Are There EVs on the Market Currently Offering a Better Energy Efficiency?

[E90alex]

I believe, my Tesla Wall Connector or any charger connected to my vehicle's charging port tells me, via the Tesla App, that I purchased so many kWh of energy today or during a charging session.

That’s not relating to anything I said.

Everybody’s efficiency between what comes out of the wall and what actually goes into the battery pack will vary depending on their specific charging setup.

Therefore it’s impossible to include that in the official efficiency rating of the vehicle because it will be different for everyone.

 

[E90alex]

Not really. At 120V, 240V, or 480V, the energy purchased in kWh is not dependent on any charging equipment. In reality that is the amount of energy I'm paying for, going into my battery, but a lot less is coming out. That is why I started the thread. Furthermore, I'm supposed to accept an additional 20% reduction in the energy output of my battery in the winter time.

No. The energy you’re paying for coming out of the wall goes to power the car electronics first, then what’s left over goes into the battery. The less quickly you charge, the more energy is used from your house to keep the car electronics running. So the efficiency of how much power leaves your wall socket versus how much energy is actually put into the battery will vary depending on your charging setup.

Imagine you’re refueling an ICE vehicle at a very slow rate, equivalent to how long it takes to charge an EV so several hours. But while you’re refueling, the vehicle is running and using gas. How much gas gets pumped into your car is not going to equal the difference in volume between where you started and a full tank, because you are continuously using fuel.

 

[WyoDude]

No, and combustion engine vehicles dont account for time spent idling the car to warm it up in the cold in their MPH numbers either.

Do you mean in the generic MPG projections?

 

[HMHM]

The energy you’re paying for coming out of the wall goes to power the car electronics first, then what’s left over goes into the battery.

I'm sorry, but this does not sound convincing. Except the Sentry mode, the electronics does not consume much electricity. No doubt, my low-voltage, 12V, battery keeps the vehicle's electronics running. But, I can't imagine using 70 kWh of energy over 1,100 miles from my HV battery to keep the tiny LV battery recharged. Nevertheless, it's an integral part of any BEV's energy efficiency matrix.

 

[father_of_6]

There are posts of owners trying to charge using 120v during winter and the energy isn't enough to warm the battery up to begin accepting a charge. The 120v circuit wastes all of it's energy fighting the cold in perpetuity.

While that's an extreme scenario, the same idea is true during normal charging... a portion of the energy coming from the circuit is powering the car's electronics and the rest is going to the battery. At higher amperages that portion is a smaller percentage, so it's more efficient.

Here's an excerpt from a thread where someone goes into more detail:

It's actually much worse than the resistive losses in the wiring. It's also the fact that the car's computer runs continuously (at 150-300W) whenever the car is charging and thus, the overhead sapped by the computer increases as power level decreases. At 120V/12A (NEMA 5-15), this overhead is about 10-20%. At 240V/48A, this overhead is only about 1-3%.

Here's that thread:

Charging advice for a weekend-only car

Hi Guys, I am getting a MYP delivered next week and wanted your advice on the charger and battery percentage. I work from home, so driving the car on weekdays is unnecessary. I will use the car on weekends to take the family out and probably use about 50-60 miles per day on Saturdays and...

teslamotorsclub.com

 

[TacoGuy]

Not really. At 120V, 240V, or 480V, the energy purchased in kWh is not dependent on any charging equipment. In reality that is the amount of energy I'm paying for, going into my battery, but a lot less is coming out. That is why I started the thread. Furthermore, I'm supposed to accept an additional 20% reduction in the energy output of my battery in the winter time.

There are losses in the charging process. What energy you attempt to put in to the car during charging does not all make it in to the battery. During AC charges there are losses at the internal inverter, to make the conversion to DC before any power hits the battery. Even in DC charging there are things like battery temperature control, and BMS circuits that need to run to optimize battery charging time.

Additionally, I have read that on the charger a Tesla can consume anywhere from 200-250Watts above and beyond the charging energy.

 

[jsight]

I've noticed that a lot of people in owners groups estimate their cost based upon net consumption.

I agree that it is better to use gross. This also highlights the benefits of 240v at higher amperages, as they tend to be more efficient than 120.

Afaik, the EPA numbers include losses in charging, but I also find them useless for real cost estimation anyway.

 

[HMHM]

Data Points:
Tesla MYLR7 2023
Date Collected: May 28, 2023
Miles Driven: 1,476
Total Energy Input: 450 kWh (305 Wh/mi)
Total Energy Consumed: 355 kWh (241 Wh/mi)
Energy Efficiency: 79%

In ICE vehicles, gallons of gasoline purchased to fill an empty fuel tank is equal to the gallons used to complete the MPG range testing. However, in case of EVs, there can be a big discrepancy between energy input (purchased) and energy used. There is a possibility of a 20% or more depletion in the electric energy supply from plug to wheel . There are energy losses at charging equipment, due to battery's self-discharge, at BMS components, and at computer controlled EV systems and processes. In EV's MPGe testing protocol, the energy input is not truly represented. At the very least, for a fair comparison with other vehicles, the MPGe range calculations for an EV should be based on the energy input to bring a battery from 0% to 100% SoC before testing.

Do you think the EV manufacturers and the EPA should reconsider their methodology and come up with revised guidelines for the testing and reporting protocols?

 

[DrChaos]

I'm sorry, but this does not sound convincing. Except the Sentry mode, the electronics does not consume much electricity.

When charging the computer is on, and the HV contactor energized (as needed for charging) it could be 200W at least.

 

[HMHM]

8% Drop in Energy Efficiency!
Tesla MYLR7 2023
Current Data Points:
Date Collected: June 23, 2023
Miles Driven: 2,125 mi
Total Energy Input: 710 kWh (334 Wh/mi)
Total Energy Consumed: 505 kWh (238 Wh/mi)
Overall Energy Efficiency: 71%

My energy efficiency has gone down from 79% to 71% in about one month time. My last data log was on May 28th at the odometer reading of 1476 miles. I drove an additional 650 mi during this period. Will the overall energy efficiency keep going down?

I'm following a new charging regimen. My Charging Best Practices:

Maintaining Li-ion (NCM & NCA) Batteries - Real-world Recommendations for BEVs. The illustrated partial recharge cycle recommendations were revised recently in light of my extensive conversations with experts and long-time Tesla owners. LFP batteries should be charged to 100% at least once every week.

Do you think this drop in overall energy efficiency has anything to do with my new charging regimen?

 

[DrChaos]

8% Drop in Energy Efficiency!
Tesla MYLR7 2023
Current Data Points:
Date Collected: June 23, 2023
Miles Driven: 2,125 mi
Total Energy Input: 710 kWh (334 Wh/mi)
Total Energy Consumed: 505 kWh (238 Wh/mi)
Overall Energy Efficiency: 71%

My energy efficiency has gone down from 79% to 71% in about one month time. My last data log was on May 28th at the odometer reading of 1476 miles. I drove an additional 650 mi during this period. Will the overall energy efficiency keep going down?

I'm following a new charging regimen. My Charging Best Practices:
View attachment 950543
Maintaining Li-ion (NCM & NCA) Batteries - Real-world Recommendations for BEVs. The illustrated partial recharge cycle recommendations were revised recently in light of my extensive conversations with experts and long-time Tesla owners. LFP batteries should be charged to 100% at least once every week.

Do you think this drop in overall energy efficiency has anything to do with my new charging regimen?

How are you measuring your energy input? Do you have a dedicated meter attached to your charging EVSE?

And when you say 'energy consumed' do you mean only by driving? My guess is that the rest would be due to HVAC use. If it's hot and you have many short trips where it has to use the AC to cool down when you start the car after sitting in the heat, lots of energy will go to that instead of driving.

The optimal state of charge for battery health is to minimize long term chemical degradation, but that doesn't have to do much with efficiency, that's more usage patterns and auxiliary electricity use.

 

[mjwojtukiewicz]

Really depends how you drive. This past week it was in the high 70s, sometimes overcast. I don't accelerate fast, I coast to a stop (regen) an generally drive less than the speed limit. I've gotten as low as 146wh/mi which is 6.8 miles/kwh. Today it was higher low to mid 200s because the heat + humidity was too oppressive. Again as with gas cars, accelerate quick, drive up to red lights and apply the brakes (this I will never understand) drive 15-20mph over the speed limit and your mileage will stink. My previous car was a 2017 Prius with an unremarkable 13miles on battery I was still able to get 50 or more mpg because I drove like like I drive the Tesla

 

[HMHM]

How are you measuring your energy input? Do you have a dedicated meter attached to your charging EVSE?

And when you say 'energy consumed' do you mean only by driving?

Energy input is the reading from charging stats on the mobile App. Whereas, the energy consumption reading is from my trip stats for the past 2,125 miles. I know the efficiency of my two electric motor is high. KERS is also adding about 10% energy back into my battery. However, I'm losing energy at various points in my EV system and equipment. I lose energy in the charging system, in BMS, including thermal management system, climate control, lighting, and other accessorial equipment.

I hope in the near future we will see a BEV which will have a PV hood, trunk, and glass roof. I'm trying to figure out if there is anything out there in Tesla EV lineup or another brand which offers a better energy matrix other than model 3.

 

[HMHM]

Really depends how you drive. This past week it was in the high 70s, sometimes overcast. I don't accelerate fast, I coast to a stop (regen) an generally drive less than the speed limit. I've gotten as low as 146wh/mi which is 6.8 miles/kwh. Today it was higher low to mid 200s because the heat + humidity was too oppressive. Again as with gas cars, accelerate quick, drive up to red lights and apply the brakes (this I will never understand) drive 15-20mph over the speed limit and your mileage will stink. My previous car was a 2017 Prius with an unremarkable 13miles on battery I was still able to get 50 or more mpg because I drove like like I drive the Tesla

I agree with your points. I believe, the time has come to start standardizing parameters for an energy star type program beyond the EPA range testing and certification.

 

[E90alex]

I'm sorry, but this does not sound convincing. Except the Sentry mode, the electronics does not consume much electricity. No doubt, my low-voltage, 12V, battery keeps the vehicle's electronics running. But, I can't imagine using 70 kWh of energy over 1,100 miles from my HV battery to keep the tiny LV battery recharged. Nevertheless, it's an integral part of any BEV's energy efficiency matrix.

I guess I missed your reply from before , but yes absolutely you could have used (lost) 70+ kWh from running the electronics.

The car takes about ~300 W to run the electronics. (Some say 250, some say as high as 450).

Charging at 120V 12 amps is about 1440 W. So about ~20% of that is lost to power the electronics if figuring 300 W consumption. Meaning if you “dispensed” 350 kWh from your wall, then 70 kWh was “lost” to running the electronics and 280 kWh went into the battery.

Calculated another way, if you charged 350 kWh worth from your wall on 120V, that’s approx 243 hours worth of charging at 1.44 kW. 243 hours of running the car electronics at ~300 W yields ~72.9kW.

If you charged at 240V 32 amps (7.68 kW), that would have taken only ~45.5 hours to dispense 350 kWh. You would have only “lost” ~13.6 kW to the electronics. Or in order to charge 280 kWh worth into the battery, it would have only taken about 38 hours, not 45.5 and you would have dispensed only about 292 kWh from the wall.

So do you see how your charging setup affects the efficiency of what is dispensed from your wall and what actually makes it into the battery? Therefore it’s not possible to quote a blanket efficiency number of electricity dispensed from the wall to actual miles driven because it varies depending how fast you’re charging.

 

[DrChaos]

Energy input is the reading from charging stats on the mobile App. Whereas, the energy consumption reading is from my trip stats for the past 2,125 miles. I know the efficiency of my two electric motor is high. KERS is also adding about 10% energy back into my battery. However, I'm losing energy at various points in my EV system and equipment. I lose energy in the charging system, in BMS, including thermal management system, climate control, lighting, and other accessorial equipment.

I hope in the near future we will see a BEV which will have a PV hood, trunk, and glass roof. I'm trying to figure out if there is anything out there in Tesla EV lineup or another brand which offers a better energy matrix other than model 3.

So far the Tesla 3 is just about the most efficient EV in all parameters of any mainstream commercial EV.

 

[HMHM]

I'm not sure how Tesla is calculating the energy consumption. In my case, the two motors, the vehicle electric and electronics, climate control, battery thermal management systems, etc. all are using energy while driving.

Does the energy reading on my trip stats include all energy consumption while driving?

 

[E90alex]

Does the energy reading on my trip stats include all energy consumption while driving?

Yes. It’s counting all energy that left the HV battery.

 

[ItsNotAboutTheMoney]

Not really. At 120V, 240V, or 480V, the energy purchased in kWh is not dependent on any charging equipment. In reality that is the amount of energy I'm paying for, going into my battery, but a lot less is coming out. That is why I started the thread. Furthermore, I'm supposed to accept an additional 20% reduction in the energy output of my battery in the winter time.

That is incorrect. Charging is significiantly less efficient at lower power due to an operating overhead while charging. Lower power means more time charging means more overhead.
There can also be variable efficiency in the onboard charger.

MPGe numbers are wall-to-wheel based, tested by the manufacturer following rules defined by the EPA. To maximize reported efficiency, the post-test recharge is likely done using whatever undocumented initial state and charging method gives the highest efficiency. If you aren't using that most efficient approach, you're not going to match the numbers.

Cold temperatures also mean that the battery will operate less efficiently and the car is more likely to use additional energy to condition the battery.

 

[kpanda17]