[Ambassador Spock]

A few weeks ago I did something quite interesting (to me) and also quite stupid - I wanted to see just how far I could push the 77 kWh battery of a First Edition VW ID.4! I had to drive from my home (near Peterborough in the UK) down to a village near Brighton to drop something off, and since I have nothing else planned for the day I figured that was the perfect opportunity to do a proper range test. It is something I will definitely never do again (I left the house at 5:20 AM and didn't return until after 11:00 PM) but it was a great experience and I'm happy with the results.

First, the test conditions:

I planned my route in Google Maps, with the "avoid motorways" option checked. I then modified the route to avoid A-roads as much as possible too, with the goal of keeping my speed below 50 (but at the same time not causing a traffic obstruction). I mostly succeeded in my goal of avoiding dual carriageways, and I never had more than 3-4 cars behind me (I pulled over a few times to let people pass), so I'm confident I caused no more obstruction than your standard caravan.The route was roughly as follows, though with quite a few detours to avoid busy roads:

I started the test by driving to my local Ionity station and charging from the current 68% to 100%. Don't worry, all six chargers were available the whole time so I wasn't being a pain! This both assured my battery was as full as possible, but also warmed the battery up nicely for the test.

The weather was "okay" for a range test - not ideal as the temperature never rose above 22C (72F), but not terrible, as there was no rain and minimal wind. The temperature was 13C (55F) when I started, and 7C (45F) (!) when I finished, so I'm very confident I could do even better on a proper summer day.

The test took nearly eighteen hours, fourteen of which were driving. I call it an "extreme" real-world test because 1) it was in the real-world, not a test track, but 2) no one in their right mind would drive the way I did for long. I had the aircon off the whole day, took everything out of the car I could (even floor mats!), and turned everything off I could, including al the driver aids and even the whole infotainment system.

Give us the results aleady!

When I finally pulled into my drive at 11:02 PM I had driven 356 miles, at an average speed of 25 mph and with an average efficiency of 4.8 mpkWh (~208 wh/mile for the Tesla drivers here).

I had 1% battery remaining, which translated to 4 miles:

I had done a poll on another forum before setting off, and received 34 incorrect responses:

Some thoughts on the test:

• Coming back through Oxfordshire and southern Northamptonshire was probably a mistake - I seriously underestimated how hilly that part of the UK is!
• Driving through central London was an absolute breeze, but driving through central Reading was a nightmare...
• The ID.4 seats are unbelievably comfortable. I could never have driven this long in my Zoe. My longest range test in that was around 10 hours and I was so very ready to get out of that car when I finished. Meanwhile, I got back in the ID.4 the next morning for another 200+ mile drive to Worcester and I was not bothered at all - it is so easy to drive and so comfortable to sit in.
• The GOM really is a GUESS-o-meter... I had times where the estimated range wouldn't change for 10 miles, then drop rapidly for the next 10. At the end of the test I drove over 15 miles with the GOM never moving from 45 miles indicated. I found doing the math of battery percentage to kWh multiplied by average efficiency to be spot on though.
• If I had done the entire test in London/Sussex I'm pretty sure I could have broken 400 miles - I swear I didn't break 30 mph from the time I first passed the M25 until I got to Oxford.
• I am glad I did this test, but I am never doing it again!

 

[Eric Nay]

Well, that's an interesting data point. With the way I drive (fast) I'm sure I will never reach this kind of range, but it is always interesting to see how this awesome car performs.

 

[JimmyVW]

Did you check your tire pressure before you left too?

 

[Ambassador Spock]

Did you check your tire pressure before you left too?

I did not, I should have slightly over-inflated my tyres though, good point!

 

[mochalatte]

Great test! That took dedication.

Did you have to adapt your route to add miles as you approached the end, or was your original plan about 356 miles?

 

[agzand]

That is an awesome data point to show what is possible under extreme conditions. However I wonder if this speed (25 mph) is the most economical? It is possible that a little bit of faster driving could result in better efficiency. It depends on the characteristics of the motor. In my BMW i3 I have seen very good range in low highway speeds. With iD4 I have not had a chance to test it yet.

 

[Ambassador Spock]

Great test! That took dedication.

Did you have to adapt your route to add miles as you approached the end, or was your original plan about 356 miles?

My original route was actually closer to 310 miles, so I ended up driving a longer way home and even then I had to drive to a nearby town and back to get down to 1%.

 

[Ambassador Spock]

That is an awesome data point to show what is possible under extreme conditions. However I wonder if this speed (25 mph) is the most economical? It is possible that a little bit of faster driving could result in better efficiency. It depends on the characteristics of the motor. In my BMW i3 I have seen very good range in low highway speeds. With iD4 I have not had a chance to test it yet.

My goal was to not got above 60, as I've seen my range drop steadily above that point. But, as I was on normal roads, there was a lot of stopping/starting - loads of roundabouts, for example. I spent quite a bit of time around 50 mph, but of course that was countered by plenty of time at stoplights/junctions, hence the 25 mph average.

 

[VW TECHNICIAN]

ID4 has very low internal resistance and low losses....and your motor ...inverter losses are 2.5%....but this could be higher because i can't see what was your regen numbers for this trip.To find out your motor efficiency table vs rotor speed ( ID4 speed of travel) ...you can preform multiple tests at flat terrain driving different types of speed. But from what you posted it is in the optimum efficiency table.
Tire pressure was only missing info on your test.
I run my at 42 PSI cold. Bridgestone

 

[Don]

That is an awesome data point to show what is possible under extreme conditions. However I wonder if this speed (25 mph) is the most economical? It is possible that a little bit of faster driving could result in better efficiency. It depends on the characteristics of the motor.

The biggest determining factor in EV range is almost always . . . . wind resistance - The faster you go, the bigger price you pay for punching a hole in the 1 bar of atmospheric pressure we're all surrounded with - This is why airliners flying at 40,000 feet can go much farther on a gallon of fuel than propeller powered planes which must fly lower 'in the soup'

It's pretty likely that if Spock had averaged 20 mph for the whole trip, he would have gone even farther. His average was 25 mph and that included all stops. His moving average was much higher, probably 35 or 40?? Reducing that would have given even more range

To ease any range anxiety you may be feeling on any trip, you just need to slow down - If it looks like you may not make it to your next charging opportunity, just slow down and you will. Within reason, your range can be pretty much what you need it to be if you manage your speed efficiently. Spock's trip proved that for sure - He went more than 100 miles farther than his EPA range rating

Don

 

[NightRiderFPV]

We need to hire a jockey to set the world record… lighter weight. Just think in five or ten years these range worries will be a thing of the past, or we will be living a Soylent Green nightmare. Fingers crossed.

 

[Don]

There are always range worries to some extent - Even in an ICE, when you need a gas station and you're too far away from the next one, but you could carry a jug of 'emergency fuel' and that's not an option for us

Don

 

[agzand]

The biggest determining factor in EV range is almost always . . . . wind resistance - The faster you go, the bigger price you pay for punching a hole in the 1 bar of atmospheric pressure we're all surrounded with - This is why airliners flying at 40,000 feet can go much farther on a gallon of fuel than propeller powered planes which must fly lower 'in the soup'

It's pretty likely that if Spock had averaged 20 mph for the whole trip, he would have gone even farther. His average was 25 mph and that included all stops. His moving average was much higher, probably 35 or 40?? Reducing that would have given even more range

To ease any range anxiety you may be feeling on any trip, you just need to slow down - If it looks like you may not make it to your next charging opportunity, just slow down and you will. Within reason, your range can be pretty much what you need it to be if you manage your speed efficiently. Spock's trip proved that for sure - He went more than 100 miles farther than his EPA range rating

Don

There is a difference between going 25 mph steady and doing 55 mph with multiple stops resulting in 25 mph. The first scenario is more efficient. The wind resistance is one factor, the other one is how efficient is the motor at that RPM. I have seen charts indicating motors are the most efficient between 25% and 75% of the maximum torque and they are actually very inefficient below 20% load. If you are driving too slow you could be outside of that range. Anyway I think there is a chance that you could do even better with a higher average speed (not higher top speed obviously).

 

[Don]

I have seen charts indicating motors are the most efficient between 25% and 75% of the maximum torque and they are actually very inefficient below 20% load.

Please post a link to that (those) chart(s) - That would be interesting

Most EV motors generate maximum torque right from zero RPM "The benefit of using an electric motor to power a car is that it can help drivers reach maximum torque from 0 RPM. This is because electric motors use an electric current, which moves through a magnetic field and creates the force necessary to rotate the armature and get the car moving. It’s a process that works pretty seamlessly, although one of the drawbacks to it is that it also creates when is called “back EMF”. Over time, back EMF slows down rotation, reducing torque. With no back EMF present when a car starts, it’s able to get out of the gate quickly, even if that high torque isn’t endlessly sustainable."

It would appear the efficiency drops off as the motor speeds up, due to Back EMF

Above from this article: How Electric Cars Achieve Instant Torque: An Overview for Grads of Mechanic Schools

Don

 

[agzand]

Please post a link to that (those) chart(s) - That would be interesting

Most EV motors generate maximum torque right from zero RPM "The benefit of using an electric motor to power a car is that it can help drivers reach maximum torque from 0 RPM. This is because electric motors use an electric current, which moves through a magnetic field and creates the force necessary to rotate the armature and get the car moving. It’s a process that works pretty seamlessly, although one of the drawbacks to it is that it also creates when is called “back EMF”. Over time, back EMF slows down rotation, reducing torque. With no back EMF present when a car starts, it’s able to get out of the gate quickly, even if that high torque isn’t endlessly sustainable."

It would appear the efficiency drops off as the motor speeds up, due to Back EMF

Above from this article: How Electric Cars Achieve Instant Torque: An Overview for Grads of Mechanic Schools

Don

We are talking about efficiency not torque. Here are a couple of links:

https://www.energy.gov/sites/prod/files/2014/04/f15/10097517.pdf

https://x-engineer.org/automotive-engineering/vehicle/electric-vehicles/ev-design-electric-motors/

https://cdn.borgwarner.com/docs/def...150-sheet-euro-pr-3-16.pdf?sfvrsn=a642cd3c_11

This image from the second reference sums it up. This is Borg-Warner HVH410 electric motor efficiency chart:

 

[SunWizard]

Here is a good chart for a motor that is more similar to our ID.4 (since that Borg is a 700V 2000Nm torque monster):

From:

Synchronous Reluctance motor_03 - Electric Motor Engineering

3. Efficiency map of the SynRM

www.electricmotorengineering.com

 

[Andy at Ross-Tech.com]

Neat! It looks like peak efficiency can be had at moderate load between say 7k and 10k rpm, which in an ID.4 works out to about 45-60mph.

 

[SunWizard]

I like this topic so I searched more and found the curve for the Nissan Leaf which is older tech + similar torque (254 vs.310Nm RWD) and lower power (147 hp versus our RWD at 200hp or AWD at 300hp) but similar RPM as the ID.4 from a good Oakridge national lab study:

 

[Don]

The efficiency of the motor changes only a few percentage points between about 4Krpm and 10K. But the power required to more the car through the air rises with the cube of the speed

Cd is the drag coefficient (that is, a fudge factor, that depends on the shape of the car)
A is the frontal area of the car
ρ = 1.20 kg/m3 is the density of air
v is the speed of the car.
If you look at the equation above, at standstill (v=0), there is no air resistance. But once you're moving the power rises rapidly, as the speed cubed. This means that in order to go 50mph on a country road, your engine has to put out 8 times the power it does as when puttering around town at 25mpg, just to deal with the drag.

The motor may gain a bit of efficiency as you speed up, but the power required to move the car goes up by lots more than the motors gain in efficiency - 8 times more power at 50 than at 25, so speeding up is still a losing proposition if you're trying to get the max range from an EV

Don

 

[Don]

Another formula I found tells you how much faster you can go when you double the power. Multiply your current speed by 1.26 and you've doubled the required power, so for 25 mph, it takes double the power to go 31.5 mph

Don