4 ms·

> The issue is causing mounting concern as a number of electric-vehicle makers have warned owners not to leave the cars charging unattended in certain circumsta

> The issue is causing mounting concern as a number of electric-vehicle makers have warned owners not to leave the cars charging unattended in certain circumstances, or sitting fully charged in garages. Wow. * Don't leave your car fully charged? Stop and think about the UX there. That's a completely new paradigm: don't completely fill you car with energy? Why not just stop the charging at 90% and call that 100%? What should you leave it at? (Drone batteries should be left at 50% if not going to be used soon.) * Don't leave your car unattended while charging? So I'm supposed to sit there and watch it charge? That's sort of an unacceptable usage model, IMHO.

space_rock 5y ago
The UI is already there. Tesla doesn't charge to 100% unless you configure it for a road trip
- mdoms 5y ago
  Then something presumably isn't working right, because cars are still burning.
  - space_rock 5y ago
    I would like to know the extent of these problem and if there are other solutions. Seems this person did charge to 100%. Maybe this should be disabled for garages
- ProfessorLayton 5y ago
  I believe OP is saying that 80/90% or whatever should be displayed as 100% to the user, the same way fuel gauges in ICE vehicles typically leave a large amount of fuel in the tank while displaying as "empty". This is mainly a U.S. practice, as many European countries like their gauges to be as accurate as possible.
  - lb1lf 5y ago
    > This is mainly a U.S. practice, as many European countries like their gauges to be as accurate as possible. -Add the Japanese to that list. My Land Cruiser's low fuel lamp comes on when there's 22L/5.75 US gallons left.
    - deleted 5y ago
      [deleted]
    - benjohnson 5y ago
      That is low for an off-road vehicle where civilisation could be quite far away. My Suzuki and Chevy off-road vehicles are calibrated the same. My Buick thinks low is 24 miles of range.
      - lb1lf 5y ago
        While that's undeniably true, if venturing off-road, I'd expect the driver to plan better than simply heading back when the light comes on. (I'm probably - make that 'almost certainly' erring on the side of caution - having fitted a 90L/24USg auxiliary tank and also often carrying a jerry can or two when heading off into the boonies - heck, even my field kitchen runs on diesel!)
      - jacquesm 5y ago
        That's why you have five topped off jerrycans in the truck bed.
  - magicalhippo 5y ago
    > I believe OP is saying that 80/90% or whatever should be displayed as 100% to the user My BMW i3 does that. When my car is fully charged, it's almost exactly 80% of the actual full battery capacity. When it says it's empty it's about 20%. I verified this using some REST API calls someone had figured out reported capacity (actual and available) in kWh and correlated with the 94Ah specification.
- dzhiurgis 5y ago
  Not a Tesla user but how well it integrates with Siri? Sounds like type of thing you’d want good voice interface. Changing AC settings while driving would be great too.
  - Corrado 5y ago
    Tesla doesn't integrate with any personal assistants natively. There are 3rd party solutions (Alexa skills, etc.) available that can report on and control things ("What is the state of charge?", "Turn on the heater", etc.) Generally, I find these solutions not very user friendly at all and not well integrated. And I'm personally a bit wary about the security of it all. Giving a 3rd party access to my calendar is one thing; letting them control my car is something different.
    - dzhiurgis 5y ago
      Well it’s changing your temperature or opening window at most, not driving off a cliff
pests 5y ago
Tesla suggests only 80/%90% anyways as complete fill/drain cycles degrades the battery faster.
3pt14159 5y ago
I'm sort of perplexed that this is even a problem? Surely it's possible to dynamically disengage the charging mechanism once full?
- r1ch 5y ago
  The problem is that batteries themselves don't have a concept of "full". Measuring the state of charge in Li-ion cells is not easy as the voltage curve can be quite flat, so you have to use all kinds of heuristics to determine what a safe charge level is.
  - 3pt14159 5y ago
    I see. Thanks. I take it thermal differential between battery and outdoor air won't work for some reason?
    - r1ch 5y ago
      Batteries heat up depending on the rate of charge and while it is easy to measure and control to avoid damage from overheating, I don't believe it can be used to measure the state of charge. Charging at home in a garage would likely be using a much slower (and thus cooler) charging method than a commercial charger, so I don't think the fires are caused by the rate of charge, but perhaps by over-charging potentially worn or damaged / defective cells.
  - turtlebits 5y ago
    Are you sure that's correct? The BMS should have a high voltage disconnect and not allow further charging.
    - r1ch 5y ago
      I'm sure it does - the problem is that the disconnect trigger voltage could be a normal state of charge for one cell but a high / dangerous state of charge for another.
didntknowya 5y ago
i think most chargers (phone etc) have a "don't leave unattended while charging" warning as well just to cover their bases.

space_rock 5y ago

The UI is already there. Tesla doesn't charge to 100% unless you configure it for a road trip

mdoms 5y ago
Then something presumably isn't working right, because cars are still burning.
- space_rock 5y ago
  I would like to know the extent of these problem and if there are other solutions. Seems this person did charge to 100%. Maybe this should be disabled for garages
ProfessorLayton 5y ago
I believe OP is saying that 80/90% or whatever should be displayed as 100% to the user, the same way fuel gauges in ICE vehicles typically leave a large amount of fuel in the tank while displaying as "empty". This is mainly a U.S. practice, as many European countries like their gauges to be as accurate as possible.
- lb1lf 5y ago
  > This is mainly a U.S. practice, as many European countries like their gauges to be as accurate as possible. -Add the Japanese to that list. My Land Cruiser's low fuel lamp comes on when there's 22L/5.75 US gallons left.
  - deleted 5y ago
    [deleted]
  - benjohnson 5y ago
    That is low for an off-road vehicle where civilisation could be quite far away. My Suzuki and Chevy off-road vehicles are calibrated the same. My Buick thinks low is 24 miles of range.
    - lb1lf 5y ago
      While that's undeniably true, if venturing off-road, I'd expect the driver to plan better than simply heading back when the light comes on. (I'm probably - make that 'almost certainly' erring on the side of caution - having fitted a 90L/24USg auxiliary tank and also often carrying a jerry can or two when heading off into the boonies - heck, even my field kitchen runs on diesel!)
    - jacquesm 5y ago
      That's why you have five topped off jerrycans in the truck bed.
- magicalhippo 5y ago
  > I believe OP is saying that 80/90% or whatever should be displayed as 100% to the user My BMW i3 does that. When my car is fully charged, it's almost exactly 80% of the actual full battery capacity. When it says it's empty it's about 20%. I verified this using some REST API calls someone had figured out reported capacity (actual and available) in kWh and correlated with the 94Ah specification.
dzhiurgis 5y ago
Not a Tesla user but how well it integrates with Siri? Sounds like type of thing you’d want good voice interface. Changing AC settings while driving would be great too.
- Corrado 5y ago
  Tesla doesn't integrate with any personal assistants natively. There are 3rd party solutions (Alexa skills, etc.) available that can report on and control things ("What is the state of charge?", "Turn on the heater", etc.) Generally, I find these solutions not very user friendly at all and not well integrated. And I'm personally a bit wary about the security of it all. Giving a 3rd party access to my calendar is one thing; letting them control my car is something different.
  - dzhiurgis 5y ago
    Well it’s changing your temperature or opening window at most, not driving off a cliff

pests 5y ago

Tesla suggests only 80/%90% anyways as complete fill/drain cycles degrades the battery faster.

3pt14159 5y ago

I'm sort of perplexed that this is even a problem? Surely it's possible to dynamically disengage the charging mechanism once full?

r1ch 5y ago
The problem is that batteries themselves don't have a concept of "full". Measuring the state of charge in Li-ion cells is not easy as the voltage curve can be quite flat, so you have to use all kinds of heuristics to determine what a safe charge level is.
- 3pt14159 5y ago
  I see. Thanks. I take it thermal differential between battery and outdoor air won't work for some reason?
  - r1ch 5y ago
    Batteries heat up depending on the rate of charge and while it is easy to measure and control to avoid damage from overheating, I don't believe it can be used to measure the state of charge. Charging at home in a garage would likely be using a much slower (and thus cooler) charging method than a commercial charger, so I don't think the fires are caused by the rate of charge, but perhaps by over-charging potentially worn or damaged / defective cells.
- turtlebits 5y ago
  Are you sure that's correct? The BMS should have a high voltage disconnect and not allow further charging.
  - r1ch 5y ago
    I'm sure it does - the problem is that the disconnect trigger voltage could be a normal state of charge for one cell but a high / dangerous state of charge for another.

didntknowya 5y ago

i think most chargers (phone etc) have a "don't leave unattended while charging" warning as well just to cover their bases.