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EVEZY code d55d6 *** Try my car cost calculator
'19 BMW i3 120Ah / '20 Hyundai Kona 64kWh
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Discussion Starter #1 (Edited)
Had a brainwave: should manufacturers start installing pitot tubes in EVs? Surely that would endow the car with more data from which to more accurately estimate remaining range?

In the meantime, I’ve stumbled across this - which doesn’t seem to have been mentioned on here before:

Tesla Winds and Elevation

Seems like it could be useful, especially given that A Better Route Planner doesn’t (yet) handle the wind issue very effectively.

(It seems like it can be used just on a phone browser as well as on a Tesla in-car browser - so should be useable by drivers of any EV)
 

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This is why EVs will struggle to become mainstream until range and charging is 'brainless'.
Aside from speed record attempts, who in the ICE world worries about a slight head wind?
 

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EVEZY code d55d6 *** Try my car cost calculator
'19 BMW i3 120Ah / '20 Hyundai Kona 64kWh
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Discussion Starter #4
This is why EVs will struggle to become mainstream until range and charging is 'brainless'.
Aside from speed record attempts, who in the ICE world worries about a slight head wind?
Well, the idea is that the car would have pitot tube(s), and from that be able to automatically take into account the effect of wind (or more accurately), and thus provide a more accurate range estimation.

From what I've been learning since having an EV, wind is probably the most important factor which can't be controlled.

So the driver wouldn't then have to worry really about the wind because it would have been factored in by the car, automatically. The range estimation would be accurate (taking into account other factors too), and when (if) more navigation systems work like they do in a Tesla with respect to planning charging stops, the driver will just have to follow the plan.

At the moment, even something like A Better Route Planner only relies on rough, blunt data on wind.
 

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Well, the idea is that the car would have pitot tube(s), and from that be able to automatically take into account the effect of wind (or more accurately), and thus provide a more accurate range estimation.
Of course it could just get current and forecast wind speed and direction from something like www.windy.com
 

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EVEZY code d55d6 *** Try my car cost calculator
'19 BMW i3 120Ah / '20 Hyundai Kona 64kWh
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Discussion Starter #7
Not sure this would be necessary as the car knows the speed it's doing and how much power it's taking to maintain that speed in whatever the weather is doing.
Agreed - although isn’t that really just an instantaneous measurement - and then the GOM sort of extrapolates that? I think that’s how, in the i3 for example, the GOM estimates the range when you plug in a destination. Except I don’t think it takes into account ‘weather’ (wind, rain etc) - just temperature (although it technically could).

I was thinking though that a live measurement of the actual wind at surface level would still be useful if it could be used in tandem with wind forecasting to estimate the effect on consumption for the entire route.

So, you’re driving along and the forecast surface level wind is a 10mph headwind, but the car pitot tube only measures it to be 5mph. The GOM could then apply that adjustment to the rest of the route.

The reason I thought of this is because I’ve been looking at windy.com and see, for eg, 10mph headwinds forecast at surface level. So I plug that into A Better Route Planner and it has a fairly drastic effect on the range. But in reality, the impact on consumption car when actually driving the route is much less. Now, obviously there’s a whole load of things that could be causing the discrepancy there, but it just struck me that the car has a thermometer, so why not a means of measuring the head/tail wind too..

Anyway, enough thinking for now - time for gin!
 

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So the driver wouldn't then have to worry really about the wind because it would have been factored in by the car, automatically.
Most ICE cars have a range estimator. They are 'good enough' that you'll know you need to fuel up in the next 50 miles or so - no worry involved. As mes says, the car knows how much energy it is using to go each mile and that is a decent value (averaged suitably) to use for range estimation.
EVs need to get past this 'worry' stage. In some respects trying to factor in things like the wind, which at road level may be quite different to forecast anyway, is just reinforcing the biggest 'problem' in the minds of potential EV drivers.
 

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I think combining weather data with navigation would be more useful for calculating range than measuring local wind speeds. You want to predict the future not measure the here and now. If range estimates varied with wind measurements the value would bounce up and down erratically on a windy day depending on local topography or driving past a building.

That said I don't think the range estimate has to be that accurate. It's an estimate.
 

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EVEZY code d55d6 *** Try my car cost calculator
'19 BMW i3 120Ah / '20 Hyundai Kona 64kWh
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Discussion Starter #11
I do agree in principle with everyone’s comments - for the majority of the public, it just needs to be a non-issue. I think it’s just that I just like data and info screens though, so the more the better from my POV!!

I’m not too sure on the point about ICE cars having range estimators that are good enough, and the worry factor about range though - because the relative impact of a head / tail wind on the range of an EV is much greater than for an ICE car due to the far higher efficiency of the electric powertrain.

In an ICE car, the remaining range may read (for eg) 25 miles, and/or the fuel light comes on - but if the car is then driven into a strong headwind the extent to which the wind will quicken the reduction of that remaining range will be much less than in an EV (everything else being equal). So I think there is a greater importance for accuracy in the range estimation for an EV. I think this will be the case regardless of total range, and charging capability/availability - A LOT of people still manage to run out of fuel in ICE cars with ranges more than double that of most EVs, and with fuel stations all over the place.

The thing about EVs is that they currently have probably appealed to and have been driven by people of higher than average intelligence (just a hunch!). That won’t always be the case...!
 

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EVEZY code d55d6 *** Try my car cost calculator
'19 BMW i3 120Ah / '20 Hyundai Kona 64kWh
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Discussion Starter #12
think combining weather data with navigation would be more useful for calculating range than measuring local wind speeds.
Agreed - it’s just that getting accurate local wind speed and direction data seems to be very difficult unless you are measuring it on the go. That’s the thinking behind my idea of the car pulling data from a wind forecast (or nowcast) map, but then comparing that data to what it actually measures and then applying an adjustment to the wind data for the programmed route, and adjusting the range estimate accordingly. The driver need not know any of that is happening - they just see a more accurate range estimation, which I believe is more important in an EV than in an ICE car because of the far higher efficiency of the EV drivetrain.
 

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the relative impact of a head / tail wind on the range of an EV is much greater than for an ICE car due to the far higher efficiency of the electric powertrain.
At the risk of becoming donald, do you have any evidence to back that claim?
To be honest it sounds like cobblers to me, but I'm happy to be proved wrong by appropriate science.
 

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EVEZY code d55d6 *** Try my car cost calculator
'19 BMW i3 120Ah / '20 Hyundai Kona 64kWh
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Discussion Starter #14
At the risk of becoming donald, do you have any evidence to back that claim?
To be honest it sounds like cobblers to me, but I'm happy to be proved wrong by appropriate science.
None at all - it just seemed like common sense to me tbh..! (That's not to say I couldn't be wrong!)

Surely, for an already less efficient (ICE) car, the impact of the same thing (eg an x mph headwind) negatively affecting efficiency at the same rate isn't as significant as it is for a highly efficient EV. If my i3 normally averages 4 mi/kWh (250wh/mi), but then a headwind develops and reduces that to ≈3 mi/kWh (325wh/mi) (a 30% efficiency hit), then the increased consumption means I can only drive 75% of the distance I could have without the headwind. But, with an ICE car (of equivalent Cd), where the equivalent efficiency is, let's say, perhaps 1.0 mile/kWh (1,000wh/mi or about 40 mpg(e)...), then the same 75wh/mi wind penalty only results in a 7.5% efficiency hit, and I can still drive 93% of the distance I could have without the headwind.
 

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EVEZY code d55d6 *** Try my car cost calculator
'19 BMW i3 120Ah / '20 Hyundai Kona 64kWh
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Discussion Starter #16
My common sense said other, but now I'm wondering.
Is that an actual example from your car data or just numbers made up for example?
Just made up..!
 

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Just made up..!
:)
I think there probably will be a difference, but maybe not huge. It hangs on the balance of the various losses in the two types and it would take some digging to find those out.

Basically, at constant speed, there are for both types:
- Air resistance
- Rolling resistance
- Drivetrain losses
- Auxiliaries
These should be similar and constant for both and will be equal to the useful power output from the prime mover (with some conditions).

For BEV there are:
- Battery losses
- Invertor losses
- Motor losses
and for ICE there are:
- Thermodynamic efficiency losses
- Friction losses inside the engine

The biggest ICE losses are the thermodynamic efficiency which will only be perhaps 40%, so 60% lost, basically down the pipe. But that loss is proportional to the load, so also increases with headwind.

If the load increases due to a headwind then with both types the useful power needs to increase. For a BEV the power comes from the battery plus an increase the extra losses above. For an ICE the power comes from the fuel plus an increase in the thermodynamic 'losses' - but the engine friction loss remains the same.
So as a proportion of the total energy in play I think the engine friction losses will be the main 'unbalancer' of the change in range, since most other energy use is either the same or proportional to the increased load.

As I said, it would need actual numbers to demonstrate this properly but as a thought experiment lets take a constant speed, no wind, and ICE engine friction is 10%. For the BEV battery use is say 100 units and so for the ICE fuel use will be 110.
If a headwind increases the required power at the wheels by 20 units the BEV needs 120 units and the ICE 130. The BEV thus needs 20% more 'fuel' (20/100) whereas the ICE only needs 18% (20/110). So there is a difference, but (in this example) not very much.

I suspect I'm going to need a tin hat now :eek:
 
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