Remarkable shortfall against predicted range: yours?

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DeaneG

DeaneG

Well-known member
Joined
May 4, 2010
Messages
1,110
Location
Cupertino, CA
I've noticed some pretty hair-raising behavior of my range display lately, after getting the April software update and adding my carpool lane stickers (higher freeway speeds).

Here's the scenario:

1) Charge to 80% at home. Range indicator says "77 miles".
2) Freeway 12 miles slightly downhill to airport. Range indicator says "67 miles", pretty good, a 10 mile indicated decrease for a 12 mile trip.
3) Freeway 12 miles slightly uphill back home. Range indicator says "26 miles", an indicated decrease of 41 miles for a 12 mile trip.

I was driving 70-75 mph each way, not much wind.

Has anyone managed worse than this?

My hope is to collect some more worst case range data points on this thread rather than suggestions to slow down ;)
 
75mph is killer on the range...Try it for one day at 55 or 60mph and see what the difference is....

The 100 mile range that is talked about for the Leaf (using the LA4 cycle) is mostly city street-type driving with a pretty short burst for a few seconds to 55 mph.

Have you had the software upgrade done?
 
Your numbers seem inline with what I saw both before and after the update: I live at the top of a hill and saw similar numbers both before and after the update. That wild behavior is simply the result of it using the last 5 miles or so to compute your range remaining on the assumption that your driving habits will remain that way for the rest of the life of the vehicle (grin)! Thus, uphill numbers are very different that downhill numbers.


DeaneG said:
I've noticed some pretty hair-raising behavior of my range display lately, after getting the April software update and adding my carpool lane stickers (higher freeway speeds).
Click to expand...
 
DeaneG said:
My hope is to collect some more worst case range data points on this thread rather than suggestions to slow down ;)
Click to expand...

Your Range = 21 * Miles/Kwh (100% charge).

You should reset your m/kwh for the return trip if you want range you are getting for that segment.
 
DeaneG said:
2) Freeway 12 miles slightly downhill to airport. Range indicator says "67 miles", pretty good, a 10 mile indicated decrease for a 12 mile trip.
3) Freeway 12 miles slightly uphill back home. Range indicator says "26 miles", an indicated decrease of 41 miles for a 12 mile trip.
Click to expand...

I don't have my Leaf yet, but that doesn't sound completely unreasonable to me. It was basically saying that you could have gone 67 more miles of downhill at that speed, and 26 more miles at that speed going uphill. Based on your SOC readings and rate of change, would those predictions have turned out to be in the ballpark?

The range indicator can only be accurate if you are driving at a constant rate of speed on a flat (or constant grade) surface. Given that we rarely actually drive that way, it will be off. However, if you *have* been driving under fairly constant conditions for the last 5 miles (or whatever the moving average window is), it seems like it can be a useful predictor of the future assuming nothing changes.
 
Yeah, the range meter gets really scary at the end of an uphill drive. I took a 50 mile round trip with half going uphill when I only had just over 50 miles of range left. By the time I got to the top (25 miles) it said I only had 13 miles left. But, I wasn't worried. On the way down, I actually ended up with 15 miles left at the end of the trip. More than it said I had at the start of the downhill portion. Don't let hills spook you if you know it's round trip and you were good before you started up the hill. Now, if you're only going uphill and not coming back down before the halfway point, yes - you could get into trouble easily...
 
DeaneG said:
...
My hope is to collect some more worst case range data points on this thread rather than suggestions to slow down ;)
Click to expand...

I've seen some pretty amazing fluctuations, nothing too surprising since being reminded of the effects of elevation and exponential wind drag with added speed.

If you took an ICE vehicle and were given the miles per fluid ounce of a 3 gallon tank and concerned yourself with the fluctuations in consumption based on the shifting physics of elevation and speed, in 5-10 mile samplings, you'd probably be horrified by how much it changes, especially if you had to make it back to your garage to refuel. Expecting to be able to ignore drag with such a small margin of reserve simply reflects all the years we've been driving around vehicles with relatively large fuel tanks that have allowed us to ignore our waste.

These laws of physics are not unique to the Leaf, more that we have an opportunity to take a microscope to them and that we are early adapters, motivated to pay attention by a small fuel tank and sparse filling stations.

It would be helpful if the range estimate could consider cumulative changes in elevation, weather and so forth for a round trip, before even beginning the return leg of the trip and even be able to factor the results from the last time the trip was made... in time perhaps.

g
 
GaslessInSeattle said:
If you took an ICE vehicle and were given the miles per fluid ounce of a 3 gallon tank and concerned yourself with the fluctuations in consumption based on the shifting physics of elevation and speed, in 5-10 mile samplings, you'd probably be horrified by how much it changes, especially if you had to make it back to your garage to refuel.
Click to expand...
A very good point - with a battery large enough for say two roundtrip commutes, and a more-damped range estimate (to avoid predictions based on half a roundtrip), much of the issue would be moot.
 
The mileage estimator is a random number generator. You can't use it, and saying that you "have 26 miles remaining" is meaningless. The bars are more useful.

Your experience appears typical and expected. At 60-65 MPH the range is about 80 miles. You're only charging to 80%. The difference between going 60 MPH and 75 MPH could easily be 75 wh/mile, meaning you might only get 70% of the 65 miles you started with. Run the numbers and you get 80 miles X .8 charging penalty X .7 speeding penalty = 45 miles. 45 miles - 24 miles = 21 miles.
 
My first drive in the NYC Hertz LEAF was uphill to one of the highest spots in the immediate area, the New Jersey pallisades. The trip out was 21 miles, range indication went from 96 to 50. The downhill return trip was 26 miles, range went from 50 to 47 miles. So I drove a total of 47 miles according to the odometer, while the range indicator dropped 49 miles.

If I can end up renting the Hertz LEAF for a couple days to bring it to my home north of Philadelphia, I will go 77 miles each way, with about a 300 foot climb on the way home. I think the major changes in elevation along the route are the Holland Tunnel betweem NYC and NJ and hills on either side of the Scudder Falls bridge across the Deleware River from NY to PA. I'm thinking that if I drive US 1 and keep it in ECO at 55 mph, this trip should work OK. Not too many charging opportunities along the route, but there is an L1 on the Chargepoint network at the Ewing Element hotel about 19 miles from my house. I would think that I would probably be wise to pull in and pick up a few miles if I have less than 25 miles indicated range at that point. If I've got 30 or more, I would think the last 19 would be no problem...
 
I want the capability to blank out the erratic mileage display (or at least replace the mileage estimate with a 'percentage' of charge remaining). Otherwise, the number of bars seems to be a reliable and consistent metric.

On my 'old-fashioned' combustible engine vehicles, there is no mileage indicator on my fuel gauge, and those gauges have served me well for many years.
 
SanDust said:
The mileage estimator is a random number generator.
Click to expand...
Well, it predicts depending on how you have been driving. If you change the way you have been driving (like going from 30 mph city roads to 70 mph highway) obviously the est range won't be correct.

This is what I wrote in another forum ...

All auto makers have a simulation software that can tell you the watts/mile - given the speed. All that the software needs to figure out is the speed and likely speed variations. Then take elevation changes into account. The speed can be guessed using past history, speed limits and the traffic conditions. Given a destination, the software can figure out all this.

BTW, one of the things people crib about Leaf is this. It shows, let us say, 70 miles of range. Then, the person drives for 20 miles and now it shows 40 miles of range. The person somehow feels "cheated" !

One option would be to show the expected range - along with the speed used to calculate that range. If the driver drives faster, he should expect lower range.
Click to expand...
 
mbutter said:
I want the capability to blank out the erratic mileage display (or at least replace the mileage estimate with a 'percentage' of charge remaining). Otherwise, the number of bars seems to be a reliable and consistent metric.

On my 'old-fashioned' combustible engine vehicles, there is no mileage indicator on my fuel gauge, and those gauges have served me well for many years.
Click to expand...

+10000

It's nice to know the range when you want it. But it really freaks you out at first going uphill. :)
 
mbutter said:
On my 'old-fashioned' combustible engine vehicles, there is no mileage indicator on my fuel gauge, and those gauges have served me well for many years.
Click to expand...
My Chevy Malibu has a "fuel range" indicator, and it doesn't seem to be any more accurate that the LEAF's estimated range indicator. The main difference is that the Malibu has about 300 miles range per tank given my normal route and style, the LEAF will have substantially less.
 
evnow said:
Well, it predicts depending on how you have been driving. If you change the way you have been driving (like going from 30 mph city roads to 70 mph highway) obviously the est range won't be correct.
Click to expand...
I'm not finding it to be even close in that regard.

For example, for three days I did mostly freeway driving, at ~70mph. My range was around 65miles, as expected.

On the fourth day, after a full charge, I can STILL get into the car and see a predicted range of 80 to 90 miles. This is totally bogus. It does not reflect the way I've been driving. I would expect it to predict 65 miles of range, or stick to some reference point that is consistently off. Instead, it seems to have some kind of built-in "optimism" about me changing my driving habits.
 
GroundLoop said:
I'm not finding it to be even close in that regard.

For example, for three days I did mostly freeway driving, at ~70mph. My range was around 65miles, as expected.

On the fourth day, after a full charge, I can STILL get into the car and see a predicted range of 80 to 90 miles. This is totally bogus. It does not reflect the way I've been driving. I would expect it to predict 65 miles of range, or stick to some reference point that is consistently off. Instead, it seems to have some kind of built-in "optimism" about me changing my driving habits.
Click to expand...
It's memory isn't that long. If you spent the last couple of miles before getting home driving city streets, that's what it will remember.
 

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