5 ms·

Hm, even LED TVs use something like 30W, don’t think you’d get much out of dimming a tablet sized screen. 50W for 5 hours is 250Wh, which is a mile extra range

Hm, even LED TVs use something like 30W, don’t think you’d get much out of dimming a tablet sized screen. 50W for 5 hours is 250Wh, which is a mile extra range. That’s worth having.

kenhwang 7y ago
Tesla's speaker system is 200/560W. So it's possible to get to 50W just from screen and speaker savings. And that's assuming constant worse case use of the wipers: high speed and full load like you're driving through a waterfall. Pulling up a spec sheet for a wiper motor, it looks like normal load is only supposed to draw ~6-10W.
- jerf 7y ago
  This sort of thing is why I refer to "the noise floor" in these sorts of discussions. It's not that it's untrue that it may save a mile of range, it's just so dominated by other factors that it doesn't matter. Your human cognitive spotlight is focusing on this one fact, and it may be "true", but that doesn't make it important. It's not worth engineering effort to save amounts of power that will be casually wiped away by any number of little things. (Sometimes you can bind together several little things into one big one worth doing, but human intuition is still often broken by the factors of magnitude involved. 6 %.0002 things still don't add up to anything significant, for insurance, even if it may feel like six things ought to matter.)
- close04 7y ago
  On the other hand even a 1 mile (probably less) saving over a 5 hour (~200-250mi) trip through the rain might as well be a rounding error regardless of the fuel used. Many other methods for achieving the same saving are not as flashy though. I imagine the most important way is to ensure optimal tire pressure at all times. Many people tend to ignore this even when having pressure sensors at hand which leads to a whole lot of wasted fuel. The reason wipers only received minor optimizations over the decades is because they work well, are cheap and enviably reliable. So any new wiper system design has a high bar to pass, beyond using new tech.
rumanator 7y ago
> 50W for 5 hours is 250Wh, which is a mile extra range. That’s worth having. That represents about 0.5% of a Tesla's advertised range.
- dannyw 7y ago
  You do 10 of these things and you have 5% better range, more than your competitor who ignores 0.5% savings.
  - drusepth 7y ago
    While I agree with you and am excited for whatever improvements can be made, I think the most likely retort to this argument is "While you're worrying about 10 0.5% savings, your competitor is focusing on optimizing things that actually matter."
  - mlyle 7y ago
    Calling it 0.5% is generous. * Only when it rains. (It's worthless the rest of the time) * Only if all of the motor power is saved. (Presumably the new mechanism uses some power) * Only if the motor is running at full power the entire time it rains (even on "high" this is not true). * Only if range is not otherwise impacted by the rain (nope). If it rains all the time, and the above are all true-- yes, it's worth 0.5%.
  - deleted 7y ago
    [deleted]
matt-attack 7y ago
What’s funny is all of these trade offs have always applied to ICE cars as well, but for some reason no one cares. Blasting your radio shortens your range even in a gas vehicle. Running your wipers shortens your range even in a gas car.
- deleted 7y ago
  [deleted]
- ricardobeat 7y ago
  "some reason" being you can just add an extra liter to the fuel tank, not the case for batteries.
  - TheTruth321 7y ago
    WTF .... Are HN posters really this dumb? ... is what i would have said.
- deleted 7y ago
  [deleted]
- jondumbau 7y ago
  I'm not much for electronics. Can you explain how playing the stereo affects mileage?
  - wffurr 7y ago
    Additional power draw on the accessory circuit places increased load on the alternator which in turn causes the engine to run a little harder than it otherwise would. Thus burning a little extra fuel.
    - jondumbau 7y ago
      Cheers, alternators are essentially magic to me. Id have presumed they were generating 'enough' power at all times the engine was running.

Hm, even LED TVs use something like 30W, don’t think you’d get much out of dimming a tablet sized screen. 50W for 5 hours is 250Wh, which is a mile extra range. That’s worth having.

kenhwang 7y ago

Tesla's speaker system is 200/560W. So it's possible to get to 50W just from screen and speaker savings. And that's assuming constant worse case use of the wipers: high speed and full load like you're driving through a waterfall. Pulling up a spec sheet for a wiper motor, it looks like normal load is only supposed to draw ~6-10W.

jerf 7y ago
This sort of thing is why I refer to "the noise floor" in these sorts of discussions. It's not that it's untrue that it may save a mile of range, it's just so dominated by other factors that it doesn't matter. Your human cognitive spotlight is focusing on this one fact, and it may be "true", but that doesn't make it important. It's not worth engineering effort to save amounts of power that will be casually wiped away by any number of little things. (Sometimes you can bind together several little things into one big one worth doing, but human intuition is still often broken by the factors of magnitude involved. 6 %.0002 things still don't add up to anything significant, for insurance, even if it may feel like six things ought to matter.)
close04 7y ago
On the other hand even a 1 mile (probably less) saving over a 5 hour (~200-250mi) trip through the rain might as well be a rounding error regardless of the fuel used. Many other methods for achieving the same saving are not as flashy though. I imagine the most important way is to ensure optimal tire pressure at all times. Many people tend to ignore this even when having pressure sensors at hand which leads to a whole lot of wasted fuel. The reason wipers only received minor optimizations over the decades is because they work well, are cheap and enviably reliable. So any new wiper system design has a high bar to pass, beyond using new tech.

rumanator 7y ago

> 50W for 5 hours is 250Wh, which is a mile extra range. That’s worth having. That represents about 0.5% of a Tesla's advertised range.

dannyw 7y ago
You do 10 of these things and you have 5% better range, more than your competitor who ignores 0.5% savings.
- drusepth 7y ago
  While I agree with you and am excited for whatever improvements can be made, I think the most likely retort to this argument is "While you're worrying about 10 0.5% savings, your competitor is focusing on optimizing things that actually matter."
- mlyle 7y ago
  Calling it 0.5% is generous. * Only when it rains. (It's worthless the rest of the time) * Only if all of the motor power is saved. (Presumably the new mechanism uses some power) * Only if the motor is running at full power the entire time it rains (even on "high" this is not true). * Only if range is not otherwise impacted by the rain (nope). If it rains all the time, and the above are all true-- yes, it's worth 0.5%.
- deleted 7y ago
  [deleted]

matt-attack 7y ago

What’s funny is all of these trade offs have always applied to ICE cars as well, but for some reason no one cares. Blasting your radio shortens your range even in a gas vehicle. Running your wipers shortens your range even in a gas car.

deleted 7y ago
[deleted]
ricardobeat 7y ago
"some reason" being you can just add an extra liter to the fuel tank, not the case for batteries.
- TheTruth321 7y ago
  WTF .... Are HN posters really this dumb? ... is what i would have said.
deleted 7y ago
[deleted]
jondumbau 7y ago
I'm not much for electronics. Can you explain how playing the stereo affects mileage?
- wffurr 7y ago
  Additional power draw on the accessory circuit places increased load on the alternator which in turn causes the engine to run a little harder than it otherwise would. Thus burning a little extra fuel.
  - jondumbau 7y ago
    Cheers, alternators are essentially magic to me. Id have presumed they were generating 'enough' power at all times the engine was running.