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Discussion Starter · #1 ·
Tried to simulate driving a long distance trip in Excel (see attached) for the I-pace calculating total time, total kwh charged and cost at 4 different highway speeds. I build it for Metric and Imperial system.

The calculations are driving by various assumptions that can be adjusted and some general assumptions to simplify the simulation. Key logic (although flawed) to simplify the simulation is that fast chargers are available exactly where you need them and they are all working and charging at the same constant charging speed, also that you depart with a 100% SoC.

Changeable assumptions:
  • Usable battery size of the car - set to 85kW
  • Battery charging speed - set to 50kW
  • Recharge to battery % - set to 80% SoC
  • % extra charge for last leg - set to 10%
  • Distance to travel - set to 1250km
  • Avg cost per kwh charged - set to €0.25
  • Ratio avg speed to highway speed
  • Fuel efficiency for the 4 different speeds

Any feedback, suggestions, corrections etc on the logic and/or calculations is welcome
 

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Discussion Starter · #3 ·
Nelsonste said:
So driving as fast as possible is still the way to get the quickest from A to B ;-)
Based on the assumed efficiencies - YES - the time gained by faster driving is more than extra time spend charging.
The higher charge rate is available the bigger the effects gets.

Warning is that efficiencies used are purely my estimates - I am looking for some one to give me real data. Although I hope that assuming just 225km range at 140km/h is conservative not aggressive.
 

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Hi Jelle,

Thank you for the effort that you've put in that!
Usefull information that we will hopefully soon be experiencing in practice!

Where did you take the consumption vallues from?
 

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Discussion Starter · #5 ·
Hi Jelle,

Thank you for the effort that you've put in that!
Usefull information that we will hopefully soon be in practice!

Where did you take the consumption vallues from?
No specific source - just rough own estimation. Whereby the 80km is based on WLTP 21.2kw/100km rounded up to 22. I validated it a little bit with the efficiency table that J2T2 shared in I-pace range discussion topic.

Hence my request to other forum members to validate assumptions/calculations and give feedback if wrong. Would be great to get actual data from folks that already have their I-pace.
 

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Thks a lot Jelle for your model that is critical for long trips.
I drove personally 200km at 140km/h on a motorway and my efficiency was about 28KWh / 100km therefore I would say that 300km is feasible at 140.
You should take into account how flat is the trip because the level of regen is quite important in the battery consumption average.
 

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Thanks Jelle and emgf,
With higher speeds you get more regen, so I can keep on driving the I pace in my old way with ICE car.
It is less than ten days a year that I drive more than 300 km in a oneway trip.
Very good news!
 

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Discussion Starter · #8 ·
Peter P said:
Thanks Jelle and emgf,
With higher speeds you get more regen, so I can keep on driving the I pace in my old way with ICE car.
It is less than ten days a year that I drive more than 300 km in a oneway trip.
Very good news!
True but that is only if you slow down from a greater speed - the main issue is that consumption goes up at higher speeds and for longer trips there is relative far less regen because you tend to travel for longer distances at sustained speeds.

This is why BEV cars get better city mileage than highway mileage compared to ICE cars that get better highway mileage than city milleage.
 

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I will upload my first week of trips this weekend. Daily roundtrip of 100 km in total and a few outliers of 230-300 km's. Maybe it helps. Not one real long trip, but you never know.
Fyi: Today I did approx 230 km mainly on Dutch high ways doing 100-130 km/h. No real heavy traffic. Only for a short distance (a long time tough). Got home with approx 90 km left on the GOM.
 

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Tophe74 said:
I ll do 320km this Friday, mainly on highway at 130km/h.
Will see how it goes.
I am very very curious how that will work out seems like sort of the max at that speed. Good luck!
 

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Tophe74 this 320km range on one charge will depend on the relief of the road and the level of regen you can get : going to Normandy I consumed
27KWh/100km and got 7KWh regen (one way )
Good luck
 

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Yes am curious to . Can't wait :)
If I saw I can't make it at 130km/h I ll reduce speed to 120 or 110.
I ll go from 600m to 100m altitude so the return trip will be harder
We will be 4 in the car. 2 adults and 2 childs so not to much weight, like 180kg and 20kg of luggages.
Stay tuned.
 

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Tophe74: I will be amazed (but very pleased for you and all of us) if you make it home at those speeds without a charge. A 500m climb, with the car weighing 2,400 kg with passengers, requires a theoretical 3.3 kW-hr at 100% efficiency, probably nearer 5kW-hr from the battery in practice. You may get temptingly near home with apparently lots of charge left, but it may all suddenly disappear once you start climbing.
And all the info available so far indicates that the fastest journey time will be to drive fast and stop for a brief charge; driving slowly does not increase the range by that much; stopping for a partial charge and driving fast will give the minimum journey time.
Good luck!
 

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Discussion Starter · #17 ·
J2T2 said:
Jelle, here is an Excel worksheet with my journeys showing average speed, efficiency and distance. Hope its of some use with your calculator. Sorry but its all in miles!
Thanks J2T2 - see your file a bit expanded showing now both metric & imperial data - you can select preference in cell Q17.
The top rows shows stats per avg speed group and per avg distance group.

If you like you can continue using this file and add trips from line 68 down - I added auto formatting so all you need to do is fill per each line column B, C and D as you have been doing. I will see if I can keep track as well from Sunday onward after I collected my own I-pace :D

Would like to see a few more trips showing higher average speeds but guess that is tricky as first you need to get to highway, then avoid traffic on the highway and at the end you leave the highway to reach destination.
 

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Nelsonste said:
So driving as fast as possible is still the way to get the quickest from A to B ;-)
At charging speed of 50 kwh, it seems the optimal speed is 120km/h as the extra charge at 140 km/h makes the total trip time more. Of course, this reverses when the battery charging speed is 100 kwh.
 

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Discussion Starter · #19 ·
mclarenpaul said:
Nelsonste said:
So driving as fast as possible is still the way to get the quickest from A to B ;-)
At charging speed of 50 kwh, it seems the optimal speed is 120km/h as the extra charge at 140 km/h makes the total trip time more. Of course, this reverses when the battery charging speed is 100 kwh.
Yes - that is the original reason why I build it to see what is the optimum speed, Think reality and more data can show what will be the real story because at the moment there is a lot of guestimates,

There is 1 element to consider is that when you are driving 100km/h on a highway with max speed of 120km/h you are much more likely to keep a constant speed and therefore greater efficiency. If you are driving 140km/h you will be driving faster than most others on the highway and therefore more likely will have to slow down and speed up again (good to have ACC) which next to lower efficiency due to higher speeds also creates waste of accelerating and braking (even with regen you do not recover 100%).
 

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Discussion Starter · #20 ·
Hoping to collect my I-pace this Sunday and then thinking of making some fuel efficiency test the following weekend.

I think I have found a really good place to test it - a triangle of 3 highways (A58 - A17 - A16) - just over 60km in length allowing me to drive at constant speed - the speed limit for the majority is 130km/h with a small part (just 3.5km) being 100km/h. So I can do the route multiple times each time at a different speed.
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Question of course is if with BEV it is the same as with ICE that the first 1,000km-2,000km are less efficient, I actually really hope it is as that means efficiency might improve a bit as all tests are done with brand new cars with very few with more than 1,000km driven.
 

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