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Hi.

What's the furthest you've managed to travel on a single trip on a highway travelling at around 65 to 70mph?

This is just using the battery.

Thanks
 

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Hi Kal,

I’m jut going to jump in from the outset to say there has been quite a lot of discussion recently about energy consumption at motorway speeds, and the different results that people report.

There are so many different variables, including factors that can’t be controlled. One of the most significant is whether or not there was a tail wind.

I would recommend having a play with www.abetterrouteplanner.com and seeing what impact different parameters has.

Also take a look at eCalc - evCalc - independent Range and Efficiency Calculator for Electric Vehicles/Cars (EV's) with Benchmarking

For an i3 120Ah, with a 37.9 kWh useable battery capacity (assuming zero degradation), I estimate a total distance of roughly 150-160 miles could be covered at 65mph with zero wind, at 20°C, on dry roads.

This is based on an average 4.0 mi/kWh under those conditions, so the total theoretical distance could be calculated for an older i3, or for a journey which ends with x% of battery remaining using that 4.0mi/kWh figure.

For example, in reality, you probably wouldn’t / couldn’t go below 5% remaining battery at the absolute minimum - so that would make the answer to the question about 145 miles for a 120Ah i3 (@65mph, no tailwind).

[EDIT TO ADD - for a 94Ah i3 (27.2 kWh useable), this would imply a range at 65mph under the above conditions, from 100% to 5% SOC of about 103 miles.

With a constant and perfectly directed 5mph tailwind, ABRP estimates, theoretically, that efficiency would improve to 5 mi/kWh. 5 x (95% of 37.9) = 180 miles. [EDIT TO ADD - or 129 miles for a 94Ah i3)
 

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At a real 70mph, you are looking at 3.5 mi/kWh
(no wind, 20°C etc) - giving a 100% to 5% range of about 125 miles (120Ah i3).
[EDIT TO ADD - or 90 miles for a 94Ah i3]
 

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What's the furthest you've managed to travel on a single trip on a highway travelling at around 65 to 70mph?
Last time I headed for London, I managed to get to Reading Services (98 miles approx) with about 12% on board so theoretically around 110 miles. Wasn't too warm though but probably had a tailwind of some description. Got to be honest, in a used BEV, I wouldn't count on any more than 100 miles at a real 70mph before the bum starts to get squeaky.

OP has a 94ah so 3.5 mi/kWh at 27.2kWh capacity is 95.2 miles.

Really hard to know as there are so many variables including ambient temps, real average speed that can be maintained, road conditions, weight and moreover, how much degradation the battery has.

Reducing each mph will make a huge difference.
 

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I know I keep banging on about it, but I can’t really recommend ABRP highly enough if you are going to be embarking on a journey where the range of any EV they have a model for is going to be tested.

Before you set off, use ABRP to enter the journey details and paramaters. Look at www.windy.com to get a quick visual idea about the winds you will encounter.

Then use ABRP in the live follow mode whilst you are driving and compare the predicted SOC with what you actually have along the route, and then update the actual SOC on the move - it will then adjust the plan.

Unfortunately there doesn’t currently seem to be a way for ABRP to use live data form the i3 to do this - but people with various other cars can do this automatically.
 

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Reducing each mph will make a huge difference.
Surely this is all part of the mental pre-departure planning process. If I am going to be on range anxiety limits, then I will look carefully at the route and my speed. I see little point in driving at 70mph to get somewhere which would require a top up on the way, when a more sedate speed will get me there with range in hand. I have long thought that 50 mph average speed zones are just what is needed for the EV era. It is rather comforting driving along and seeing the GOM range increase.
 

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Discussion Starter #8
I know I keep banging on about it, but I can’t really recommend ABRP highly enough if you are going to be embarking on a journey where the range of any EV they have a model for is going to be tested.

Before you set off, use ABRP to enter the journey details and paramaters. Look at www.windy.com to get a quick visual idea about the winds you will encounter.

Then use ABRP in the live follow mode whilst you are driving and compare the predicted SOC with what you actually have along the route, and then update the actual SOC on the move - it will then adjust the plan.

Unfortunately there doesn’t currently seem to be a way for ABRP to use live data form the i3 to do this - but people with various other cars can do this automatically.
Thanks for the links. ABRP seems really useful.
 

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Surely this is all part of the mental pre-departure planning process.
Thanks for the links. ABRP seems really useful.
It really is excellent - and all developed by one bloke (with the help of another 1 or 2 others recently I believe) who purchased a Tesla and then found that even the already very good Tesla route planning software wasn't really as good as it could be (and also couldn't be used to pre-plan without sitting in the car).

ABRP can recommend when it is necessary, or just more time efficient, to drive more slowly. (Obviously, there are limitations though - so it can't currently foresee that driving faster and consequently needing to stop for a charge may be quicker on paper, but may in reality be slower if someone is already using the single charger).

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Surely this is all part of the mental pre-departure planning process. If I am going to be on range anxiety limits, then I will look carefully at the route and my speed. I see little point in driving at 70mph to get somewhere which would require a top up on the way, when a more sedate speed will get me there with range in hand. I have long thought that 50 mph average speed zones are just what is needed for the EV era. It is rather comforting driving along and seeing the GOM range increase.
I wasn't suggesting anything different to that ;)

I generally drive at 58mph (real 56mph) on the motorway these days. It avoids dodging in and out of most HGVs that are sat on cruise too and just makes for a far more relaxing day.
 

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Really interesting post in terms of the timings and I know you are not advocating this but the trouble is, it's this kind of thought process that encouraged people in ICEs to hurtle around at 90mph on motorways regardless of the fuel consumed just because it got them from A to B quicker. That journey is quicker but it's also 22% less efficient if I'm reading it correctly.

Surely the aim should be to balance efficiency with speed, not time with speed or we'll be back to square one. And whilst we can all champion low emissions and renewable leccy, it's still no reason to burn it for burning it's sake as it all has an overhead somewhere.

Have to say, it is one of my disappointments that the offers from many companies have enormous performance potential. It's a bit of an anachronism to me that a technology built on the premise of changing the way we travel for the better should produce cars that are inherently inefficient in the manner in which they are likely to be driven. I guess that is marketing though and may be a necessary evil to get people to shift their mindset.
 

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I don’t disagree. There’re other considerations too though, I think. One that comes to mind is, if I was driving for 8+ hours from London to Edinburgh, unless I had a fully autonomous car where I could go to sleep, or work etc, then I think I would find driving for that long at 60mph on motorways to provide too little stimulation to keep me sufficiently alert, to the point of it starting to increase the risk of a momentary lapse of concentration leading to an accident.

Also, where do we stop? How much less efficient is 60mph vs 50mph? (21.5%)

I definitely think more car manufacturers should be focusing more on lightness and potential efficiency, rather than producing heavy, inefficient SUVs. I’m not sure that performance necessarily needs to be limited - the i3 and Model 3 are good examples of cars that are efficient and can also offer good performance due to optimisation of things like weight, rolling resistance and aerodynamics. The impact of performance actually used on overall real efficiency is probably quite limited, I suspect.
 

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I generally drive at 58mph (real 56mph) on the motorway these days. It avoids dodging in and out of most HGVs that are sat on cruise too and just makes for a far more relaxing day.
I'm not meaning to be argumentative here - just illustrating there are always trade-offs - but, in effect you are prioritising your convenience (and safety) of not having to dodge in and of HGVs over the potential efficiency saving and environmental benefit that could be realised if you drove at 50mph (or less even) instead.

At the risk of straying off topic - I tend to believe that many of the people driving 75-80mph+ on motorways are being swept along with the traffic flow, and this is often a result of inattentive or poorly educated drivers cruising in the middle lane when there is no need to. I sometimes get the impression that a majority of those travelling 80+ don't really want to be doing those speeds...on quiet motorways I tend to find most people stay closer to 70 because there isn't that flow to be swept along in, nor the middle lane hoggers to pass, or the peer pressure to succumb to. (Obviously there will always be those that take advantage of an empty motorway to push on at 90+).
 

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I'm not meaning to be argumentative here - just illustrating there are always trade-offs .......
I have found that in the past I made decisions over speeds on motorways based on distances between services, and the car's range, to leapfrog some but still leave a safety margin to get to the next one. In the Leaf 24 that sometimes meant driving very conservatively because stopping every second services worked out fine but it was a challenge to skip two without hypermiling. Making motorway speeds of 70 mph only possible for short hops.

With increasing car range, such considerations are far less important and it's now possible to just keep up with whatever traffic conditions are there and which present the safest options whilst making good progress. The efficiency aspect is now much less important and at the end of the day only makes a few quid difference in cost even over long trips. Still of academic and bragging rights importance though.
 

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The efficiency aspect is now much less important and at the end of the day only makes a few quid difference in cost even over long trips. Still of academic and bragging rights importance though.
It would be interesting to calculate the additional environmental cost that would be borne over the course of a year if the total amount of UK motorway miles were all driven by EVs driving at 80, at 70, and at 60, and then to compare that to an average ICE car at 80, 70 and 60.

Any volunteers? @donald ?

I hope and expect that the net negative impact of a UK fleet of EVs doing 80 or 70 instead of 60 is going to be significantly less than the net negative impact of a UK fleet of ICE cars doing those higher speeds instead of 60.

Then we get into considering the other trade-offs..safety, time spent on the road, noise etc etc. A good deal of these (esp. safety and productive time lost) may well eventually be negated by the advent of fully autonomous motorway driving.
 

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Then we get into considering the other trade-offs..safety, time spent on the road, noise etc etc. A good deal of these (esp. safety and productive time lost) may well eventually be negated by the advent of fully autonomous motorway driving.
There is a danger in becoming too anal over any global environmental issues with relatively small incremental differences in speed imo. I know that the equations over velocity and energy are exponential and that every 10 mph increase makes a massive difference in power usage. But as you say, the tradeoff in safety and personal time is of much more interest to the average driver.

A potential huge saving in both energy and safety is over 'platooning' of cars that are autonomous. A pilot has been running in California for some years where many cars 'latch on' to each other and drive as a virtual train along freeways with distances of a couple of feet apart. The lead car is constantly talking to the platoon and each car brakes and accelerates at the same instant as required. Such a convoy would be mega efficient purely from the slipstream effect but also from AI that would be even superior to an @donald hypermile plan.

Such a platoon system would truly enable each driver to hand over control of a distance journey in confidence and still enable them to exit the convoy as required with the following car closing ranks as one leaves. Super efficiency with safety once all Manufacturers agree on a common interface.
 

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I'm not meaning to be argumentative here - just illustrating there are always trade-offs - but, in effect you are prioritising your convenience (and safety) of not having to dodge in and of HGVs over the potential efficiency saving and environmental benefit that could be realised if you drove at 50mph (or less even) instead.
You are not being argumentative and I hope I'm not either :)

You're right, I am choosing to drive at 56mph for a number of reasons and I could drive more economically or ultimately not at all of course. But there comes a point where realism kicks in.

My point was, the speed limit is 70mph so I have never been able to understand any car being allowed on UK roads with a top speed much greater than that and I can't really see the practical benefit of being able to reach the speed of light in under 10 seconds. Whether you choose to travel at 56 or 70mph is a matter of choice but energy efficiency should be in the consideration somewhere, not just time.
 

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Whether you choose to travel at 56 or 70mph is a matter of choice but energy efficiency should be in the consideration somewhere, not just time.
I guess, ultimately, energy efficiency is already considered by most people - it's just that it's normally considered with respect to the linked financial cost (the private cost) , rather than the environmental impact of higher speed (the external costs), and the financial penalty of driving faster in a modern diesel engined car must be less significant than it would be if most cars were still powered by naturally aspirated petrol engines.

Then there's the perceived time opportunity benefit of driving faster, which most people probably subconsciously and substantially over-estimate.

Perhaps one day, a road user pricing system will exist that not only charges drivers per mile, but also varies that charge for motorway miles according to different speed bands.

So, of you drive 100 miles up the M1, the base road user charge is 100 x 20p = £20 for everyone. (for eg)

But, if the system measures that your average speed - whilst above 40mph (to discount congestion) - was 50-60mph, then your per mile rate is reduced to 15p, so you pay just £15.

If your average was 60-70mph you pay £20.

If it was 70-75, you pay 30p per mile, so £30.

If it was 75-80, you pay £1 per mile, £100.

If it was 80-90, you pay £X per mile (X = [your gross annual income / 365)] / 20)

If it was 90+, you pay the 80-90 charge, and receive a bonus court summons.

(The above figures were just quickly made up to illustrate the idea, and may be completely inappropriate).
 

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Hi.

What's the furthest you've managed to travel on a single trip on a highway travelling at around 65 to 70mph?

This is just using the battery.

Thanks
i average about 220 km per day , on the motorway, warm to mild temperature, i find a strong headwind really knocks the range. i drove 86km this morning, at 75mph on average, and used 15 kwh
 
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