3 ms·

It's interesting to compare the state of charge and range remaining graphs around this point. Remember the x-axis is miles, not time. The car does not appear

It's interesting to compare the state of charge and range remaining graphs around this point. Remember the x-axis is miles, not time. The car does not appear to have lost much charge overnight, but with a cold battery, it's discharging much faster just after he starts driving again. Thus the range remaining is pretty low, even though the battery is still charged. As soon as the battery warms up, the discharge rate becomes what it was the day before, even before he's got to the Norwich recharge station. For some reason though, the range remaining graph doesn't increase after the battery warms up, when you would think it should. From looking at these graphs, it doesn't look to me that there's a problem with losing charge, but there may be a problem with how the state of charge is reported as range.

sophacles 14y ago
If I was designing a "distance remaining" meter for a car like this. I would think long and hard about UX. For instance, does it make sense to have the reported distance available fluctuate? That sort of behavior could be taken quite negatively by users. It could make them distrust the meter. Similarly, there is a safety aspect of always reporting the lowest estimate made by the car, even if conditions have changed more favorably. Better to have someone recharge before strictly necessary than to have someone not realize that conditions have changed after making a decision to skip a charger, and to then run out of energy. I'm not saying this is what Tesla does, I am just saying that the considerations for the UI in this case are interesting, and maybe there were decisions and behaviors involved that are different than a simple function.
- tadfisher 14y ago
  In order to display a non-fluctuating distance remaining number, Tesla would essentially have to either predict the future or vastly under-report the real number. The car doesn't know whether you are stopping for 5 minutes in 20 degree weather or 10 hours, and UX would be even stranger would it attempt to guess for you. It looks like they already under-report to some degree, but under-reporting by 1/2 the remaining distance would seem to me to be much less ideal than the current solution, which is to adapt the number to conditions currently observed.
  - sophacles 14y ago
    Or they could report a "minimum safe distance remaining". Or some sort of warning that says "batteries unconditioned, don't trust readout". And so on. There are a lot of different things that don't require "doesn't exist in a good form yet" tech.
- deleted 14y ago
  [deleted]
- Someone 14y ago
  I am not even sure I would dare give a distance estimate. If I look at some mobile devices I have access to: Dell laptop: estimates time remaining in hours and minutes; in my experience, that estimate isn't reliable. iPod Touch: the most concrete it gets is a warning "20% battery charge remaining". Is likely to show it multiple times. The display only shows a tiny bar. iPad (and, I think, the iPhone): goes a bit further; can show a numerical battery percentage. For both iOS devices, the Settings app also shows a "Time since last charge" section with "Usage" and "Standby" times. It does not dare give a time remaining. Mobile phone: 5-bar battery full indicator. Back to the electric car: especially given the short range for a full charge, I understand owners will want a distance remaining estimate, but I would say: if you can't give a reliable one, don't. 'Percentage charge remaining' plus a 'at similar speed and weather, you typically would have stretched this for x miles' indicator, IMO, would be better. And that is even more than a gasoline powered car will give you.

sophacles 14y ago

If I was designing a "distance remaining" meter for a car like this. I would think long and hard about UX. For instance, does it make sense to have the reported distance available fluctuate? That sort of behavior could be taken quite negatively by users. It could make them distrust the meter. Similarly, there is a safety aspect of always reporting the lowest estimate made by the car, even if conditions have changed more favorably. Better to have someone recharge before strictly necessary than to have someone not realize that conditions have changed after making a decision to skip a charger, and to then run out of energy. I'm not saying this is what Tesla does, I am just saying that the considerations for the UI in this case are interesting, and maybe there were decisions and behaviors involved that are different than a simple function.

tadfisher 14y ago
In order to display a non-fluctuating distance remaining number, Tesla would essentially have to either predict the future or vastly under-report the real number. The car doesn't know whether you are stopping for 5 minutes in 20 degree weather or 10 hours, and UX would be even stranger would it attempt to guess for you. It looks like they already under-report to some degree, but under-reporting by 1/2 the remaining distance would seem to me to be much less ideal than the current solution, which is to adapt the number to conditions currently observed.
- sophacles 14y ago
  Or they could report a "minimum safe distance remaining". Or some sort of warning that says "batteries unconditioned, don't trust readout". And so on. There are a lot of different things that don't require "doesn't exist in a good form yet" tech.
deleted 14y ago
[deleted]
Someone 14y ago
I am not even sure I would dare give a distance estimate. If I look at some mobile devices I have access to: Dell laptop: estimates time remaining in hours and minutes; in my experience, that estimate isn't reliable. iPod Touch: the most concrete it gets is a warning "20% battery charge remaining". Is likely to show it multiple times. The display only shows a tiny bar. iPad (and, I think, the iPhone): goes a bit further; can show a numerical battery percentage. For both iOS devices, the Settings app also shows a "Time since last charge" section with "Usage" and "Standby" times. It does not dare give a time remaining. Mobile phone: 5-bar battery full indicator. Back to the electric car: especially given the short range for a full charge, I understand owners will want a distance remaining estimate, but I would say: if you can't give a reliable one, don't. 'Percentage charge remaining' plus a 'at similar speed and weather, you typically would have stretched this for x miles' indicator, IMO, would be better. And that is even more than a gasoline powered car will give you.