4 ms·

> Their report showed that, on average, EV batteries have 90 percent capacity after 100,000 kilometers of driving, and at 300,000 kilometers they still have 87

> Their report showed that, on average, EV batteries have 90 percent capacity after 100,000 kilometers of driving, and at 300,000 kilometers they still have 87 percent of their original kilowatts left Another example of how KWh is the wrong unit for energy storage — gets so many people confused and they don’t know the difference between storage and power.

arlcode 2y ago
To people who know me I state the "range" in days to next charge (which I can't do at home). And that seems to be quite relatable if my circumstances are known by the recipient.
- nine_k 2y ago
  But this is very dependent on the load, speed, road quality, flat vs hilly landscape, amout of traffic lights, etc.
  - zdragnar 2y ago
    Don't forget climate, which is brutal on battery usage if you live somewhere with four seasons.
  - arlcode 2y ago
    That is true and therefore only a good measure in my friends and family circles. Many of these characterstics will be shared among us (climate, roads, landscape, charging infrastructure etc). Part of it is getting their thought processes away from "peak requirements" and into the direction of "average everyday" which for me is a more important measure. I wouldn't recommend cars be advertised this way but person to person its quite useful.
- kbutler 2y ago
  Did you do that with gas cars as well? Any reason why/why not?
  - arlcode 2y ago
    I do it with EVs (and not gas cars) because many people worry about range and charging times. They also wonder whether it's practical to own one without having access to home charging. Explaining it this way conveys the "impact" to daily life better than talking strictly about numbers. Me saying "usually I charge once a week while getting groceries" is lived experience and quite relatable (I hope). I also try to be honest and not make any claims about use cases which are not mine (I'm not trying to sell something). I very seldomly do long drives > 2h so if someone does that regularly, my personal experience won't apply. Of course if people want to nerd out over kwH and kW I'm ready to do that as well but many don't care about that. Edit: Everybody knows how gas cars work. No need to explain that. But my friends and family are curious about EVs.
    - kbutler 2y ago
      Sounds reasonable - thanks for the thoughtful reply. I agree the "delta of inconvenience" is the important measure. The on-demand model we use for gas cars is inconvenient even for gas (hate stopping for gas!) but magnified by longer EV charge times. Can charge at home? super convenient & time savings. Charge at work? may be subsidized by employer, but you may have to go move the car during the day, etc. "while shopping for groceries" is an interesting "3rd space" - you're going there consistently, so if charging works on that time frame (charger space available, doesn't require you to delay after shopping or interrupt the shopping, etc.), it's a great fit.
nine_k 2y ago
Let's go full SI. One watt is one joule per second, so 1 kWh = 3.6 MJ. Model 3's battery options are from 180 MJ to 295 MJ. Looks readable, human-scale, easier to type than kWh. To compare, 1 gallon of car fuel is about 120 MJ of thermal energy content, so about 40 MJ of mechanical output energy content, if we acccount for the ICU efficiency and transmission losses.
- Panzer04 2y ago
  Except electricity is billed in kWh, everything consumes power on kw, and kWh is by far a more intuitive unit of consumption once you get past the basic of educational step of explaining 1 kw for 1 hr = 1 kWh. As an EE I much prefer kWh, though its not all that hard to add the factor 3.6 if you really want MJ
  - aaronblohowiak 2y ago
    Most people aren’t engineers and the idea of watt-hours per hour makes eyes glaze over; miles per gallon vs… watt-hours-per-mile ? Nah that is confusing too. Miles per MJ and how many MJ does the car have is nice and clean. I think you have curse of knowledge, frankly.
AnotherGoodName 2y ago
The various AI agents seem to catch this fwiw. I prompted "check the following for errors" and got an appropriate response for this; ChatGPT: The sentence has a minor issue with the term "kilowatts". Kilowatts measure power, not energy, so it should be "kilowatt-hours" (kWh) if you're referring to the energy capacity remaining in the battery. " For all the negativity of AI i keep finding examples where it's very clear "you could do a much better job with less effort if you leaned on AI a little". Journalism especially.
dreamcompiler 2y ago
> Another example of how KWh is the wrong unit for energy storage KWh (kilowatt hours) is a measure of energy, so using it to describe energy storage capacity is correct. Using KW for this is wrong.

arlcode 2y ago

To people who know me I state the "range" in days to next charge (which I can't do at home). And that seems to be quite relatable if my circumstances are known by the recipient.

nine_k 2y ago
But this is very dependent on the load, speed, road quality, flat vs hilly landscape, amout of traffic lights, etc.
- zdragnar 2y ago
  Don't forget climate, which is brutal on battery usage if you live somewhere with four seasons.
- arlcode 2y ago
  That is true and therefore only a good measure in my friends and family circles. Many of these characterstics will be shared among us (climate, roads, landscape, charging infrastructure etc). Part of it is getting their thought processes away from "peak requirements" and into the direction of "average everyday" which for me is a more important measure. I wouldn't recommend cars be advertised this way but person to person its quite useful.
kbutler 2y ago
Did you do that with gas cars as well? Any reason why/why not?
- arlcode 2y ago
  I do it with EVs (and not gas cars) because many people worry about range and charging times. They also wonder whether it's practical to own one without having access to home charging. Explaining it this way conveys the "impact" to daily life better than talking strictly about numbers. Me saying "usually I charge once a week while getting groceries" is lived experience and quite relatable (I hope). I also try to be honest and not make any claims about use cases which are not mine (I'm not trying to sell something). I very seldomly do long drives > 2h so if someone does that regularly, my personal experience won't apply. Of course if people want to nerd out over kwH and kW I'm ready to do that as well but many don't care about that. Edit: Everybody knows how gas cars work. No need to explain that. But my friends and family are curious about EVs.
  - kbutler 2y ago
    Sounds reasonable - thanks for the thoughtful reply. I agree the "delta of inconvenience" is the important measure. The on-demand model we use for gas cars is inconvenient even for gas (hate stopping for gas!) but magnified by longer EV charge times. Can charge at home? super convenient & time savings. Charge at work? may be subsidized by employer, but you may have to go move the car during the day, etc. "while shopping for groceries" is an interesting "3rd space" - you're going there consistently, so if charging works on that time frame (charger space available, doesn't require you to delay after shopping or interrupt the shopping, etc.), it's a great fit.

nine_k 2y ago

Let's go full SI. One watt is one joule per second, so 1 kWh = 3.6 MJ. Model 3's battery options are from 180 MJ to 295 MJ. Looks readable, human-scale, easier to type than kWh. To compare, 1 gallon of car fuel is about 120 MJ of thermal energy content, so about 40 MJ of mechanical output energy content, if we acccount for the ICU efficiency and transmission losses.

Panzer04 2y ago
Except electricity is billed in kWh, everything consumes power on kw, and kWh is by far a more intuitive unit of consumption once you get past the basic of educational step of explaining 1 kw for 1 hr = 1 kWh. As an EE I much prefer kWh, though its not all that hard to add the factor 3.6 if you really want MJ
- aaronblohowiak 2y ago
  Most people aren’t engineers and the idea of watt-hours per hour makes eyes glaze over; miles per gallon vs… watt-hours-per-mile ? Nah that is confusing too. Miles per MJ and how many MJ does the car have is nice and clean. I think you have curse of knowledge, frankly.

AnotherGoodName 2y ago

The various AI agents seem to catch this fwiw. I prompted "check the following for errors" and got an appropriate response for this; ChatGPT: The sentence has a minor issue with the term "kilowatts". Kilowatts measure power, not energy, so it should be "kilowatt-hours" (kWh) if you're referring to the energy capacity remaining in the battery. " For all the negativity of AI i keep finding examples where it's very clear "you could do a much better job with less effort if you leaned on AI a little". Journalism especially.

dreamcompiler 2y ago

> Another example of how KWh is the wrong unit for energy storage KWh (kilowatt hours) is a measure of energy, so using it to describe energy storage capacity is correct. Using KW for this is wrong.