Searching for a “Range Anxiety” Scapegoat

By · May 31, 2011

LEAF SOC

Seven bars and 64 miles. How these indicators translate into real-world range is far from certain.

I wanted to blame Nissan. For all the glories of the Nissan LEAF—which I’ve been enamored with since making it my daily ride three weeks ago—the company made a fatal flaw in its dashboard display of existing range left in the all-electric car’s battery. That’s how I felt last week after what I had assumed would be a routine trip last week from Berkeley to see friends in San Francisco and nearby Daly City.

I backed out of the driveway in the morning with 102 miles of estimated range, according to the car’s computer estimates. The number of estimated miles, and twelve bars representing the level of state-of-charge, are the two pieces of information the Nissan LEAF provides drivers to indicate how far the fully charged 24 kWh battery can safely go until it needs to get plugged in again.

As we’ve discussed on this site, what EV drivers want most is a plain-and-simple percentage number for the State-of-Charge (SOC) of the battery. With a percentage number, and an awareness of past efficiency—probably about 3.3 or 3.4 miles per kilowatt-hour—you can get a decent idea of how much range is remaining.

Instead, the on-board computer takes a guess at remaining mileage. That number is simply too erratic to be useful. The number jumps up and down by five or 10 miles, depending on how you’re driving at the moment, if you have the AC on, or if you’re using Drive or Eco modes. The computer obviously doesn’t know if you’ll continue to drive in the same fashion, but it tries nonetheless to give you an approximation of the remaining range. It doesn’t take long behind the wheel of LEAF to stop putting much faith in that number, especially during the early part of a trip when there’s a lot of juice.

Driving by Numbers

So, I took off on the first leg of my trip, to downtown San Francisco, about 12 miles away, to meet a friend for a cup of coffee. No problem. Then, I traveled another 15 miles to Daly City, just south of San Francisco. I was keen to show off my LEAF to my pal, who is contemplating buying an electric car. He suggested a restaurant all the way back in downtown San Francisco—essentially doubling back another 15 miles. The ride back into town was a chance to demonstrate the LEAF’s quick acceleration in D mode, with the AC keeping us cool. All my attention was focused on the driving experience, and just 45 or so miles into trip, range was not on my mind.

Again, the fact that the estimated range showed 60 miles or 50 miles or whatever didn’t matter—because that number jumps all over the place. The last thing you want to do behind the wheel is to start tallying numbers. Besides, as soon as you slip into Eco mode and turn the air off, you get the indication that there’s plenty of juice left for the day of driving.

The 12 "state of charge" bars—while less erratic—also seem symbolic, because with about half of them left, I should have had about half the battery left. With an estimate of 90 or 100 miles at the beginning of the day (and a consistent driving style), I shouldn't be the least bit worried about range.

Daly City to Berkeley

It's easy enough to measure distance between Point A and Point B. It's a lot harder to measure the amount of energy left in a battery.

Getting Anxious

Things quickly changed. After lunch, we headed back to Daly City, which is moving in the opposite direction from home. I needed to get there and back home in about an hour to pick up my kids from school—as I had promised my wife I would. In the short time on the faster highway route back to Daly City—zooming along at about 65 mph along with the traffic—the symbolic nature of the estimated range and the twelve bars got extremely real, extremely fast.

By the time we reached his house, it took me by surprise that I was down to three bars and an estimated 15 miles of range for a 20-mile trip home (according to the nav system). How did it shift so fast? Was that a real number? Even though I was pretty sure the LEAF was underestimating the range left, I had no way to tell for sure. My only choice was to stop, take a trickle charge for at least an hour, and pick up another five (insurance) miles. I also had to call me wife to explain that she needed to interrupt her appointment to pick up the kids. The experience turned my range anxiety into the much more dangerous variety: marital anxiety.

An hour-and-a-half of 120-volt charging later, with 22 miles of estimate range and four bars, I prayed to the EV spirits and took off for home—with AC off and in Eco mode.

Then, the fortunes of battery state-of-charge changed again. After only a half-mile of slightly downhill driving to the highway, I was up to an estimated 26 miles of range. On the steady ride home through congested rush-hour traffic, that number barely budged—and only until the last three miles of the 20 mile journey did it drop down to 16 miles and three bars.

What?! If I really only had 22 miles, I should have been down to a single bar and two or three miles of range left—but I still at 16 and three bars. What was underestimated back in Daly City was now either accurate or overestimated—but regardless, the dashboard information only served to induce range anxiety, instead of dispelling it.

Who’s to Blame?

I still want to bust Nissan’s chops for not providing that SOC meter in a single percentage number. C’mon, why not trust me with that number? But after further study, I don’t think it’s so simple. After speaking with a few battery experts, I now know that it’s tricky to measure SOC. It’s not like putting a gauge on gasoline sloshing around a gas tank. Any number of factors makes it difficult to know for sure how many miles or real-world miles are left for a driver. Maybe Nissan was watching my back, by compelling me to charge up a bit, to prevent me from getting stuck on the roadside.

My best guess is that I never really needed to stop to plug in before taking off on the trip back home. I’m almost positive that I could have picked up the kids as I promised. The problem wasn’t that the 24 kWh pack lacked sufficient range for my day of driving. It was a measurement and communication problem.

There's a tremendous national effort underway to extend the capabilities of today’s battery technology. Now, I’m wondering if a big chunk of those resources should be put into better systems for letting drivers (and their spouses) know what’s already there and waiting to be used. There's no sense in blaming the car companies, the battery technology, or the driver for a lack-of-range problem that might not exist in the first place.

Comments

· · 3 years ago

I never look at the "remaining miles" on my MINI-E. The car can't possibly know how far I can go. It doesn't know if I'm going up a long steep incline, It doesn't know if I'm going to be driving 80% of my trip on the highway, it doesn't know if it's going to be 95 and humid and I'll be using the A/C the whole time and it certainly doesn't know if I'll be feathering the accelerator to extend the range or stomping on it to get to where I'm going in a hurry because I'm running late.

With a simply SOC displayed in a numeric percentage, I know exactly how far I can go and under what conditions. It took me a few months to learn that, but after some time with the car I can tell how far I can go plus or minus 5 miles under any conditions.

It's one of the things I strongly voiced my opinion to BMW. As part of the MINI-E trial, I was encouraged to offer opinions as to what I would like to see on future BMW electrics and a clear numeric state of charge was at the top of my list, along with aggressive right pedal regen. They listened because I'm told they are incorporating both in the ActiveE and i3.

Brad: I hope you have some time to drive the MINI-E when you come out East in a few weeks. It's yours for the taking.

· Rob Fiedler (not verified) · 3 years ago

Hi Brad. I had a very similar experience here in SoCal with my Leaf SL-e. My first round trip to Hollywood from San Pedro (approx 65 miles round trip) was nerve-racking when the 65 mile per hour freeway took more energy bars than I expected. I had checked with Hollywood Toyota to confirm they had a EV charging station. The manager said they did, did not know if it would work with my Leaf, but said I could try. When I got there the charging station was locked up in the service bay and the manager said he did not have the key. I went over the hill to Universal Nissan and they were very helpful. They allowed me to charge with their J1772. After an hour I went on my way. I probably could have made it back to San Pedro without the booster charge, but having it made me feel safer. What we need is more charging stations. And those who have them, like the LA CAr Guys at Hollywood Toyota to make them available on weekends.
Thanks for all you great posts.
Rob

· · 3 years ago

Welcome aboard. As I discussed with you back in December (http://www.plugincars.com/ev-expert-says-nissan-leaf-dashboard-lacks-mos...), the lack of a simple percentage of battery remaining number is a big mistake. Their system actually creates range anxiety, as you found out. As difficult as your battery expert says it is to come up with an accurate SOC, that number exists and can be extracted from the car with a diagnostic tool. It was a decision not to share that information. Had Nissan (or GM for that matter) listened to actual EV drivers' advice, a prominent spot on the dash would give you a 100.0% when you unplug in the morning. When you pull in to work, perhaps you find you've driven 24.8 miles and the SOC reads 71.2%. You know it's taken 28.8% to drive those 24.8 miles. Something to compare with tomorrow's numbers. Or to strive to better. Anyway, it's a baseline. If the SOC isn't as reliable as it is on my RAV4 EV, and it doesn't drop linearly, you'll be able to discover that as you find it takes more or less charge to drive when the battery is more or less full. But that damn guessometer is all but useless.

· cdub (not verified) · 3 years ago

The reason it said 15 miles of range was because it thought you'd continue to drive 65 on the freeway - and then it's probably be right... but you said you drove in stop and go traffic - which is way different than driving 65 so of course that changed. Going over 60 seriously depletes range quickly.

· David Kirsch (not verified) · 3 years ago

Sorry guys... I don't think you can blame this one on the display. These are limited range vehicles. Straight SOC display would not change that fact. Everyone who's ever used a laptop battery with an SOC display knows that SOC can jump all over the place just like "range". Bottom line: only people who are willing to deal with these types of anxieties -- range and / or marital -- should consider purchasing an electric vehicle.

· · 3 years ago

David: I love to get opinions like yours that come from first hand experience. How long have you been driving an electric car?

· · 3 years ago

My fifth generation Th!nk City EV has a very reliable state of charge meter, no jumping around. I agree, a "miles remaining" gauge is only good for making the driver nervous, so I am glad Th!nk did not put one in. But then again, Th!nk has been in the EV business for about 19 years longer than Nissan, so it is expected they might get it right.

After watching BMW go through two generations of research vehicles (the Mini E being the first) before attempting to sell an EV, and Mercedes doing the same with the Smart ED, as well as several other manufacturers like Volvo, I wonder if the Leaf can really be considered anything more than another research vehicle? The more I hear about the Leaf, the more it sounds like a research project. A very nice research project, maybe better than the Mini E in a lot of ways (except for a pathetic built in charger), but a research project none the less.

· Tom K (not verified) · 3 years ago

I've put 1579 miles on my LEAF all over socal since I got it three weeks ago (67 mile trip from the dealer) and I've grown accustom to the instrument panel display like most new owners. I use the numerical display for amusement and the bars for a more real world indication of juice remaining. After all, you've gotta know your limitations...

· · 3 years ago

As you mentioned, the range calculation can be misleading because it is based on past driving behavior. It would help enormously if the LEAF displayed two range numbers based on 'expected future driving', i.e, one number showing expected range driving @30 MPH and one number @60 MPH. Then you could better estimate your range depending on whether you are planning on mostly freeway or local streets.

· · 3 years ago

I think your last guess was the correct one, Brad. The Leaf is probably gauged in a way that it lets you go a few extra miles beyond when the display hits "E." Frustrating, to be sure, But you'll probably have to run out of power completely one day to get a feel for just where it really stands.

I use digital audio recording gear in my work and one of the first things you learn is that you are not supposed to let the meters overload, as digital audio distortion is truly horrendous sounding. Manufacturers know, however, that most recording engineers will be inclined to occasionally venture into this danger "red" zone. So, they purposely calibrate their machines to lie to the engineers . . . telling them that they are "in the red" when, in fact, they've got a little extra headroom to play with. Even though you don't have "true" metering, it's preferable to have the recording deck "lie" to you instead of possibly ruining a good recording.

Getting back to cars, my '51 Chevy had a sticky gas gauge. When the tank got about to 1/8th full, the gauge would tell be it was empty upon starting up. To get a more accurate reading, I'd simple tap on the display a couple of times with my index finger. If there really was some fuel left in there, the needle would invariable move a notch.

So, yeah . . . try tapping on the display a couple of times with your index finger. :-)

· · 3 years ago

Three weeks into the car, I admit that I'm a novice. I'm sure I'll start to figure out what the estimate/bars is trying to tell me, but until I work my way up the learning curve, it's going to be a challenge, especially when the SOC is getting anywhere the distance I need to travel to get to a plug.

My main message is that OEMs need to listen to the experienced EV drivers, and do a TON more study of the issue of how to measure SOC and communicate it in multiple, overlapping useful ways--so folks can know with a much greater degree of certainty if they need to stop and charge or not.

· · 3 years ago

Not to be a wet blanket, as I'm a huge EV fan, but the jargon being thrown around here about SOC, etc. is exactly why, as much as I want to see EVs stomp ICEs as quickly as possible, it's unlikely to happen as soon as some of us wish it would. The average consumer isn't going to be, or want to be, as "techie" as the early adopters here. Just another thing that OEMs are having to deal with on this issue, and others, having to do with producing, and selling, EVs.

· Nick F (not verified) · 3 years ago

The car has a sat nav. There are accurate maps Nissan can buy showing the gradient of each road. Nissan can run the car on a rolling road and on a test track at different speeds, in different air temperatures and make a table of energy consumption for each possible scenario. ...So why didn't they make it so the driver to tells the car where on the map they are going and the route they are taking and the speeds they want to go for each road type? That way it wouldn't be that hard for the car to make a half decent guess at how much juice will be in the battery at the end. The car has cruise mode right? ...So it's not like your going to go down the road trying to do 50mph, but then accidentally doing 56mph.

· · 3 years ago

Ok, you want a SOC % ? "turbo2ltr" of MNL will offer one, if there is enough interest ;-)

BTW, with the new firmware, Leaf range is conservative. If you strictly go by the RTE, you won't run out of charge.

Estimating the range left is going to be an important task for the future. All the information needed to get that number is available to Leaf, once you enter a destination - the route, elevation, speed, traffic and your driving behavior. Nissan should use all this info and get a good range estimate.

· Nick F (not verified) · 3 years ago

......i know it's more complicated than that, I'm just saying they should be able to get a better approximate estimate.

· · 3 years ago

OK, so let's not call it SOC. We could call it "fuel gage." doesn't matter. What I don't understand - and what Marc has challenged - is the concept that it is hard to determine accurate SOC. Toyota could do it in 1996... is it harder today? The Rav4EV has tremendously accurate SOC...er... fuel gage.

Really, I don't get it. Battery experts or not - we have many millions of miles of experience in a car that accurately reports SOC. It just can't be that difficult.

· · 3 years ago

@Darell - Can you describe with some detail how Rav4EV range is displayed/communicated, and how that plays itself out in terms of the driving experience? Do we have a successful model to follow? And if so, why aren't the OEMs following it?

· JJJJJJ (not verified) · 3 years ago

Nick makes a great point. GPS + traffic updates should be able to let the car tell you if youll make it or not.

Oh and also, no range anxiety on BART. It seems like your trip could have been easier and street free on BART.

· Priusmaniac (not verified) · 3 years ago

There should be a better way to assess the state of charge of a battery. A special electrode thickness, or a chemical change or an electrical property. Alternatively, they should sequence battery use. Dividing it in ten sections and using up completely one section before starting to use the next one. In this way we would know for sure how many full sections are left. Problem is that all the ten sections are probably needed simultaneously to provide the needed power, but perhaps it isn’t so.

· · 3 years ago

To qualify what I say, I've never driven an EV (although my Nissan Altima Hybrid has a miles range left option in the display and I've seen that number jump around, too).

Nonetheless, I think asking for a percentage of SOC in this situation is easy because the range is 100 miles. Taking the percentage of the 100 mile range is easy math. What happens when the next generation comes out with a range of 135 miles? Less easy math. As the article stated, the last thing that you want to do is start tallying numbers behind the wheel.

I'm not saying that I have the easy solution. I just think that we should be careful for what we ask for. Quick, 58% of 135 miles is? In the end, if you're simply going to come up with an estimate in your head, then you've lost the advantage of getting the car to display something as accurate as 58%.

· 54mpg (not verified) · 3 years ago

The solution may be is to provide a reserve battery with around 20 miles of range. The main battery has the range of around 100 miles. Once that is dead, the driver stops the vehicle and switches on the reserve battery.

· George Parrott (not verified) · 3 years ago

Brad, et al,

What seems to be missing here is that while Nissan cannot seem to get their EV range display to work in a stable and functional manner for actual driver use, GM has done a superb job with the EV range projection on their Chevy Volt.

We have both the 2011 Leaf and the 2011 Chevy Volt for our two career, two car family, and we use them daily. We NEVER get stable range displays on the Leaf, e.g. in the first mile from our house we almost always lose up to 3 or even 4 miles of digital range display, and using the heater or getting on the freeway with the Leaf produces BIG DROPS in the range.

However with our Volt, NONE OF THOSE ERRATIC shifts of range occurs. Over the first 5 miles from the house we are usually still "spot on" for actual and predicted range, and freeway driving typically produces MAYBE a drop of less than 5% between startup prediction and ultimate miles to the kickin for the ICE. In five months of living with the Volt, we have gotten actual EV range of less than the predicted startup perhaps 3 times and MORE EV RANGE than the startup projection ....by 1-2 miles about 80% of the time.

GM has their range projection algorithm totally "dialed in" after all those months of fully testing the whole drivetrain and platform, while Nissan....appears as lost in the EV range projection as their GPS maps in the navigation system--which are 5 years OUT OF DATE for our area of W. Sacramento and which could not find a downtown restaurant we tried to go to last weekend, and that restaurant has been in the same location for WELL OVER 5 years !

· Philaphonic (not verified) · 3 years ago

I don't know how hard it is to estimate the SOC, but I do know it is possible. For my 2002 Prius, I bought a "Prius mini-scanner" from Graham Davies at www.ecrostech.com that plugs into the car's diagnostic port. It displays, among other things, the traction battery's SOC to 1/2 % accuracy. There should be no reason why this can't be done for the Leaf as well.

· · 3 years ago

From Ford's website it appears that the Ford Focus Electric will use a more % based SOC with a battery that goes down as battery charge does
I tried to post the url but Spam Filter won't allow it....
ford.com -> Hybrids & EVs -> Focus Electric -> Brake Coach

From what I remember from Physics the energy remaining in the battery is measured by measuring the voltage and comparing it to the known voltage when the battery is fully charged and when the battery is discharged which should be more or less equal for the size of battery we are discussing (24kwh). It will of course change any part of the battery makeup changes.

I'm thinking an equation like this:
SOC = 2 * Vc / (Vmax + Vmin)

SOC State of Charge
Vc Current voltage
Vmax Known voltage when the battery is fully charged
Vmin Known voltage when the battery reaches the shutoff point

P.S. It's been 5 years since my last college phys class so anyone correct me if i'm wrong

· · 3 years ago

Doh bad equation...try this

SoC = (Vc - Vmin) / (Vmax - Vmin)

· · 3 years ago

Overall I find the SOC meter on my MINI-E to be very accurate with one exception and that would be while driving on the highway for a while, the SOC will display slightly less than what it's true reading would be. Once you slow down for about a minute, it can read the correct SOC and then the gauge creeps up to the proper reading.

For instance, if I'm driving for 20 minuets or so at 70 mph, the meter may read 60% SOC and then I get off the highway and sit at a red light for a minute and it bounces up to about 65% which is the true SOC reading. Knowing that, when I'm driving at highway speeds I know I usually have about 3%-5% more than the SOC reads. However, driving at 40mph and under, the meter is pretty much dead on. The good thing about it is if it ever is slightly off, it's always under-estimating the SOC, never over estimating. If you are ever concerned and need a precise reading because you are really pushing the limit, all you need to do is stop the car for less than a minute and it will correct itself to the exact reading.

Another thing I like about this car is that when the SOC and estimated range reads 0, I can still drive 10-20 miles depending on the temperature. I frequently use this cushion. It's like zeroing out your checking account when you really have $100 in there. It gives you a cushion, just in case.

· · 3 years ago

@Tom

If the Mini-E uses the voltage for measurments it would make sense that the reading would drop whil driving for a long time on the highway. If I remember from your previous posts the Mini-E uses a fan to cool the battery? If that's the case the batttery still heats up. If the battery gets too hot the current voltage reading will drop.

A dumb measuring device will not remember any previous readings and will only use the current voltage.

A possible solution may be to weight the readings acording to time taken.
Example: Battery voltage readings are 9v, 8.9v, 8.8v, 8.7v, 8.2v
A dumb meter would say, current charge is 8.2v so charge is 92%
A smart meter would say, current charge is 8.2v but i know previously it was around 8.9 to 8.7. I'll average to 8.5 and say 95%.
If the next measurment is 8.5v, the smart meter would stay at 95% whereas the dumb meter would jump from 92% to 95%

· · 3 years ago

For starters, I would definitely like to see the SOC% displayed.

Nick and EVnow make great points. The Leaf has a lot of data available to make a more accurate range prediction, Destination, route, speed limits, elevation, traffic, and driving behavior. Hopefully they made the software easy to update.

There are lots of variables though and guessing the range is a very complex and interesting software problem. Such a system would benefit from being able to learn from the results of its previous estimates.

I do feel "iffy" about a car knowing too much about my driving habits, but that ship sailed long ago.

· · 3 years ago

What if the center display for EVs was built on an existing mobile OS such as iOS or Android? It would practically be a built in iPad.

3rd party developers would be able to build apps for your car as easily as they build apps for your phone. You could have competing apps for a navigation system that calculates range or best path differently. Apps for music, hands-free voice calls, etc.

It standardizes the platform for APIs to the car, a relatively new concept, into something familiar that already exists.

· · 3 years ago

>> @Darell - Can you describe with some detail how Rav4EV range is displayed/communicated, and how that plays itself out in terms of the driving experience? Do we have a successful model to follow? And if so, why aren't the OEMs following it?<<

I wish there was a successful model to follow! The Rav - like all other cars - came from the factory with a fuel gage. It looks like this:
http://evnut.com/images/rav4/rav_dash_led/rav_cluster01.jpg
If you count all segments and hash marks you can convince yourself that there are ten segments to work with. So with a 100 mile car, that's at least easy math. But it still pretty much sucks.

So if it doesn't come from the factory with the right stuff, you fix it! One of our drivers developed a reader for the OBD2 port, so we have all information that the car knows. And the car knows the SOC very accurately! We display it digitally to within 0.1%!

Here is what the Palm device looks like that displays the OBD2 info:
http://evnut.com/images/rav4/rav4info_gps/rav_palm_front.jpg
I'm at 76.0% SOC, and using 3A (likely with my foot on the brake.)

So no - none of the OEMs have done it right. My point is that the information is THERE... the OEMs just won't show it to us because we're not worthy. There is definitely a thought out there that drivers should be protected from such scary information. Idiot lights rule! "Check Engine" anybody?

· Christopher (not verified) · 3 years ago

I've had a LEAF for almost a month now and I don't know how unpredictable the range display was before the update, but I find its estimation to be pretty reasonable. Yes, it is anxiety-inducing to see it drop off as you go to freeway speeds, use the heater or A/C, or do an extended hill climb, but that's appropriate as that is what is actually happening to your remaining range. You need to know that you can't keep up that current level of energy consumption. Of course, the opposite occurs as well as you get into slower moving traffic or descend that hill (woohoo! regen!) and your range looks better and better... that also is appropriate. Unfortunately, you can get "range complacency" if you don't realize that your return trip isn't going to have the same energy-sipping circumstances.

Regarding the "SOC", the battery charge level is displayed right next to the range estimate much like an analog gas fuel gauge (also not in a percentage) so I don't understand what the kerfuffle is about. I suppose Nissan should just make people happy and allow switching between charge percentage and range estimate to make this complaint go away. (Yes, estimating charge is difficult and varies with temperature and over the life-of-the-battery and for different battery chemistries. So a precise percentage won't be very accurate, but so be it.)

My thought is that all of this just due to having to budget driving within the range of 24 kWh battery. In other words, not great but still a useful limited range of 65-125 miles depending on conditions. Once our electric vehicles are capable of double or triple this range, it'll be rare that most people have to worry about their current range remaining at all. In other words, it'll only get better!

· Christopher (not verified) · 3 years ago

Oh, I wanted to add that the fascinating thing about driving the LEAF is realizing that these large swings in energy consumption at different driving speeds were just as present with our gas-burning cars. Even with dynamic mileage estimates (like in my old Audi A3), we didn't pay as much attention -- I think merely because of the larger range available at the faster "recharge" at the pump.

Again, more range on these vehicles (and perhaps access to level 3 charging) will ease the unease. This is the early adopter phase. In the meantime, I'm enjoying the heck out of my nifty electric car!

· · 3 years ago

@Christopher

I haven't tested this, but I think that gas cars have a more stable range at different speeds than electric cars. The reason is the gas car's inefficiency. With gas, you're paying a much higher energy overhead regardless of speed.

· Charles Whalen (not verified) · 3 years ago

Estimating SOC for a lithium-ion battery pack in an EV is a very difficult, complex mathematical problem which involves solving systems of non-linear differential equations. Using Fast Fourier Transforms is not a practical solution due to the computational requirements of doing this on the fly, in real time, in a car. Approximations to solutions include adaptive filtering, such as Kalman filters, or using systems of linear differential equations to approximate the non-linear differential equations and then using standard eigenvalue/eigenvector techniques.

The world’s leading battery engineer in this particular specialty, in developing such mathematical solutions to the lithium-ion battery pack SOC estimation problem in an EV, is Dr. Mark Verbrugge of GM. Verbrugge and GM hold the leading patents in this field and are far ahead of other automakers. Nissan is a bit behind the curve in this area and is playing catch-up. They’re working on it; it’s a work in progress.

· · 3 years ago

Brad, to George's and Charles' points above, how do you think the estimated miles of the Leaf compared with the Volt? I am consistently amazed how accurate the Volt's estimated miles are for me. It's almost always accurate to within 1-2 miles (unless I'm doing 80 mph, blasting the AC and have the wipers on).

· · 3 years ago

This is what you are staring at when driving the MINI-E: http://1.bp.blogspot.com/-e3fhky6um8s/TdwwrDKX2FI/AAAAAAAAAqo/vOgD9kg_PK...
The large gauge is the SOC, you can't help but look at it. It is where you would normally find a speedometer, directly in front of the driver. You can also see the digital readout of 15% on the bottom. That is what I had it set at, the SOC %, so I have the big analog gauge and the digital readout of the SOC. I can toggle the digital readout to display SOC, estimated range, battery temperature or amp hours used for 100 miles. I usually either leave the soc% or the amp hours used there, never the estimated miles and I'll quickly toggle to battery temp but won't leave it set on it.

This photo was taken three weeks ago after I just completed a 100.1 mile trip and still had 15% SOC remaining. I could have easily driven 130 miles that day.

· · 3 years ago

I've owned my Leaf just since May 11, but thanks to MNL forum members and discussions, I had the info about ignoring the Guess-O-Meter and primarily using the 12-bars indicator, and then simply learning my local terrain here in hilly San Diego county.

But it's hard to explain this to my wife, and as was previously posted above, this simply isn't going to work for your average driver, and they'd likely get in trouble fast.

Now, if only ECOtality would fulfill its promise of actually installing public charging stations, driving anxiety would not be any different than for an ICE.

· · 3 years ago

To be predictive, the miles remaining calculation needs to look at the GPS path you enter, along with weather, elevation, and traffic data, to actually predict your range with some precision. Until then, a useless gauge.

LEAF needs a %SOC meter and a 6.6kW charger. EV Project needs to install promised infrastructure because plans change.

· · 3 years ago

Even if we can't get exact on the LEAF, can we establish rules of thumb? Like one bar equals about 7 miles, when driving in Eco with no AC? Or one bar equals about 5 miles in D with AC? Maybe with fudge factors for highway versus city. I don't know, but it would be handy to have some rough guideposts.

· · 3 years ago

See what's odd here is that every Rav driver knows that it is possible to get 10 miles per 10% (one segment) on the fuel gage. Yes you can burn through the battery faster, and yes you can make the charge last longer, but no matter what - you CAN manage one mile per SOC percentage. It might mean you turn the AC off or drive slower - none of these items has yet killed a driver. So that 1:1 has forever been the easy benchmark. It isn't written in stone, and it isn't variable - and it is one benchmark that everybody can work around. If you notice that you've got 23% SOC remaining, you know for SURE that you can get at least 23 miles down the road if you need to. And more if you REALLY need to. And as we've never had a range-o-meter on the car... hey! Nobody has gotten stranded.

· JJ - Can (not verified) · 3 years ago

Darelldd... about the check engine light... you're right, it should display the trouble code on the dash of ICE cars, instead of having to go to a garage.

· · 3 years ago

Brad, I suggest you come over and we take a ride in my RAV4 EV and you watch the RAV4 Info in operation. You'll get it. As Darrel mentioned, the information is already in the LEAF. Plug in a diagnostic tool and you can get the battery state of charge (SOC.) It'll read 23.4% or whatever. Nissan and in fact every automaker who ever made an EV has refused to put that number on the dash. Why? Because they think experienced EV drivers who ask for it are ipso facto atypical, not regular consumers, because after all we've been driving EVs. What's freakier than that! And they've come to trust the "experts" they've long consulted and believe asking focus groups of "normal" consumers will yield valuable information. It doesn't. Apple never went to focus groups or experts to gauge the demand for the iPod. They made it the way they did because they believed in it.

· · 3 years ago

@brad "Even if we can't get exact on the LEAF, can we establish rules of thumb?"

Here is your thumb rule.

Reset the Leaf miles/kwh on the console after recharging. Also reset the trip miles.

At any point in the trip,

Kwh left = 22 - (miles driven / miles per kwh)

Range left = Kwh left * miles per kwh

Ofcourse, this assumes 100% charging and that you will drive the same way you have been driving in this trip. If you did 80% charging, subtract 5 kwh.

Let us take an example. You have driven 50 miles and your Leaf says 4 m/kwh.

Kwh left = 22 - (50 / 4) ~ 10 kwh

Range Left = 10 * 4 = 40 Miles.

Well, may be a small mobile app would help you with the calculation.

I'd actually go with the range being shown (may be + 5 miles).

· Charles Whalen (not verified) · 3 years ago

In order to see SOC on the Volt, you have to pay $550 a year to subscribe to GM’s GDS2 software. That’s on top of paying $3,600 upfront to make the required purchase of a pair of Bosch GM MDI devices.

While I am mighty impressed with GM’s engineering prowess and accomplishments in the Volt, I have to say, however, that I think GM is making a mistake in the way they’re discriminating and segregating their customers into two separate groups -- 1) the vast majority, making up the mainstream customers, whom they are treating as technically challenged and illiterate, unable to comprehend the most basic battery concepts and measures, such as SOC, with GM wanting to keep this group of the vast majority of their customers in the dark, hide the technology from them and keep it all as a black box, knowing that very few would be willing to spend an extra $3,600 upfront plus $550 a year to access this information; and 2) an elite group of technically-savvy, hard-core EV experts, for whom the battery technical data is important enough that these few people are willing to fork over the extra cash to access it.

Creating these kind of segregated class divisions within the EV community, into an elite, technically-savvy cognoscenti on the one hand, and the ignorant, uneducated, unwashed masses on the other hand, does a disservice to the cause of widespread dissemination and promulgation of EV knowledge and education, adoption and commercialization, and democratization and empowerment. It goes against, and flies in the face of, the fundamental principles and values of the EV community and everything it stands for. It also doesn’t inspire confidence in GM and makes them look as if they’re not completely confident in their technology and don’t think it’s quite ready for primetime. I, for one, have plenty of confidence in GM’s technology, based on what I know, but the problem is one of appearances and perception for GM, in that they are not projecting that confidence to the customer by the way that they are deliberately trying to hide from the customer the most fundamental EV and battery data that characterize any and all EVs at the most basic level and make them what they are.

· WishboneAsh (not verified) · 3 years ago

An energy flow meter would help determine range perhaps better than voltage measurements alone. This is similar to what is done in aircraft to calculate remaining range since the fuel tanks in small planes are only accurate when full or empty! Some factor needs to go in to account for battery age/temperature etc so total charge may change over time, but the concept should be much better than this predictive technology.

· · 3 years ago

Sorry I'm late for this thread -- I hope Nissan (and GM) are reading! I can add two more points.
First, I haven't had an opportunity to check if the software update changed this, though it would surprise me if it had. What happens when you get down to about 6 miles' remaining range on the Nissan Leaf display? The numbers disappear completely, and you're left with a bunch of dashes! That's not helpful... (The same thing happens on the Volt, but without the same level of anxiety.)

Second, the only way you can tell how far you've traveled since your last full charge is to manually reset the B odometer -- an elementary oversight!
It's not too late for automakers to start paying attention to discussions like this, and to invite plug-in car owners and Silicon Valley's experts in usability and human-computer interfaces to help upgrade the software.
-- Felix Kramer, Founder, CalCars.org

· Ed Marek (not verified) · 3 years ago

If you want a "scapegoat" for LEAF range anxiety, I'd suggest you look not at the range and SOC indicators, or any other aspect of the car. Mr. Berman's problem appears to me to be that he changed his travel plans, requiring a recharge, and he (like every other LEAF owner in California) found the public infrastructure to be inadequate.

The LEAF is designed to allow fast DC charging precisely for this situation. The vast majority of California LEAF's are equipped with this option, and California probably has the largest DC charge capable EV fleet in the world, other than Japan, but NO operable DC charge stations.

I am a LEAF owner in far North California. I drove my car home from the bay area, about 245 miles, on the currently available L2 infrastructure. It was time consuming, of course, to recharge, but, the 12 bar SOC charge indicator was, and since then has continued to be, quite useful. My biggest complaint is that Nissan seems to have re-calibrated the bars to make them LESS exact, and add a "hidden reserve" to meet the expectations of American drivers.

I knew the range indicator would be nearly useless to me before I bought the car. I live on a hill, and the 50-something mile range when I leave home with an 80% (10 bar)charge, increases to 100-something miles after I descend 1500 feet in the first six miles.

The best use I've made of the range indicator is as a "speed nanny" on long flat drives. From Davis to Chico I was able to deduct the miles remaining in my 90 mile trip, from the range estimate, and drive slowly enough to maintain about a 20 mile "reserve". When it was clear I would make it, I sped up (to almost 60 mph...) and arrived at my recharge point with an indicated two bars and 13 miles remaining.

· Bill from Mesa AZ (not verified) · 3 years ago

I took possession of my Leaf 36 hours ago. It was fully charged at the dealership. After driving 20 miles home I plugged in the wall charger, a Blink from the EV Project. The next morning the range indicator showed 107 miles. My wife and I commuted together and went to my son's house for a total of 84 miles of which about 24 miles were at 65 mph. The indicator had 16 miles remaining. Even shallow grades can be used to regenerate a lot of miles. There was an large difference in how fast the range dropped on the highway, to be expected. About half of the charge was used on the highway. The A/C was on as the local temps were in the 90s. Night driving on the highway too. This morning's full charge shows 88 miles. I'll see what happens from here. Oh, my gas guzzler is a Prius.

· · 3 years ago

If you curious about what Porsche is thinking about range estimation, check out their latest patent application here:
http://evtechpatents.com/?p=79#more-79

In short, they want to allow speed, acceleration, AC limits but also use the GPS system to take into account elevation, road speed, weather, etc.

· Bill from Mesa AZ (not verified) · 3 years ago

My dealer replied to the miles remaining query as follows. "the Leaf averages the miles driven per charge and posts that as the miles remaining". Indeed as I drove today the miles remaining rose to 98 in less than two miles driven. My intent is to charge to 80% and monitor the battery charge indicator as a "fuel" gauge. Seems it knows what I'm doing better than I do.

· CB (not verified) · 3 years ago

All I hear is you are learning how to guage an electric car range. The novelty is the only thing "wrong" here. The first week of my Leaf, I had a couple "panic" moments when I didn't realize what would drive my range down more than I expected. And I wasnt just relying on the "projected range" that I knew was only a current "estmate" subject to much change. You learn.
I also stopped for some "emergency juice" at a Nissan dealer, and got home with 3 miles showing for range. Phew.
But now I know that the SOC meter is the direct data on current charge. It can still discappear if I drive 75 instead of 60 pretty quickly. I know that now. If I am squeezing miles, I dont zoom in D, and get "shocked" by the projected miles disappearing. Now I am 100% OK with the data from the SOC. There may be better possible, but it is great now that I am not in "new user panic" mode.

· · 3 years ago

All bets are off when the last joules are in the battery, but in general can one not simply multiply bars remaining by 8% for a raw SOC meter ?

· · 3 years ago

Here is what some are saying on the MNL forum. These are conservative numbers.

6 miles / bar when driving @ 60 mph. (same as saying 72 miles range)
5/70 (60 miles range)
7/City (84 miles range)

Now, when you look at the dash and see 6 bars remaining - it could mean the 7th bar just disappeared. It could mean the 6th bar is about to disappear - so we are dealing with some 5 to 7 miles variation in the calculated range.

· Larry, Richmond VA (not verified) · 3 years ago

It seems the Leaf really has 2 deficiencies, one is a display deficiency, the other is that the software isn't fine-tuned just yet. While it's true that SOC calculation isn't trivial, Leaf has to be basing its mileage estimate on SOC anyway, so it certainly could and should share with us that SOC estimate. From this and other stories it's clear that the Leaf software puts far too much weight on the driving style for the last few minutes as opposed to your average driving style over the previous month or so. This weighting should be programmable by the user. And since the main variable is freeway vs surface roads, having a mileage estimate for each would be appropriate.

The more difficult issue is the SOC estimate itself. The problem here is that unlike lead-acid cells, lithium cells have an almost flat voltage curve until they are almost exhausted, so the pack voltage is not that useful in calculating SOC and in most cases it's more accurate to estimate remaining charge by starting from full and counting the electrons going out, then subtracting that from the pack capacity. But the capacity will vary a bit between individual packs and cells, and will decrease with age - and even the aging will depend on driving and charging style, and probably temperature. All of this can in theory be taken into account. The software could even use those rare occasions when the pack is depleted to the point that voltage really starts dropping, to estimate the pack's capacity and thus correct for pack aging. But I doubt that the software is anywhere near the point of doing all this accurately. So the bottom line is that to give the SOC and range estimates Leaf is presumably subtracting two numbers, both of which are subject to errors of, say, a few percent. A combined 6% error is a big deal when you're at 20% SOC.

But having a display of quantized bars, if that's what Leaf has, is just plain stupid. I had one of those in my lead-acid EV and I taped it over and finally removed it, it was so distracting. Just glancing at the digital voltmeter at stoplights gives a much better SOC estimate.

· · 3 years ago

Well, no one is to blame. Range anxiety is real. I've felt it in my ICE vehicle on more than one occasion, driving through the mountains of West Virginia in summer time, running the air-conditioning and not knowing when the next filling might come. And the gas gauge reads differently when going down hill then it does uphill, with the trip computer's estimate of miles until empty going up and down by 5 or 10 miles. The only cure will be greater range, more and faster recharging options and experience with the vehicle. But there is probably no on-board measurement that is going to set at ease the mind of a driver who is going to just barely make it home.

· · 3 years ago

@Larry, Richmond : "A combined 6% error is a big deal when you're at 20% SOC.

But having a display of quantized bars, if that's what Leaf has, is just plain stupid."

Those two statements are contradictory. If you can't estimate SOC accurately don't show a dummy SOC figure giving the impression of more accuracy than there really is. Instrumentation 101.

· · 3 years ago

I charged my LEAF to 80% last night. I awoke to the dispiriting estimated driving range of 51 miles. I presume because I drove 35 miles pretty quickly (hit 91MPH at one point) home from Palo Alto yesterday. The car now thinks I drive like a maniac and in its wisdom wants to protect me from running out of juice. But the car doesn't know me. It doesn't know what I will do today. Just tell me how much is in my battery pack.
For all Ford's good words, the picture in Brad's recent piece tells the story. No numeric SOC. Yet.

· · 3 years ago

@Marc -

A new advertising slogan for EVs: "We'll only tell you enough information to break your spirit!"

· · 3 years ago

I haven't seen an image of the SOC%, but Sherif said it will be there. I'll double-confirm that it will be there.

I think a lot of this comes down to designing systems that are dumbed-down for everyday drivers, but dumbing it too far down (and not allowing those who want the extra info to get access).

We'll keep fighting the good fight to make this crystal clear to OEMs.

· · 3 years ago

One more thought: The real problem happens when you're on the final bar in the LEAF. No way to know if it's 5% (which is fine for a quick errand a mile or two away) or dangerously low at 1%, which means no damn way should you go anywhere until some charging time.

· · 3 years ago

@Brad At this point the question isn't how dumb they think their "everyday drivers" are; it's how dumb are the carmakers. We're not asking for "extra info." We're asking for the most basic info - how full is the effin' tank? Percentages,btw, are generally learned in 7th grade math. Have we really got to the point where a scale of 1 to 100 is too complex?

· · 3 years ago

>> I think a lot of this comes down to designing systems that are dumbed-down for everyday drivers, but dumbing it too far down (and not allowing those who want the extra info to get access). <<

While I totally understand that nobody wants to scare off Joe Sixpack, this is NOT a case of either-or. I'm a user interface guy, and the EASY part is making available a simple and smart UI all in one. (the hard part is making those two UIs). It is easy to offer both because the car (or whatever device is in question) is initially set up for the idiot... er... I mean the average driver. And that average driver (the bulk of buyers) will never know anything else beyond the idiot lights and the "charge now" warning. Great. He's happy. The rest of us find on page 653 of the user manual a multi-key sequence that allows us to customize the dash display to our liking. All OBD2 info is available to choose from, and multiple screens can be set up to our liking. Now even the smart people are happy. Nobody loses in this scenario - so why can't anybody else incorporate this? I've been doing it for years for electronically controlled flashlights and bicycle headlights!

If you EV designer folks are out there listening, I am currently entertaining job offers. My public portfolio is pretty easy to find.

Darell, the EVnut.

· Chris T. (not verified) · 3 years ago

@darelldd: the problem with your solution is, it's far too simple! Nobody wants to do anything that simple! :-)

· · 3 years ago

@ Brad Berman · "The real problem happens when you're on the final bar in the LEAF.".

There is - drive around till you are familiar with the "bars" - like I did today. Got 18.4 miles after getting "low battery" warning / 0 bars.

· · 3 years ago

This whole problem would not exist if any of the following:
a) You're friend in Daly City had an EV charging station at his home or even let you use a 240 volt outlet in his home (of course the Leaf's paltry 3.3 kW - 15 Amp charging rate would not help as much as a more convenience charging suitable 30 amps)
b) Any of the places you stopped had a public convenience charger (again, the Leaf's paltry 3.3 kW isn't helping as much as it easily could)
c) There was a single DC fast charger anywhere between Daly City and Berkeley. (a $100,000 DC fast charge station split among 1000 SF, Oakland, Berkeley Leaf drivers is only $100 each - why is this so difficult?)
This isn't a user-interface problem. It's either a start-up problem (not enough infrastructure - yet) or an economical one (your friend hasn't made the grid accessible at his house)
With the Leaf, I basically assume about 5 miles per bar on the SOC meter and go with it. I live in mountainous areas so the guess-O-meter and power consumption measures are both pretty useless for me.

· Anonymous (not verified) · 3 years ago

good news

· Listen to christopher (not verified) · 3 years ago

I'm on the wait list for an August 2011 delivery in Central Cal. I have to say, the battery charge indicator issue is a waste of time. This is all about range, real range. As a pilot, if I fly a jet or a cessna, if I'm climbing, my plane's range is severely limited compared to being in cruise or descent. However, pilots, plan every leg of a long trip based on fuel and have a very good idea of fuel consumed. They must then have a 30 minute reserve at their destination for example under VFR conditions. Not running out of gas is pretty important in a plane!

Still, it happens, when people push the envelope. To me, it sounds like Christopher said it all: we are a bunch of early adopters and the problem here is the Leaf's range is not enough to replace your ICE car. Remember, the design philosophy of electric cars is that the "average" driver drives 40 miles a day. So Nissan has exceeded that by say, 25 miles. If a guarantee of 65 miles between charges in your daily "flight plan" isn't sufficient, then you simply should not have bought this car yet.

I know I don't drive that much in a day so the car is appropriate for me. However, if I get it and it does not cover that many miles per day, fully charged, then the car is a lemon and I will proceed accordingly.

As I fly in any plane, as I said above, the range can change hundreds of miles by going from cruise to climb power settings. The trick is to have enough "gas" in your Leaf and realistic expectations. You would be foolish to plan to drive 100mi in a day if that included anything other than a flat, 40mph drive in 70 degree weather.
If you live in a city like SFO, it's like going up and down in an airplane when you go up and down those big hills and your readings will be inaccurate. The only thing Nissan needs to "fix" is range!

· · 3 years ago

>> If you live in a city like SFO, it's like going up and down in an airplane when you go up and down those big hills <<

If you could create fuel in your plane as you descend, this analogy would work better. Certainly you don't get all of your energy back when you descend in an EV, but you get more of it back than you do in an airplane, in a gas car, even in a hybrid.

I am a bit confused as to why you say that the charge indicator issue is a waste of time... when you then go on to mention how important it is to know your available fuel on an airplane. Or is your point that you need to plan EVERY trip in advance and file the flight plan with your family? ;) While the plan analogy works on some levels, it is even more relevant to actually have EV-driving experience. And I speak from experience when I tell you that having an accurate SOC meter is one of the most important bits of information you can have available to you. The issue (not having a real SOC gauge) is not trivial.

· · 3 years ago

@darelldd, For an airplane, potential energy stored as altitude is the rough equivalent of recharging a battery in an EV. While you may be right that a Leaf can recover more energy than an airplane when descending, some aircraft, such as sailplanes can be pretty efficient. That efficiency is measured by the lift to drag ratio. A typical sailplane might in the 30:1 to 40:1 range for L/D and competition models can be considerably higher. A 40:1 L/D sailplane can can travel 40 miles forward for each mile of altitude lost in calm air. Such a clean aircraft would recover the vast majority of its potential energy (altitude) when diving and then climbing. Been there, done that (former sailplane and airplane pilot).

Many years ago I had a family friend who flew DC-9s on inter-island hops in Hawai'i. They never really get to cruising altitude, they just power up to an appropriate altitude, then power all the way back and glide to the next island (yes, really). As I recall, he said that the DC-9 had an L/D of 19:1 at 250 knots.

Yes, airplanes aren't particularly efficient in normal operation and they certainly don't "recharge" when going downhill, but you might be surprised at how little energy they use when gliding "downhill". I don't know what zero lift Cd a 40:1 sailplane has, but it must be very low by car standards, perhaps on the order of 0.01.

· · 3 years ago

@ dgp - well, potential energy is the same no matter what the craft! I think you got my point though.

Yes, running up and down hills will eat up more energy than the same speed on flat. But that hilly RT in a car that can recover lots of the potential energy does a LOT better than one that throws it all away. And in all instances planes, cars, etc... every one of them can use the potential energy to get further "down the road."

· · 3 years ago

@darelldd, Of course the real problem with an aircraft analogy is that when landing the airplane/sailplane throws away all its accumulated potential and kinetic energy via "dirty" flying (spoilers/flaps, flying at inefficient speeds, slipping) and braking (reverse thrust in the case of jetliners or turboprops). At least with EVs most of the energy of descent or slowing can be converted back to electricity and stored for use later.

· · 3 years ago

@Brad : "One more thought: The real problem happens when you're on the final bar in the LEAF. "

here is the Thumb Rule you were looking for. Something one could print and put it in the car for a spouse or someone not as geeky to use, for eg.

Not sure whether the following picture would showup ...

Anyway, here is the thread at MNL.

http://www.mynissanleaf.com/viewtopic.php?f=31&t=4295

· Leaf Owner (not verified) · 3 years ago

After reading all the comments I have to share how I deal with estimating range in a simple and straightforward manner. I reset one of the trip odo's when the battery is at full charge. Then I monitor the average miles per Kwh reading from the energy display. Knowing that Nissan allows the Leaf's battery to use up 95% of the battery's 24Kwh capacity yields a conservative usable Kwh of 22Kwh. I then multiply the average miles/Kwh readout times 22 to get the initial range. Then let's say I've averaged 4 mi/Kwh for 50 miles already. That would yield an energy used figure of about 13 Kwh. Then 22-13= 9 Kwh remaining. Now if I average only 3.7 mi/Kwh (say I'm on the highway now), my remaining range is 33 miles. Sure it takes a little mental math, but since I'm going slower and enjoying the experience anyway, it keeps things interesting!

· · 3 years ago

@Leaf Owner (not verified) · "yields a conservative usable Kwh of 22Kwh"

Yes - I'm suggesting 21 kwh instead of 22kwh. That seems to be close to emperical data.

http://www.mynissanleaf.com/viewtopic.php?f=31&t=4344

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