madbrain said:
TonyWilliams said:
If you started and ended at about the same SF Bay Area elevation and drove 50mph with the heater off, you would have gotten an economy of about 4.8 without the heater.
That is simply not true - starting and ending at the same elevation really doesn't predict much. The extra amount of energy used to go uphill is much more than what's comparatively saved or regenerated when going downhill.
I'm not comparing a drive to Lake Tahoe elevations after cresting a 12,000 feet Colorado summit. I'm making a comparison to an elevation change between Livermore and San Jose (as a typical Bay Area drive that YOU might make in your LEAF). Livermore airport is 400 feet elevation, San Jose airport is near sea level. That drive, round trip in EITHER direction won't appreciably change the economy compared to what a heater can do.
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You are correct in your assertion; more power is used going up hill than gained going down hill (which is also in the range chart). But, your application is skewed. The difference in economy of driving 50mph on a perfectly level road and the same road trip distance at 50 mph from San Jose to Livermore is negligible compared to what the heater can do. (clearly you dispute that). There just aren't any high elevation mountain passes to get to Livermore, and not enough elevation changes for big impacts.
Yes, if you started from San Jose with a reset economy dash gauge, you might get 4.4miles/kWh at 50mph with the heater off. Then, on the return, once again resetting the economy meter, you might get 5.0 miles/kWh. On level ground at 50mph it would have been 4.8 miles/kWh, while the equidistant average of your SJC-LVK jaunt is 4.6 miles/kWh. The difference in economy between the two is about 4% (between a level road at 50mph with no heater compared to the same parameters on a round trip of SJC-LVK-SJC). Hopefully, this makes sense.
The difference in economy using the heater, however, is potentially HUGE in comparison. Since I don't know how many kWh your burned heating the cabin, it's not unusual for a 30% loss of economy. The loss of economy going to LVK is tiny in comparison to a level road.
It's the amount of uphill that matters.
Hence my example to Livermore. Given your examples with exceptional short (half mile) tests would be difficult. I don't drive in half mile spurts, or plan that way. That data would have no meaningful use to me, or the average driver.
For instance, going up to Livermore and back won't kill the economy like the heater will.
I don't think I would dare going there in my Leaf. Depending on the route it could be an 80 mile roundtrip from my place to the city center. Forget hills and heat, this is just beyond the Leaf's range.
Well, again, you may dispute this, but having done many trips in a LEAF well over 80 miles, yes, the LEAF physically can do it. Thats in the range chart, too. If its not comfortable for you, obviously don't do it. You would have to be able to accurately calculate the energy in the battery, and forecast the consumption. The tools are out there for you to do this.
The available energy is most easily calculated with a Gidmeter. You may not have that, but there are other ways. Predominately, the amount of charge (by counting the crude delineation 12 fuel bars or referencing the Low Battery or Very Low Battery warnings), the amount of degradation, and the losses from cold temperatures on the battery will determine your available kWh's. All this assumes an otherwise proper working battery.
Economy is nothing more than the reading from the dash since its last reset. If you want accurate information for a particular trip, you need to reset the economy gauge first. The economy data will reflect the heater use, also.
Then, total range is nothing more than:
Available kWh * Economy Miles/kWh = Range in miles
The Range Chart has all the fundamental data that will affect range in a LEAF.
No, it simply does not. Speed and initial state of battery are the only factors considered in that chart.
I don't think you are actually looking at the same chart that I'm referring to. If you only looked at speed and full bars as the whole chart, yes, you would have difficulty with accurate predictions. There are Apple and Android apps that use the range chart for their base data that may be easier for you to understand all the parameters. They can import routes, elevations and mileage from Google, as well as ambient temperatures.
Just one example - that one 4.1 miles roundtrip from home to the grocery and back at a peak speed of 35 mph had a 2.3 miles/kWh average on carwings. Starting and ending elevation was exactly the same.
Problem number one. The base chart data is not "peak" speed. It is
steady speed (XX mph
EXACTLY -or- X.X miles/kWh) at defined parameters. If you are not at that speed in those parameters, then you must use the economy * available kWh to determine range. It's really not that hard. The speed will only match the economy in the prescribed parameters (level, dry, heater off, no wind, windows up, etc).
Again, the chart is SPECIFICALLY notated that it does NOT use CarWings or GOM data. Certainly, you're welcome to use any data you want, but I guarantee that there won't be accurate information when you are doing exactly what is stated not to do.
According to your chart, with a speed of 35 mph, I should have gotten 6.3 miles/kWh. Carwings may not have 100% accuracy, but it's definitely not off by a factor of 3
Hopefully, the above clears this up.
For most of that roundtrip, the speed was actually well below 35mph. Your chart doesn't even go below 35mph. But if it did, it would predict even higher miles/kWh than 6.3 .
If you looked at the chart, you would see that it economy increases all the way to about 12mph. Nobody is driving the car with economy above 6, so making the chart speeds lower would be foolish.
The difference between 2.3 and 6.3 miles/kWh is huge. I believe this difference is explained by the combination of hills and heat.
I hope I'm helping you understand why, but I sense you are just finding reasons why the range chart is wrong.
Unfortunately, your chart also does not account for the heater and defogger being on. And other factors like acceleration also play a factor. In residential areas the number of stop/red lights will play a factor too.
Yes, heater is the NUMBER TWO killer of range, right behind speed. I cannot accurately determine how many kWh's that you might use. Only you can. There is a note to help you determine that (in the range chart).
It would take a more complex algorithm than a 2D table to get a more accurate estimate of the energy usage based on all these other factors.
Every major factor to range of the LEAF is represented on the chart. That includes elevation, ambient heat, elevation (to consider density altitude), heater power consumption, wind, uphill / downhill, etc. Things that are impossible to define with an absolute like snow, rain, etc are mentioned, but not defined. Those last issues can also have gigantic impacts on range, but again, impossible to absolutely define.