[sciencegeek]

So I thought I'd model range on the basis of the data I have gathered in conjunction with known physical effects (for elevation and drag) and empirical data (for AC use and baseline energy consumption). I also included a stop-and-go penalty at low speeds (since low average speeds imply frequent stops / slowdowns for lights and such). I'm assuming that driving style is 'normal'. Not too much babying and not too aggressive. Also, no headwind/tailwind or modeling of the thinner air at higher altitudes (which does make a difference for drag).

There are two tables, one for range as a function of speed and temperature, and one for range as a function of speed and elevation gain (loss). See if this matches your experience ... it looks pretty good to me overall (though I have no first-hand experience with very low or very high temperatures yet).

 

[Chewy]

How do your charts correlate with my experience?

Driving condition....

Cruise set to 65mph, though of course average is lower.

Ambient of around 6 degC to 8degC.

Comfort Drive Mode

Full Regen

HVAC set to 22degC

18” Wheels.

Total distance travelled from 100% SOC is 245 miles with 2% SOC at end.

 

[Chewy]

The images could not be loaded. Not sure why, they show fine on the UK I-Pace forum.

 

[dtgsrq]

140mi of highway (75mph) range at ambient (70F) temps seems low, and would certainly be disappointing. I haven't 'maxed out' range on a trip yet but based on my medium length trips (100+ highway miles) I'm anticipating more like 180mi at those conditions, still 25% off 'advertised' range. Range of 140mi would imply a 40% hit for highway speeds. Sure hope not!

 

[Calidave]

Definitely appreciate the science!
But, in my limited experience, the higher-speed ranges on the chart appear low. I'm on 18" wheels, Cali "winter" weather, and am well over 200 miles @ 65-70mph.
If I see a correction to that, I will report back.

 

[sciencegeek]

Remember that we're talking averages and 'normal' driving. chewy you are the master at driving conservatively! 45mph, 260 miles, that's really great. Can anyone else match your range is the question!

I do agree that higher speeds seem a little off ... but then again I haven't seen a real 75mph average by anyone. Drag is four times worse at 75mph than at 37.5mph ...

 

[Chewy]

I plan to do a 70mph run when the weather picks up. Not much point in Winter conditions as we know it will be low.

The images that didn’t plot showed average of 50mph in one direction for 117 miles with 3.33 miles/kWh. The return trip was 47mph average with 116 miles showing 3.02 miles/kWh. The return trip was in strong winds with quite heavy rain ?. This was on a single charge with total day’s mileage of 245 which includes the short trips to and from the office. 2% SOC left suggests that 260 miles would be possible.

Pretty sure if I tried this on 22” wheels then the range would be less, possibly by as much as 20 to 30 miles.

 

[Chewy]

I will be doing few coast downs in my car when I can find some time. If someone with 22” wheels could do the same then I could compare. Will also need the weight of your car with you in it.

To do a coastdown run we need to get the car up to 80mph on a long flat and smooth road surface. The car is then put into neutral and allowed to coast to a stop. The speed and time as the car coasts down need to be recorded. It is best done with something like a VBox.

Normally the test is carried out in both directions on the road, to eliminate any slight gradient effect.

From this data we will be able to work out exactly what power is required to hold the car at any particular speed.

It is unlikely that you will find a long enough straight bit of road for this, so the test can be broken down into different sections, say 80mph to 70mph, 70moh to 60mph, 60mph to 50 mph, etc....

 

[Calidave]

Remember that we're talking averages and 'normal' driving. chewy you are the master at driving conservatively! 45mph, 260 miles, that's really great. Can anyone else match your range is the question!

I do agree that higher speeds seem a little off ... but then again I haven't seen a real 75mph average by anyone. Drag is four times worse at 75mph than at 37.5mph ...

If helpful, I believe there have been quite a few 70mph tests: early out of the Netherlands, maybe Teslabjorn, and most recently Kate and James, who showed 170 miles range -- nighttime, UK winter conditions, and I'm pretty sure larger wheels.


Also good to keep in mind that EPA Est. @ 234 is mixed driving. So, range figures at constant higher speeds aren't "off" or a "miss," they're just at different conditions.



Admittedly, my sampling may be too small, but my initial driving behavior of 90% nightime uncongested freeway driving @ 65-70 mph, fan @ 3, cabin warming to ~70 and my current estimated range @ 100% is 227 miles.


Also have notice that consumption at low-speed "village cruising" (25mph through Pacific Grove) suggests the car could go on forever . . .

 

[PGhiron]

The one factor that is being left out is climate control. The difference between it being on or off is as much as 25% of the total mileage based on the temperature. I have seen this real world, and driving with it off and using seat heating or cooling really helps up the range. If you really hate the cold then run the climate for 10 min and then shut it off after the seat heaters get up to temp. The mileage bump is significant in my experience.

 

[sciencegeek]

I added a consumption rate constant [kW] for each of the different outside temperatures. But now that you mention it, I neglected to account for the fact that at higher speeds and extreme temperatures the battery is more effectively cooled or heated, and so there should be a speed-dependent term .. which I did not include.

Everyone please keep real world numbers coming (with *average speeds*) ... I will redo this at some point. It's mostly supposed to show trends anyway ... our mileages will vary.

 

[Calidave]

Can I ask a Newb Battery Math question here?


I parked yesterday with 20% charge, 50 miles of range.


Hooked up to my home 240v charger, charging at 10A, 2.4kwh; and charged for 10 hours, showing 24 kwh total charge.


Now the car shows 90% charge 195 miles range. I figured the 24kwh would only bring me to 50%+ charge, and it would
take me another night's charging to entirely fill the 80kwh battery (as filling 80% of the battery would require 60+kwh total input via the charger).


Would anyone be willing to offer an explainer? Many thanks.

 

[sciencegeek]

You're charging at >10Amp

 

[Calidave]

Thank you. So, my charger's numbers are off. I started to figure that if there's an error, it's with the charger . . .

 

[WattAJag]

Normally, 220/240v chargers are putting out 6.6KW. That's what's "normal". That should give you about 8% of an I-Pace SOC per hour or about 20 miles. As, a reasonable rule of thumb, you'll need to charge 2 hours on a 220v charger for every hour you drove in city driving to replenish the power used.