Looking for feedback on the hypothesis that current and historical wh/mile data (if, to the degree possible, controlling for other variables) could be an indicator of overall drive-train health for EVs. All other factors being equal, will wh/mile stay generally constant over a vehicle’s life? Or will the efficiency degrade over life of vehicle?
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Does EV efficiency (as measured in wh/mi) degrade over life of EV?
- Thread starter Mosby
- Start date
ucmndd
Well-Known Member
Old thread…
As a datapoint, with 130,000 miles on my original drivetrain, the consumption reported by the car has been remarkably consistent over time.
As a datapoint, with 130,000 miles on my original drivetrain, the consumption reported by the car has been remarkably consistent over time.
Technically speaking unless friction increases, efficiency should remain constant over the life of the drivetrain. When you consider the drivetrain has an engineered estimated life of 1,000,000 miles, I think your battery pack will be replaced several times long before you have any reason to be concerned about loss of efficiency.
rexki
Member
On my old CNG car - many have said in the 300 mile club that used tires have less resistance on them that brand new tires - this would mean better performance over time due to less resistance. That is the only thing that I can think of that would change over tie that also affects miles/kWh or as Tesla newbies say Wh/mile. That is like saying gallons/mile like aircraft performance specs - not cars.
SageBrush
REJECT Fascism
I think Tesla is the only EV manufacturer in the US that uses that metric. All others use miles/kWh.
In the US, people coming from ICE cars are more comfortable with miles/energy, or mpg. I don't know why Tesla uses wH/distance unless it's what he's used to from his days in S. Africa and/or Canada (liters/100 km??).
Edit: I think Europe also uses liters/100km.
SageBrush
REJECT Fascism
That is because the others are trying to pander to American exceptionalism.
MPGe, anyone ?
Remember that a good 9/10 of Americans are confused by watts and Wh, and take it personally (if not a patriotic insult) if asked to learn.
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rexki
Member
I have had a clue for over 7 years with the electric Nissan Leaf, some are now 10 years - Tesla (non roadster drivers) are the newbies on the block.
The wH/mile is the newbie term!
SageBrush
REJECT Fascism
Mi/kWh gets messy when you have hills and regen. Normal driving of 300 Wh/mi or 3.3 kWh/mi makes sense in either units. Coast downhill where your usage hits 0 Wh/mi, and that converts to infinite mi/kWh. Go down a steeper hill at -100 Wh/mi and I understand negative energy use means charging the battery, but -10 mi/kWh sounds strange with negative distance.
Which is better -10 mi/kWh, -20 mi/kWh, or infinite mi/kWh? I bet if you asked average drivers, you’d get a bunch of confused looks and many different and mostly wrong answers. (correct answer: -10)
Which is better -10 mi/kWh, -20 mi/kWh, or infinite mi/kWh? I bet if you asked average drivers, you’d get a bunch of confused looks and many different and mostly wrong answers. (correct answer: -10)
SageBrush
REJECT Fascism
Agreed.
- It is also more straightforward to take the product of Wh/distance and distance to get energy
- Calculating averages with distance/energy units is a PITA. Most people end taking the inverses
- Our EVs tell us kWh remaining. It is straightforward to estimate range using a Wh/distance unit of measurement
TomServo
Active Member
Having owned a miles/kWh and a wh/mile car I’m not sure which I prefer and certainly neither is better.
With older cars (I’m old) before miles remaining and other computer helpers, you would reset the trip odometer every fill up. You knew your typical mileage and how many gallons you had. The sign “last fuel for x miles” sign and simple arithmetic fixed the range anxiety. It was also a good way to keep a tab on engine health (mileage drop = problem).
No such need exists in an EV, the car does better math than the driver - and teslas best in class energy graph is the bees knees.
For reference, just divide wh/mile by 1000 to get miles/kwh.
200 wh/mile = 5 miles/kwh
250 = 4
333= 3
The biggest advantage to wh/mile is it’s a large number and you can show less energy used easier than the low number miles/kwh.
The real difficulty is with “open mouth people” where a lower number is better vs higher mileage is better when running a pollution mobile.
With older cars (I’m old) before miles remaining and other computer helpers, you would reset the trip odometer every fill up. You knew your typical mileage and how many gallons you had. The sign “last fuel for x miles” sign and simple arithmetic fixed the range anxiety. It was also a good way to keep a tab on engine health (mileage drop = problem).
No such need exists in an EV, the car does better math than the driver - and teslas best in class energy graph is the bees knees.
For reference, just divide wh/mile by 1000 to get miles/kwh.
200 wh/mile = 5 miles/kwh
250 = 4
333= 3
The biggest advantage to wh/mile is it’s a large number and you can show less energy used easier than the low number miles/kwh.
The real difficulty is with “open mouth people” where a lower number is better vs higher mileage is better when running a pollution mobile.
Yes, this. People don't understand how your efficiency can go up if the number is lower.
