miles to go estimate pretty inaccurate

[RustyShackleford]

Kind of a basic question from a new owner (2018 SV model): Yesterday I left home with the dashboard showing that I had 137 miles of range; when I got home it showed 50 miles, for a reduction of 87 miles. I google-mapped my wanderings, and it came to a total of 65 miles; that's a pretty big discrepancy.

I'm not real clear on how the car comes up with the remaining-range estimate. I thought I'd heard it's somewhat adaptive to how you've been driving. Most of our driving has been fairly short range, 5 miles into town from semi-rural home, then a lot of stop&go in town. But yesterday, most of the driving was on the freeway at 75 mph or so. I'm thinking that unlike an ICE vehicle, the EV is more efficient in stop&go because of regenerative braking. So the car was estimating that 137 miles based on all that previous short-range driving, and then yesterday I zoomed down the freeway with no regen. Make sense ?

What's a good way to know the true range better ? I've got LeafSpy Pro, and understand it gives a more accurate picture of how much juice is in the battery. But I'm a bit unclear on how you give it accurate estimates of your expected miles per kwh.

 

[DougWantsALeaf]

If not using Leaf Spy, just use your % remaining as miles remaining, knowing you are being hyper conservative for all but the coldest weather or x by 1.3-1.5 in 60-80 degree weather and not doing 70+ on the highway. 40kW version. For the 62, it’s 2 miles per % relatively conservative (in summer if driving very conservative, you can do 3 miles per %)though I find the GOM to be pretty stable above 80% and below 50%. In between it hides range, so your range drops a bit faster then the miles used.

 

[alozzy]

Mileage is going to suck with an ICE at 75 mph too. Your LEAF is likely more aerodynamic than your past ICE cars, so it's not that the LEAF is uniquely "inefficient" at highway speeds. If you really need to eek out extra range, try driving at 65mph instead, you'll notice a huge difference.

The GOM (guess-o-meter) is called that for good reason, although I figured it would be better in a newer LEAF - guess not...

The good news is that, after a few months of driving an EV, you develop a gut instinct for remaining range that's more accurate than the GOM.

 

[LeftieBiker]

The range estimator uses the last few minutes of driving efficiency, plus the remaining state of charge, to estimate range. The 2018+ uses additional information (not sure what) because it is actually more accurate than the previous Leafs. I suspect that your trip had either a fairly large elevation change, or some spirited driving (or high freeway speeds) involved...?

 

[RustyShackleford]

The range estimator uses the last few minutes of driving efficiency, plus the remaining state of charge, to estimate range.

So it wasn't very accurate at the beginning of yesterday's freeway drive (137 miles) but became more accurate when I started zipping down the freeway at 75mph, hence the GOM dropped 87 miles while I drove 65 miles. Make sense. Just gotta be aware. But dang, the car sure makes it easy to go too fast !

 

[WetEV]

But dang, the car sure makes it easy to go too fast !

That was the first thing I noticed the first time I got to drive an EV. A few quiet streets, then onto a freeway.
Glanced down at the speedo, and was doing 80+ MPH in a 55.
Lucky for me, nobody around me...

 

[LeftieBiker]

Yup. The GOM tends to get more and more accurate as you drive, until it finally gets the estimate right - as you arrive at your destination. With older Leafs I suggest using the more accurate (pessimistic) range estimator in the Nav system, but I haven't needed it in my 2018. But then I rarely drive 75...


WetEV slipped in ahead of me.

 

[DougWantsALeaf]

Agreed, if you can keep it under 70, range will generally meet or exceed expectations. If you can tolerate driving at a constant power outage vs. speed, the car does much better than estimates. (Requires some patience and practice though)

 

[webeleafowners]

Agreed, if you can keep it under 70, range will generally meet or exceed expectations. If you can tolerate driving at a constant power outage vs. speed, the car does much better than estimates. (Requires some patience and practice though)

This. We find the GOM to be very accurate. But speed limits are lower here and speed kills range. It essentially comes down to how fast you go.

 

[Nubo]

GOM is for entertaining (and sometimes alarming) your passengers. It can serve *some* purpose as a second-order check on a long trip to see whether or not the ratio between the GOM and distance to destination is changing positively, negatively, or staying the same. This can give you early warning that you need to drive more economically or that you have sufficient cushion.

 

[LeftieBiker]

GOM is for entertaining (and sometimes alarming) your passengers. It can serve *some* purpose as a second-order check on a long trip to see whether or not the ratio between the GOM and distance to destination is changing positively, negatively, or staying the same. This can give you early warning that you need to drive more economically or that you have sufficient cushion.

Again, if you have a Leaf with Nav, then use the blue (?) energy button on the steering wheel to bring up the nav map with two range estimates as concentric circles overlaid. The inner circle is pretty accurate if there are no large changes in elevation. The outer circle/estimate corresponds with the GOM.

 

[RustyShackleford]

GOM is for entertaining (and sometimes alarming) your passengers. It can serve *some* purpose as a second-order check on a long trip to see whether or not the ratio between the GOM and distance to destination is changing positively, negatively, or staying the same.

So what do you do ? If LeafSpy Pro, how do you get the miles/kwh (or is it gids/mile) number you input into the app ? Because your estimate is only as good as that. I guess ideally one could have a number of figures, and select the right one according to what kind of trip they are undertaking or planning to undertake.

 

[LeftieBiker]

GOM is for entertaining (and sometimes alarming) your passengers. It can serve *some* purpose as a second-order check on a long trip to see whether or not the ratio between the GOM and distance to destination is changing positively, negatively, or staying the same.

So what do you do ? If LeafSpy Pro, how do you get the miles/kwh (or is it gids/mile) number you input into the app ? Because your estimate is only as good as that. I guess ideally one could have a number of figures, and select the right one according to what kind of trip they are undertaking or planning to undertake.

There could be a range of assumptions, from "Little Old Lady" to "Little Old Lady From Pasadena."

 

[RustyShackleford]

GOM is for entertaining (and sometimes alarming) your passengers. It can serve *some* purpose as a second-order check on a long trip to see whether or not the ratio between the GOM and distance to destination is changing positively, negatively, or staying the same.

So what do you do ? If LeafSpy Pro, how do you get the miles/kwh (or is it gids/mile) number you input into the app ? Because your estimate is only as good as that. I guess ideally one could have a number of figures, and select the right one according to what kind of trip they are undertaking or planning to undertake.

There could be a range of assumptions, from "Little Old Lady" to "Little Old Lady From Pasadena."

Haha, yeah. But I mean, each driver learns what his/her own numbers are, and I think (from my little time messing with it) that LSP makes that pretty easy.

 

[DougWantsALeaf]

LeafSpy shows you the miles remaining based on the efficiency you pick. I generally set the buffer to 3% (about 2 kWh) and put the efficiency a couple tenths below what I am averaging to be safe.

 

[BillHolz]

But dang, the car sure makes it easy to go too fast !

That was the first thing I noticed the first time I got to drive an EV. A few quiet streets, then onto a freeway.
Glanced down at the speedo, and was doing 80+ MPH in a 55.
Lucky for me, nobody around me...

I concur about being too easy to go too fast. In 2016 I took a 2013 S model on an extended test drive to see if a Leaf would be suitable for my then 54 mile round trip commute. I was speeding any time I was not watching it which made not having cruise control a deal breaker on that S model.

 

[Titanium48]

... I'm thinking that unlike an ICE vehicle, the EV is more efficient in stop&go because of regenerative braking. So the car was estimating that 137 miles based on all that previous short-range driving, and then yesterday I zoomed down the freeway with no regen. Make sense ?

It's not just regenerative braking. An idling ICE is still using fuel while you are stopped at a light, and ICEs are very inefficient at low power outputs. Electric motors use nothing at rest and efficiency is high at low and medium power outputs, but drops a bit at high power due to increasing resistive losses. The result is that the increasing ICE efficiency as speed and power demand rises masks the effect of the dramatic increase in aerodynamic resistance (proportional to speed squared) and fuel economy doesn't drop much until you are going really fast and the ICE efficiency starts to plateau. An EV benefits greatly from speed reduction because drag drops but efficiency doesn't.