Full charge mileage displayed isn't 238

Airbesar · Jan 16, 2017

I probably didn't read the right stuff in the manual, but I was a little surprised this morning to find the car display saying that the charging was completed but only 189 miles were available. The explanation I got from the dealer is that the car considers my driving habits and things like the temperature to develop a mileage estimate. I'm OK with things working this way but I thought I'd post in case others become similarly surprised.

As the outside temp warmed up, with the charger disconnected, the available mileage moved up to 192. The temp here in Sacramento this morning was about 35, and 50 this afternoon.

WetEV · Jan 16, 2017

Airbesar said:
I was a little surprised this morning to find the car display saying that the charging was completed but only 189 miles were available. The explanation I got from the dealer is that the car considers my driving habits and things like the temperature to develop a mileage estimate. I'm OK with things working this way but I thought I'd post in case others become similarly surprised.

I guess I'd be far more surprised if the car when fully charged always displayed 238 miles on the "GOM" or "Guess-O-Meter", which is what the range estimate the car presents is often called. I'm glad to hear that it doesn't.

Don't pay too much attention to the GOM. Remember that it is just a guess based on less information than you have. At the top of a climb, will be too pessimistic. Before a climb, or after a decent, will be too optimistic. And so on.

The car can take past driving habits into account. You can take what your plans are into account. My driving ranges from city to mountains, busy freeways to quiet backroads. Sometimes I hypermile, sometimes I don't. I've driven the Leaf enough to know about what to expect on different roads and different driving styles.

The car can take the current temperature into account. I can look at the weather forecast where I'm driving to, and modify the range based on that.

I can look at maps and fancier tools to see the altitude gains and losses. The car can't. Once at the top of a mountain pass, the Leaf's GOM estimate was 6 miles: and I had over 40 miles to drive. I knew it was no worries, as the car was guessing based on climbing up a steep hill, and that wasn't what was going to happen next. Could have coasted to the destination, almost.

CGameProgrammer · Jan 16, 2017

It would be extremely odd if the calculated range was exactly 238 because that is only the combined average of the EPA's particularly city and highway testing cycles. The highway range was something like 220 and the city range was something like 250, but again that's only on the particular exact testing cycle the EPA uses. Obviously your mileage will vary. Drive 50 mph everywhere without stopping and your range will be huge. Drive 90 mph while constantly accelerating and decelerating and your range will be short.

Obviously.

dandrewk · Jan 17, 2017

Was that range the average mileage left? The 238 mile range (or whatever the max) should be close to the top number in the GOM range.

Zoomit · Jan 17, 2017

CGameProgrammer said:
It would be extremely odd if the calculated range was exactly 238 because that is only the combined average of the EPA's particularly city and highway testing cycles. The highway range was something like 220 and the city range was something like 250, but again that's only on the particular exact testing cycle the EPA uses. Obviously your mileage will vary.

This ^

The Guess-o-Meter term comes from LEAF owners and while it may be fitting for their estimates, it's derogatory and it isn't fair to project that to the Bolt EV estimates. The predictions I get from my Spark EV are much more reasonable than what I've read about the LEAF estimates. While there's definitely still some interpretation involved (at the top or bottom of a hill, when transitioning from city to highway driving), it's relatively close. I'd expect the Bolt EV to be similar or better.

Airbesar · Jan 17, 2017

GOM - I love it. The 189 was the figure in the middle of that. the top of the range was 222. I think the bottom was about 154.

As other people point out, those numbers move around while you're driving. I was in the car for about 5 hours today. Stuck in traffic at a slow but steady pace, the numbers started moving up. The hills definitely drove the numbers down. There was one point when I got back in the car after being away for half an hour, and the middle GOM number was then 10 miles higher than when I left the car. Temps had gone up. As is said, it's just a rough estimate.

dandrewk · Jan 18, 2017

Zoomit said:
CGameProgrammer said:

It would be extremely odd if the calculated range was exactly 238 because that is only the combined average of the EPA's particularly city and highway testing cycles. The highway range was something like 220 and the city range was something like 250, but again that's only on the particular exact testing cycle the EPA uses. Obviously your mileage will vary.

Click to expand...

This ^

The Guess-o-Meter term comes from LEAF owners and while it may be fitting for their estimates, it's derogatory and it isn't fair to project that to the Bolt EV estimates. The predictions I get from my Spark EV are much more reasonable than what I've read about the LEAF estimates. While there's definitely still some interpretation involved (at the top or bottom of a hill, when transitioning from city to highway driving), it's relatively close. I'd expect the Bolt EV to be similar or better.

The Guess-o-Meter term does come from Leaf owners. It is meant to be derogatory. And it is NOT a "guess"-o-meter.

The Leaf's battery range estimator is not linear. It was programmed to be optimistic when the battery was full or near full and to be pessimistic when the battery about 25% juice left. In between, the estimate was accurate. It is completely repeatable, and like other range estimators takes into consideration climate control usage, drive mode, conditions etc.

As to why Nissan programmed it that way, it's anyone's guess. I assume the purpose of under-reporting range when the battery is low was to help prevent running out of juice. Personally, I think it's much better to keep that gauge linear.

BTW, every ICE car I've owned also had a fuel gauge that was a GOM. I'm sure we've been there - get a full tank, drive 100 miles and the needled barely moves from "F". Drive another 75 miles and it's half full. Then watch that needle take an accelerated dive towards "0".

WetEV · Jan 18, 2017

dandrewk said:
The Guess-o-Meter term does come from Leaf owners. It is meant to be derogatory.

I think of it as cautionary, and predates the Leaf. Any range estimator is a GOM.

A quick web search finds this:

http://www.renepotvin.com/cal.htm

An almost 20 year old fish story.

The GOM can't use any information that the car doesn't have. The GOM doesn't know if I'm going to run only the fan, just a bit of heat to clear the window, or really crank up the heat. It doesn't usually know where I'm going, although it could guess, and 4 to 5 days a week it could be very accurate. It doesn't know how I'll drive. The list of things it doesn't and can't know is long.

You need to remember the GOM is just a guess, not an accurate answer to how far the car can drive. As long as you remember that it is just a guess, and don't count on driving that exact distance before empty, you will do fine.

dandrewk · Jan 18, 2017

I totally agree. It does get more accurate and precise as the mileage gets very low. Even then, you have to take into account terrain. A GOM showing 8 miles left when you are 5 miles away means you should be safe... unless it's 5 miles uphill.

NeilBlanchard · Jan 18, 2017

Airbesar said:
I probably didn't read the right stuff in the manual, but I was a little surprised this morning to find the car display saying that the charging was completed but only 189 miles were available. The explanation I got from the dealer is that the car considers my driving habits and things like the temperature to develop a mileage estimate. I'm OK with things working this way but I thought I'd post in case others become similarly surprised.

As the outside temp warmed up, with the charger disconnected, the available mileage moved up to 192. The temp here in Sacramento this morning was about 35, and 50 this afternoon.

A LOT of things affect the range:

Your driving - your average speed and acceleration rate.
Air temperature affects the aero drag, and how much HVAC you use.
Elevation changes.
Road conditions.
How many people or how much stuff you have in the car.

Also, check you tire pressure, and pump it up to at least recommended, or to 40-44PSI.

Zoomit · Jan 18, 2017

Range at 35F might only be 75% of the range at 75F, even if no HVAC is used. The largest contributor to that loss is due to the "inherent slowing of the battery’s electrochemical reaction, which reduces the capacity while cold."
http://batteryuniversity.com/learn/article/discharging_at_high_and_low_temperatures

The increase in density at lower temperature, that leads to higher aero drag, only accounts for a small fraction of the ~25% loss due to temperature.

NeilBlanchard · Jan 19, 2017

I have been driving both a Leaf and an e-Golf for about 2 years, here in Massachusetts. The range loss at 35F vs 75F is only about 10%. You have to have temperatures below 20F to get anywhere near 25% loss; when you don't need to use the air heater. In fact, I think you need to go down to 10F to see that much loss, just for the battery heating.

Aerodynamic drag is much more significant than you think - at 30F air is ~6% more dense than at 60F (if my memory serves). A typical car, with a frontal area of about 24-25 sq ft - shifts about 4.5 TONS of air around it PER MILE.

Let that sink in.

Zoomit · Jan 19, 2017

When looking at temperature drops from 75F (24C) to 35F (2C):

Fleetcarma data shows that the LEAF loses about 13% range [1-66/76].
Fleetcarma data shows that the Volt loses about 36% range [1-27/42].
http://www.fleetcarma.com/nissan-leaf-chevrolet-volt-cold-weather-range-loss-electric-vehicle/

This thread shows the IONIQ Electric loses about 35% range [1-130/200].
http://www.ioniqforum.com/forum/234-hyundai-ioniq-electric-ev/1746-electric-range-7.html
http://www.ioniqforum.com/forum/attachment.php?attachmentid=505&d=1482987015

My experience in my Spark EV is that range drops around 20-25% between summer mornings and my mild winter mornings.

In this video, the Bolt EV loses about 14% range [1-(1152/338)/(238/60)] in slightly warmer "35-45F" temperatures.
https://youtu.be/uMgZT2WBXQo?t=6m6s

As a generalization, 25% is a reasonable assumption until more data is available; it could be better, it might be worse. But the point was that aero drag is only a minor portion of that effect.

The increase in air density when the temperature drops from 35F to 75F is 8% [0.0795/0.0735-1] and at 70mph overcoming air drag accounts for about 75% [225/300] of the energy used (per unit distance) to move a Bolt EV. So the increase in aero drag decreases range 6% [0.75*0.08].

The rest of the losses are primarily due to the battery reaction slowing down. For a LEAF the aero drag could account for 1/2 the total losses. For the Volt and IONIQ, it could be as low as 1/6th the total losses. For a Bolt EV, the increase in aero drag appears to be responsible for only 1/3rd to 1/4th of the range loss when temperatures drop from 75F to 35F.

like2bike · Jan 19, 2017

When I first got my LEAF I used the GOM and didn't even know I could display percent state-of-charge. By the time I found the % display I had realized how bad the GOM was and went by most the % display from then on. I glad to hear the Bolt may have a better GOM. I think the idea of have min/max/likely ranges is great. I hope someone figures out or learns what the algorithm for these three numbers is. It bugged me that I didn't know it for the LEAF and had to guess what the GOM was up to. No % display on the Bolt, so we need to use the GOM. There is a % display on the app, I've heard.

With my LEAF battery getting a little long-in-the-tooth, I think the GOM is probably worse than ever. Other LEAF owners and I have noticed that the % display becomes less linear with age. At 80% it's dropping fast and at 40% it is dropping not much faster than a new battery. I think this effect must be effecting the GOM accuracy too. I wonder if the Bolt will compensate for an effect like that. Come on EV engineers, it's not rocket science.

Nagorak · Jan 19, 2017

Zoomit said:
CGameProgrammer said:

It would be extremely odd if the calculated range was exactly 238 because that is only the combined average of the EPA's particularly city and highway testing cycles. The highway range was something like 220 and the city range was something like 250, but again that's only on the particular exact testing cycle the EPA uses. Obviously your mileage will vary.

Click to expand...

This ^

The Guess-o-Meter term comes from LEAF owners and while it may be fitting for their estimates, it's derogatory and it isn't fair to project that to the Bolt EV estimates. The predictions I get from my Spark EV are much more reasonable than what I've read about the LEAF estimates. While there's definitely still some interpretation involved (at the top or bottom of a hill, when transitioning from city to highway driving), it's relatively close. I'd expect the Bolt EV to be similar or better.

I just want to second this statement.

The range predictor in the Volt also seems very accurate. It seems like the car tracks your driving style and uses that to help project the range. If anything the prediction in the Volt is often too conservative. I'm assuming this holds for the Bolt as well.

That's totally different from the GoM in the Leaf which seems totally inaccurate. It's always wildly optimistic at the start. I think Nissan was trying to exaggerate the Leaf's range a bit, to be honest. I like the Leaf for what it is, but it is not without its shortcomings.

LeftieBiker · Jan 20, 2017

Actually, the 2013+ Leaf comes with an accurate range estimator as well. Nissan just, for some reason, decided to bury it in the Nav system and leave the GOM on the dashboard, gibbering away with wildly changing estimates. You can, however, press the Blue "E" button on the steering wheel, and a map comes up on the Nav screen with two concentric white circles, and two estimates of range. One is the GOM, but the other one (the "Probably Correct O Meter"?) is very good.

Nagorak · Jan 20, 2017

Unfortunately, I only have an S, so no NAV. Maybe I should have paid more for an accurate meter. :lol:

Actually, I wonder if the problem is the GoM is based on some really simple software. Maybe it requires more processing power to track the necessary parameters to get an accurate range? As far as I know the Volt and Bolt don't come without a NAV unit, so they would have that all by default.

LeftieBiker · Jan 21, 2017

The GOM is so terrible because it only uses a brief (maybe 5 minute) snapshot of the last bit of driving. Since that usually consists of slowing and then parking the car, it tends to read way too high at startup. It will slowly converge with real world range, so that right before you run out of charge, you finally have an accurate estimate of how much is left. ;-)

No SOC % on the Bolt?? Geez, what does it have? Charge bars? ;-(

SeanNelson · Jan 21, 2017

LeftieBiker said:
No SOC % on the Bolt?? Geez, what does it have? Charge bars? ;-(

It has estimated range, which is probably more useful to most people than a percentage of battery capacity.

roundpeg · Jan 21, 2017

I've been seeing guesstimated ranges of around 200-210 on a full charge in the mostly cold and wet weather we've been having. When it was warmer and drier for a few days and I could drive with the climate control off, I saw considerably more, closer to 220-230. Seat of the pants, I'd estimate that the heater saps about ten percent of the battery power. Of course it also loves local driving. Do a lot of that and the range predictions will increase.

Full charge mileage displayed isn't 238

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