also see spikes which would seem to correspond to a duty cycle of the seat heaters (ie. duty cycle meaning on for Y seconds then off for Z seconds). I didn't have my steering wheel heater but I believe those are on duty cycles as well.

Screen below from the 3rd party software (ScanMyTesla) that I'm using. Here is a partial of the HVAC screen and gives you a feel for the multitude of sensors and control these cars have.

Thanks for sharing! It’s amazing how much data we can extract from a Tesla. How did we ever get along before cars were redesigned to be computers on wheels?

 

[CaptTom]

eroscott, thanks for those very detailed graphs. This is exactly the sort of thing I was curious about.

If I'm reading this right, the HVAC system is pulling around 2,500 Watts on average, once things settle down. That's actually pretty close to what I would have guessed, given what I know about home and boat HVAC systems.

For A/C operation, an EV should have less demand than an ICE car. Most cars have a front engine, which operates at near boiling point for high fuel efficiency. The firewall usually does not have that much insulation.

In all cars I ever own, when the outside temperature is 70F, it may be more than 80F inside. When I turn the A/C off and set the airflow to "Vent", that 70F ambient air becomes 80F or more when it comes out the dashboard. Awful. And so, I expect an EV to not have to run the A/C as hard as an ICE car.

And by the way, I saw somewhere that the capacity of a typical car A/C is about 1 ton. A residential A/C of 1 ton capacity may draw up to 1,500W in hot weather. A car A/C is usually less efficient due to the smaller condenser and evaporator. A source says the A/C robs an ICE of about 8 HP, which is 6 kW. That's huge, and I don't know if I can believe that.

That seems a bit high, but not at all out of the ballpark for an air conditioner. I seem to recall numbers much higher in old (pre-mid-seventies) cars. But I don't think it's the proximity of the engine which is causing the extra cooling load in a car. I'd bet money that it's the sun shining through all the glass. I've never been in a car which would push 80F air through the vents on a 70F day. The air is moving too fast to really pick up any heat, especially if the car is moving.

As proof, I cite the ambient air displays in most ICE vehicle dashboards nowadays. Those are pretty close to actual, even though (I think) the sensor is in the engine air intake, which is physically hot to the touch. So much outside air is being sucked in that it doesn't have time to absorb much of that engine heat.

 

[gerntz]

Of course. But we have to keep in mind there is a bigger difference in 'fuel' usage for stop and go as gas cars use a lot of fuel at lower speeds when they are out of their efficiency designed RPM range. Electric cars are a lot more consistent/even-keeled.

BTW, thanks for the graph. There are a lot of graphs and tables for the Tesla related to speed and overcoming the air drag.

Here is an example showing over 100 miles range difference between 55mph and 75mph (373 miles vs 267 miles) for the car my son drives.

So if you ever think you are cutting it close (despite projected (ie. last 30 miles) data in the car .... just slow down by 10 or even 5 mph!

Using your purple highlighted car & driving at 75mph, it would take you 3.56 hr to use up the battery, 267/75. Driving same distance at 55 mph, takes you 4.85 hr. So, can you totally recharge in less than 4.85-3.56 hr = 1.27 hr such that trip time over 267 miles is shorter at 75mph?

 

[NW-Bound]

... I don't think it's the proximity of the engine which is causing the extra cooling load in a car. I'd bet money that it's the sun shining through all the glass. I've never been in a car which would push 80F air through the vents on a 70F day. The air is moving too fast to really pick up any heat, especially if the car is moving.

As proof, I cite the ambient air displays in most ICE vehicle dashboards nowadays. Those are pretty close to actual, even though (I think) the sensor is in the engine air intake, which is physically hot to the touch. So much outside air is being sucked in that it doesn't have time to absorb much of that engine heat.

Perhaps I exaggerated, but it is my usual experience that often, even when the outside ambient temperature is pleasant, I cannot use the vent and have to run the A/C.

Next time, I will try to take some measurements.

 

[aja8888]

As proof, I cite the ambient air displays in most ICE vehicle dashboards nowadays. Those are pretty close to actual, even though (I think) the sensor is in the engine air intake, which is physically hot to the touch. So much outside air is being sucked in that it doesn't have time to absorb much of that engine heat.

Last few cars I have owned,the ambient sensor was located under the front bumper cover. The sensor in the air intake is the MAF(mass air flow) sensor which is used to provide information to the ECU for fueling maps.

 

[ncbill]

I always thought that by adding heated seats/steering wheel an EV conversion of the old Grumman LLVs (which average a whopping 10 mpg) would be a worthwhile experiment.

 

[38Chevy454]

Last few cars I have owned,the ambient sensor was located under the front bumper cover. The sensor in the air intake is the MAF(mass air flow) sensor which is used to provide information to the ECU for fueling maps.

New computer controlled cars do also have intake air temp sensors. The exterioir temp display on the inside heat/air controls is usually the second sensor located under the bumper or similar protected spot where it is less affected by sun, but still gets good airflow to read ambient temps accurately.


On the older question about A/C capacities, the old GM A6 compressor, used in 50's through early 70's I heard has a 3 ton general capacity! That's enough for a whole larger house. Of course efficiency played a big role, but those systems when working good were quite good at cooling down a vehicle.

 

[eroscott]

Using your purple highlighted car & driving at 75mph, it would take you 3.56 hr to use up the battery, 267/75. Driving same distance at 55 mph, takes you 4.85 hr. So, can you totally recharge in less than 4.85-3.56 hr = 1.27 hr such that trip time over 267 miles is shorter at 75mph?

Hope this 3 part answer helps.

a) Yes, you can charge from 10%-80% in under 30 minutes. Once charging at 85-90% SOC the charging speed (kW) slows down due to chemical reaction and battery longevity reasons. True for many batteries. Note that on the latest V3 Superchargers with the Tesla Model 3 it is even faster as the start of the charge can be up to 250 kW (vs v2 Supercharger 150 kW). Aside: the V1s were over-the-air updated from the 120 kW v1 Superchargers.

b) A couple years back people were calculating the optimum charging vs driving speed on the v1 120 kW Supercharges most examples were in the low 70 MPH range. ie. driver faster gets you to the the supercharger quicker but you have to charge longer to gain back more kWhs used. I did a 5500 mile trip last summer and drove 75-80 as I have a large battery (100kWh) and the v2 Superchargers were prevalent.

c) Please keep in mind that this thread opened up with a abetterrouteplanner online tool map which showed that optimized travel can be charge from ~10% to ~60% State-of-Charge/SOC for a short amount of time. I do a mixture of that and stay longer when I eat lunch or something which makes the following supercharger stop shorter than it otherwise would have or lets me *skip* supercharger stops altogether.

 

[eroscott]

eroscott, thanks for those very detailed graphs. This is exactly the sort of thing I was curious about.

If I'm reading this right, the HVAC system is pulling around 2,500 Watts on average, once things settle down. That's actually pretty close to what I would have guessed, given what I know about home and boat HVAC systems.

You are welcome. I'm glad you appreciated it. From eye-balling the graph, I added a trending line and it appeared to be going down. I don't know where it would have settled. ie. on a trip when driving for a > 6 minute test.

 

[TromboneAl]

Here's Lena breaking in the tires:

 

[Offgrid Organic Farmer]

^^ And of course hybrids have auto shut off/start ICE while stopped for 20 years.

My hybrid can run its ICE to recharge the drive-battery, then when the drive-battery gets 80% full the ICE shuts off.

The ICE turns on /off on its own, whenever the car decides that it wants the ICE running. That could be when climbing a hill, or if I have cruise-control set over 80mph on the interstate, or when I turn on the defrost.

 

[eroscott]

Here's Lena breaking in the tires:

Just to be 100% clear. A normal out-the-factory door Tesla cannot do that (spin tires in excess) because of the software traction control and stability control.

There are a lot of videos out there in more controlled and safe environments of people doing this. My son and I went to a track in NC last summer where they were doing this. (5 min into the first video here: https://insideevs.com/news/368674/video-tesla-model-3-drifting-track-day/ )

There are a couple current of 'unauthorized' ways to do this and a BUILT-IN way (profressional driver tuned with some less restrictive controls functioning)

1a) Unhook speed sensor wire connection (resulting in a lot of error msgs) OR
1b) pulling the electronic stability program (ESP) fuse.

2) Office Track Mode on Performance Model 3s. This is a mode you enable from the car and was designed with professional race drivers testing and tweaking. Details and video here: https://www.tesla.com/blog/how-track-mode-works

3) Future: Tesla Model S (bigger than 3) Plaid -- Prototype last year on the Nürburgring track made a lot of headlines. https://www.roadandtrack.com/new-cars/future-cars/a29487651/tesla-model-s-plaid-everything-we-know/

 

[Zathras]

I am curious as to what unexpected surprises the EV owners in our group found after they had started using their EV auto for their normal daily driving.

There were some surprises.
I wound up saving about $500 annually on junk food, soda, etc as I stopped buying at gas/convenience stores.

I was late less often.

I found driving, especially in heavy traffic, much less aggravating.

Driving long hours on trips was much less tiring. I was surprised I could travel further in a day on a road trip than I could before.

Most of the other benefits I was expecting.

 

[Clone]

Driving long hours on trips was much less tiring. I was surprised I could travel further in a day on a road trip than I could before.

Do you think this is due to noise/vibration, or due to assisted driving functions? Or even improved seats/suspension?

One thing that we noticed immediately when using autosteer in our farm tractors was that it was much less taxing to drive. You could look around more, watch what the implement was doing, etc. Letting the technology keep the tractor on the correct path allowed you to not be as fatigued at the end of the job.

 

[The Cosmic Avenger]

Do you think this is due to noise/vibration, or due to assisted driving functions? Or even improved seats/suspension?

One thing that we noticed immediately when using autosteer in our farm tractors was that it was much less taxing to drive. You could look around more, watch what the implement was doing, etc. Letting the technology keep the tractor on the correct path allowed you to not be as fatigued at the end of the job.

I was wondering the same thing. Adaptive cruise control has made driving a LOT easier for me, especially in stop-and-go traffic, which used to be so much more stressful!

 

[Extra Medium]

That's certainly your opinion. It's a personal thing...my most fun car to drive was my Corvette roadster. (and I have driven a Tesla 3)

I am definitely not trying to convince anyone else of anything as subjective as what is fun; just saying I enjoy it. I’m sure a Corvette is plenty of fun!

 

[Ready]

I do find it much easier to drive my Model 3 than I did my Lexus LS. The ability to do one pedal driving and use only regenerative braking is really a game changer in how to operate a vehicle. When I have to go back to driving an ICE rental vehicle I have to retrain myself how to drive all over again as it behaves so much differently.

 

[NW-Bound]

Many of the driver assistance functions such as adaptive cruise control are extremely useful in stop-and-go traffic such as on congested freeways in major cities.

However, these features can be implemented on any vehicle, not just EVs. In fact, Waymo full-self-driving test vehicles that have been running around Phoenix for the last 2 years are built on the Chrysler Pacifica, which is a hybrid vehicle.

By the way, Waymo new test vehicles for a taxi fleet will be built on the Jaguar I-PACE which is full electric.