Are miles really the correct measurement to use for Tesla?

[Mr Jones FL]

I have always been perplexed with using miles to determine if a vehicle is reliable. In an ICE car, there are many moving parts that relate specifically to miles (transmission, rear end, bearings, etc..). However, for an engine, I never liked this. My lawnmower and boat used hours which seemed more practical. I remember my first car and me sitting in the driveway or in a parking lot with friends playing music and the engine running for hours. I know the oil was being degraded, but my mileage didn't change, so this was a bit confusing why the oil was 3000, 5000, or 10,000 miles for a change.
For the Tesla, miles seem to mainly be for the motors, wheel bearings, and tires (basically only anything that moves when you drive). Since this is an all electric vehicle, I would like to see something else. Maybe battery charges? Hours of operation?
As I read numerous posts on here, I am more impressed with the older Teslas that are still on the road and not as much with 100k/200k/300k miles. Am I just crazy?

 

[FlatSix911]

I think that mileage and charge cycles are the two key metrics for EVs... YMMV.

 

[SSonnentag]

Charge cycles would be meaningless also unless a cycle is defined as the entire capacity of the battery being charged and then discharged. As many charges are for short daily commutes. For example, a full week of driving and charging may equate to only one charge cycle.

I think the total number of kilowatt hours added to the battery divided by the battery size would be a useful metric.

 

[SageBrush]

Range

 

[birdsquared]

Range

Or more specifically the reduction (if any) of the maximum range from when it was new to now, as a more telling metric?

 

[SammichLover]

Or more specifically the reduction (if any) of the maximum range from when it was new to now, as a more telling metric?

"Current nominal full range", which underneath is actually current kWh capacity from 100-0% multiplied by a mile (or km) per Wh that is based on something approaching real use (EPA does a decent job here).

At some point "miles" sorta matter, and they definitely do for warranty at this point, as a stand-in for "are the non-drivetrain parts of the vehicle likely wearing out?" But that's pretty darn imprecise stand-in given what will likely be a wide variance in conditions the vehicles experience.

 

[FlatSix911]

Charge cycles would be meaningless also unless a cycle is defined as the entire capacity of the battery being charged and then discharged. As many charges are for short daily commutes. For example, a full week of driving and charging may equate to only one charge cycle.

I think the total number of kilowatt hours added to the battery divided by the battery size would be a useful metric.

The definition of a charge cycle... is defined as the entire capacity of the battery being charged and then discharged.

 

[holmgang]

I have always been perplexed with using miles to determine if a vehicle is reliable. In an ICE car, there are many moving parts that relate specifically to miles (transmission, rear end, bearings, etc..). However, for an engine, I never liked this. My lawnmower and boat used hours which seemed more practical. I remember my first car and me sitting in the driveway or in a parking lot with friends playing music and the engine running for hours. I know the oil was being degraded, but my mileage didn't change, so this was a bit confusing why the oil was 3000, 5000, or 10,000 miles for a change.
For the Tesla, miles seem to mainly be for the motors, wheel bearings, and tires (basically only anything that moves when you drive). Since this is an all electric vehicle, I would like to see something else. Maybe battery charges? Hours of operation?
As I read numerous posts on here, I am more impressed with the older Teslas that are still on the road and not as much with 100k/200k/300k miles. Am I just crazy?

lawnmowers, boats, and airplanes cant measure distance, hence engine hours

a car at idle is under very low load. moving a car puts a load on engine... hence accumulated distance is the best proxy for wear-inducing use.

tires are easy consumbles. not a big deal. if im shopping for a used car, i dont need to know how many miles you put on the tires. i can see the age of the tires, their tread, and determine if they need to be replaced. mileage tells me roughly how much the suspension and bushings were exposed to use, how many times you got in and out of the car, how many times your ass slid across the seat, how many times the door latches were actuated, etc etc etc. its everything.

your other point is true yes battery health is also very important to know

 

[SageBrush]

Or more specifically the reduction (if any) of the maximum range from when it was new to now, as a more telling metric?

That would be the simple measure

Although actual depreciation these days is mostly driven by tech advances. E.g. if your battery degradation is 10% but new car battery capacity increases 50% for the same price your depreciation will be considerably higher than 10%

 

[SammichLover]

That would be the simple measure

Although actual depreciation these days is mostly driven by tech advances. E.g. if your battery degradation is 10% but new car battery capacity increases 50% for the same price your depreciation will be considerably higher than 10%

Right, that's why you just go with "miles" but rather than "odometer reading, lifetime traveled" miles it is "how far can this vehicle go on a theoretical full charge" miles. This lets you better compare to different battery sized variants of roughly the same vehicle.

 

[SageBrush]

The definition of a charge cycle... is defined as the entire capacity of the battery being charged and then discharged.

That is the manufacturer testing protocol, but it does not match up well with use. E.g. a person that cycles the battery three times from 2/3 to 1/3 for a total kWh equivalent of one charge cycle can expect to have *much* less degradation of one test cycle by the manufacturer. Perhaps 1/3 - 1/5 as much.

I know this is olde news to you -- I'm just pointing out to others that kWh used or miles driven is a VERY ymmv when it comes to pack degradation. So the reasonable way to approach this is to use range drop ... but then again, as I wrote above, that is mostly a waste of time too when the question is depreciation because that is being driven by advances in battery technology.

 

[jsight]

Charge cycles would be meaningless also unless a cycle is defined as the entire capacity of the battery being charged and then discharged. As many charges are for short daily commutes. For example, a full week of driving and charging may equate to only one charge cycle.

I think the total number of kilowatt hours added to the battery divided by the battery size would be a useful metric.

Ideally it would use an algorithm similar to the one in the AccuBattery Android App. It measures both the total % charged and the wear for each charge. For example, it considers a charge from 42% to 84% to be .26 cycles, but something like 50% to 100% might be almost a full cycle. I _think_ this algorithm is perhaps a little too dramatic in terms of the difference between the two scenarios, but it is better than a straight %.

 

[dingyibvs]

EV batteries degrade primarily with 3 extremes.

1) Extreme speed of charge/discharge. Supercharging will shorten life much quicker than 48V charging, for example.

2) Extreme states of charge. Spending a lot of time with 1% or 99% charge will degrade it quicker than maintaining 60% charge.

3) Extremes of temperature. Extensive use in 120 or -20 degree weather will degrade it faster than a constant 70 degrees.

Manufacturers employ many techniques to mitigate these effects and avoid the extremes. Mileage has a pretty minimal effect.

Of course, mileage is not everything with ICE either as we all know local miles vs highway miles, etc. However, the importance of mileage is even less in EVs.

If EV manufacturers are interested, and I suspect they won't be, they can record what percentage of the time a car is spent charging/discharging under what temperature, rate of charge/discharge, state of charge, etc.

 

[SageBrush]

Ideally it would use an algorithm similar to the one in the AccuBattery Android App. It measures both the total % charged and the wear for each charge. For example, it considers a charge from 42% to 84% to be .26 cycles, but something like 50% to 100% might be almost a full cycle. I _think_ this algorithm is perhaps a little too dramatic in terms of the difference between the two scenarios, but it is better than a straight %.

I believe it for a phone battery. The Tesla battery would presumably be less due to the thermal control. IIRC the manufacturer protocol is temperature controlled

 

[lolder]

With internal combustion engines the number of on-off cycles is also important as it relates to temperature stresses. An airline engine metric is takeoff power cycles. Our electrics don't have much temperature stress. Battery capacity loss is probably the best measure.

 

[ellett]

Why do you buy a car? To go miles (or kilometres). So miles is a key metric, probably top of the list.
Range reduction would be the next in the list, since that's a measure of convenience. When range drops to the point where you can't get to your destination and have to take time out to charge, that's a big concern. But you could consider this a sub-metric of miles.