How much farther could I have gone?

[NYLEAF]

A few days ago, I did my longest trip in the Leaf (without stopping to charge). I drove 68.2 miles from 100% to LBW. Before departing, I reset the Energy Economy screen (on the dash, not the touch screen), as well as the trip meter, and I averaged 4.2 mi/kwh for the trip. The outside temperature was about 45 degrees F, and my battery temperature bars raised from 4 to 5 during the trip. This was my route: http://goo.gl/maps/jBAVm

How much farther could I have gone? Any way to tell how much my battery has degraded, or how much energy I did not have available due to the cold temp? FWIW, I have had my Leaf for 11 months and at the time of this trip I had about 10,700 miles on the car.


Thanks!

 

[surfingslovak]

With these numbers, the range table predicts 81 miles of total range, and a usable battery capacity of about 19.2 kWh. How cold was the pack in your estimation. Did it cool down significantly or was it still close to room temperature?

Click to open

 

[NYLEAF]

I park outside (house was built in 1901, so no garage), so I have to assume the pack was at 45 degrees, since that's what it was pretty much all day that day.

 

[surfingslovak]

I park outside (house was built in 1901, so no garage), so I have to assume the pack was at 45 degrees, since that's what it was pretty much all day that day.

Right, at that temperature, we can expect about 6% less usable battery capacity per Tony's chart (1% for each 4 degrees below 70 F). You can likely chalk up the difference to battery degradation, which seems to be minimal in your case. That said, please take these numbers with a grain of salt. We know now that the instrumentation in the Leaf cannot be trusted 100%, and some of the sensors appear to be temperature-sensitive.

 

[DaveEV]

With these numbers, the range table predicts 81 miles of total range, and a usable battery capacity of about 19.2 kWh.

Isn't he better than that since LBW always comes on at 49 GIDs?

68.2 mi / 4.2 mi/kWh = 16.24 kWh + (49 GID - 7 GID (LBW - Turtle), 3.36 kWh) = 19.6 kWh

Given the cold temps I'd say his battery is nearly as good as new and had another 12+ miles range left.

Compared to my trip last weekend of almost 100% (car didn't stop charging, but had only 1 bubble regen which went away on a slight downhill run to the freeway) down to almost LBW (GOM=8 mi) driving 62 miles at 4.2 mi/kWh in 60F weather, I'd say his battery is definitely doing better than mine.

 

[RegGuheert]

Right, at that temperature, we can expect about 6% less usable battery capacity per Tony's chart (1% for each 4 degrees below 70 F).

Actually, Tony's chart does not tell you how much battery capacity you lose with temperature. Rather, it tells you how much range you use with temperature. While battery capacity does drop with lower temperatures, other factors also reduce range when the temperature drops and we do not have an accurate means to distinguish between these different effects.

 

[Caracalover]

Your trip looks like you went upstream the entire way, ending with an elevation gain. I didn't look to see how much, but it is pretty safe to assume you didn't really gain a lot of energy on the route you took. Doing the trip in reverse will likely use far less energy.

The beauty of this vehicle is it is also a power plant, so if you slow down and coast often, you can extend your range to almost double. This would require a route that you could utilize and drive 35 mph without stopping (Dreaming I know), but it is something to keep in mind as the battery ages.

So to answer your question, going further upstream you would be able to go another 10% or about 7 miles before I would be uncomfortable (I don't like to see turtle, and have only gotten there once). Reversing your elevation would allow you to gain energy in some areas, so you might be able to get another 20% or so if you drove carefully.

As for your battery, no worries. I lost a capacity bar and still make a 65 mile trip over a real mountain (East coast has hills) and plan to arrive at LBW. It seems easier to do now that I lost the bar (Compared to just before I lost the bar, which was close to your mileage, not when the battery was new), so the gauge may be adjusting and you may have some degradation, but the vehicle will still get you there, as long as you are willing to slow down on the longer trips. I have made the return trip with 4 bars remaining, so that should give you an example of how much elevation can alter your energy use.

 

[LEAFfan]

A few days ago, I did my longest trip in the Leaf (without stopping to charge). I drove 68.2 miles from 100% to LBW. Before departing, I reset the Energy Economy screen (on the dash, not the touch screen), as well as the trip meter, and I averaged 4.2 mi/kwh for the trip. The outside temperature was about 45 degrees F, and my battery temperature bars raised from 4 to 5 during the trip. This was my route: http://goo.gl/maps/jBAVm

How much farther could I have gone? Any way to tell how much my battery has degraded, or how much energy I did not have available due to the cold temp? FWIW, I have had my Leaf for 11 months and at the time of this trip I had about 10,700 miles on the car.
Thanks!

How much farther you could have driven also depends on your driving techniques. For instance, if I were driving at the end of your route and I stayed on city streets, I would have been able to drive at least another 15 miles before VLBW at normal street speeds (including coasting). To increase that, you just need to drive slower, time your lights, and accelerate very slowly. After VLBW, there's at least another 5 miles until Turtle, again, depending on how you drive.

 

[ELROY]

A few days ago, I did my longest trip in the Leaf (without stopping to charge). I drove 68.2 miles from 100% to LBW. Before departing, I reset the Energy Economy screen (on the dash, not the touch screen), as well as the trip meter, and I averaged 4.2 mi/kwh for the trip. The outside temperature was about 45 degrees F, and my battery temperature bars raised from 4 to 5 during the trip. This was my route: http://goo.gl/maps/jBAVm

How much farther could I have gone? Any way to tell how much my battery has degraded, or how much energy I did not have available due to the cold temp? FWIW, I have had my Leaf for 11 months and at the time of this trip I had about 10,700 miles on the car.
Thanks!

How much farther you could have driven also depends on your driving techniques. For instance, if I were driving at the end of your route and I stayed on city streets, I would have been able to drive at least another 15 miles before VLBW at normal street speeds (including coasting). To increase that, you just need to drive slower, time your lights, and accelerate very slowly. After VLBW, there's at least another 5 miles until Turtle, again, depending on how you drive.

LEAFAN, you live in Phoenix and still managed all those remarkable range feats?

 

[TonyWilliams]

Right, at that temperature, we can expect about 6% less usable battery capacity per Tony's chart (1% for each 4 degrees below 70 F).

Actually, Tony's chart does not tell you how much battery capacity you lose with temperature. Rather, it tells you how much range you use with temperature. While battery capacity does drop with lower temperatures, other factors also reduce range when the temperature drops and we do not have an accurate means to distinguish between these different effects.

What other factors to new battery. This data was derived by driving a new car with no heater on, in the cold, to turtle.

 

[NYLEAF]

Thanks for the responses, everyone.

According to Carwings, I used 16.2 kwh over 67.3 miles. I actually drove 68.2 miles, but from what I understand, this difference is normal. Is the amount of energy used from Carwings correct?

 

[edatoakrun]

Thanks for the responses, everyone.

According to Carwings, I used 16.2 kWh over 67.3 miles. I actually drove 68.2 miles, but from what I understand, this difference is normal. Is the amount of energy used from Carwings correct?

When you say you "actually drove 68.2 miles" is that from your dash odometer, or from another source? the "normal" discrepancy between dash odometer and CW is usually reported as ~2.5% for LEAF owners with stock wheels and new tires with full tread, slightly greater than the amount you saw.

16.2 kWh may be consistent with all your other kWh use reports, but only "correct" in that it is the kWh amount used to calculate the "correct" nav screen m/kWh, as well as the dash m/kWh which are "incorrect" with the same discrepancy of ~2.5%, apparently based on the same under-reported CW odometer miles.

But since that 16.2 kWh reported by your LEAF that may have been consistently used for all your energy use reports is suspect, IMO, none of these sources can answer the question of how many kWh your LEAF actually used.

 

[LEAFfan]

A few days ago, I did my longest trip in the Leaf (without stopping to charge). I drove 68.2 miles from 100% to LBW. Before departing, I reset the Energy Economy screen (on the dash, not the touch screen), as well as the trip meter, and I averaged 4.2 mi/kwh for the trip. The outside temperature was about 45 degrees F, and my battery temperature bars raised from 4 to 5 during the trip. This was my route: http://goo.gl/maps/jBAVm

How much farther could I have gone? Any way to tell how much my battery has degraded, or how much energy I did not have available due to the cold temp? FWIW, I have had my Leaf for 11 months and at the time of this trip I had about 10,700 miles on the car.
Thanks!

How much farther you could have driven also depends on your driving techniques. For instance, if I were driving at the end of your route and I stayed on city streets, I would have been able to drive at least another 15 miles before VLBW at normal street speeds (including coasting). To increase that, you just need to drive slower, time your lights, and accelerate very slowly. After VLBW, there's at least another 5 miles until Turtle, again, depending on how you drive.

LEAFAN, you live in Phoenix and still managed all those remarkable range feats?

Yeah, when I drove in the Efficiency Rally, I was at 89-90% capacity and still got 50 miles on the last two bars. My first ER was with my '80 VW diesel Rabbit and won easily with 82mpg over a 43 mile course.

 

[surfingslovak]

Thanks for the responses, everyone.

According to Carwings, I used 16.2 kwh over 67.3 miles. I actually drove 68.2 miles, but from what I understand, this difference is normal. Is the amount of energy used from Carwings correct?

Yes, this is very plausible. We calculated total battery capacity of 19.3 kWh, which implies that you had a reserve of about 3.1 kWh when you reached the low battery warning. This reserve normally clocks in at 3.3 kWh usable in 70 degree weather, but if you assume 6% less capacity due to the low ambient temps, then this works out to be spot on: 3.3 kWh x 0.94 = 3.1 kWh.

Isn't he better than that since LBW always comes on at 49 GIDs?

Yes, that's an astute question, and this scenario would apply to a degraded battery, where the amount of available capacity at LBW is held constant. In this case, the whole battery contracts due to cold ambient temps, and there is about 6% less energy available at LBW.

 

[surfingslovak]

Right, at that temperature, we can expect about 6% less usable battery capacity per Tony's chart (1% for each 4 degrees below 70 F).

Actually, Tony's chart does not tell you how much battery capacity you lose with temperature. Rather, it tells you how much range you use with temperature. While battery capacity does drop with lower temperatures, other factors also reduce range when the temperature drops and we do not have an accurate means to distinguish between these different effects.

I meant this reference at the bottom. I was peripherally involved and helped Tony link up with a Leaf owner group in Canada for low temperature testing. I'm pretty sure that his data can be taken at face value, and it should be applied to adjust total usable battery capacity. The impact of low ambient temps on rolling resistance and air density will be expressed in lower energy economy figures. As you can see in the calculation above, this approximation appears to work remarkably well.

 

[planet4ever]

Isn't he better than that since LBW always comes on at 49 GIDs?

Yes, that's an astute question, and this scenario would apply to a degraded battery, where the amount of available capacity at LBW is held constant. In this case, the whole battery contracts due to cold ambient temps, and there is about 6% less energy available at LBW.

So you're saying that the algorithm for signalling LBW differs when battery capacity is restricted by temperature instead of by aging? That surprises me. Either way the battery has "contracted"; it's just that one case is reversible, the other not. Why would the LBC be more "generous" about you using the bottom end in the temporary case?

Ray

 

[surfingslovak]

So you're saying that the algorithm for signalling LBW differs when battery capacity is restricted by temperature instead of by aging? That surprises me. Either way the battery has "contracted"; it's just that one case is reversible, the other not. Why would the LBC be more "generous" about you using the bottom end in the temporary case?

That's a good point, Ray. LBW is going to be trigerred at 49 Gids, like always, but a Gid will hold less energy due to low battery temperature. Although a Gid should be a uniform measure of energy derived from a coulomb count, the hall effect sensor appears to be somewhat temperature sensitive. Additionally, the voltage will drop faster on a cold battery, and since Gids are adjusted to match the OCV, they will go down faster than usual and their average energy content will be lower than with a 70 F battery. Depending on the actual discharge curve, we would expect this behavior to be more or less uniform across the entire SOC range. With a degraded battery, we know that it does not charge to 281 Gids anymore, but the LBW is still triggered at 49 Gids, which will skew the percentage of usable versus total available energy. This will not be the case with a cold battery, which does not have any permanent degradation, and would hold close to 21 kWh usable energy at room temperature.

 

[NYLEAF]

Thanks for the responses, everyone.

According to Carwings, I used 16.2 kWh over 67.3 miles. I actually drove 68.2 miles, but from what I understand, this difference is normal. Is the amount of energy used from Carwings correct?

When you say you "actually drove 68.2 miles" is that from your dash odometer, or from another source? the "normal" discrepancy between dash odometer and CW is usually reported as ~2.5% for LEAF owners with stock wheels and new tires with full tread, slightly greater than the amount you saw.

16.2 kWh may be consistent with all your other kWh use reports, but only "correct" in that it is the kWh amount used to calculate the "correct" nav screen m/kWh, as well as the dash m/kWh which are "incorrect" with the same discrepancy of ~2.5%, apparently based on the same under-reported CW odometer miles.

But since that 16.2 kWh reported by your LEAF that may have been consistently used for all your energy use reports is suspect, IMO, none of these sources can answer the question of how many kWh your LEAF actually used.

68.2 miles was from the dash odometer. I always reset both the Energy Economy and one of the two Trip meters.

 

[surfingslovak]

IMO, none of these sources can answer the question of how many kWh your LEAF actually used.

Yes, let's ask the Mayans. :ugeek:

 

[edatoakrun]

Thanks for the responses, everyone.

According to Carwings, I used 16.2 kWh over 67.3 miles. I actually drove 68.2 miles, but from what I understand, this difference is normal. Is the amount of energy used from Carwings correct?

When you say you "actually drove 68.2 miles" is that from your dash odometer, or from another source? the "normal" discrepancy between dash odometer and CW is usually reported as ~2.5% for LEAF owners with stock wheels and new tires with full tread, slightly greater than the amount you saw.

16.2 kWh may be consistent with all your other kWh use reports, but only "correct" in that it is the kWh amount used to calculate the "correct" nav screen m/kWh, as well as the dash m/kWh which are "incorrect" with the same discrepancy of ~2.5%, apparently based on the same under-reported CW odometer miles.

But since that 16.2 kWh reported by your LEAF that may have been consistently used for all your energy use reports is suspect, IMO, none of these sources can answer the question of how many kWh your LEAF actually used.

68.2 miles was from the dash odometer. I always reset both the Energy Economy and one of the two Trip meters.

Did both your dash and CW report 4.2 m/kWh?

If your CW is updated and working correctly, those numbers should always match precisely, and the nav screen should report ~1.025 X that value, corresponding to the correct (dash) odometer, assuming you have stock tires with full tread. I'd check both the odometer and CW miles against another source to see which of your odometers is showing exactly what % error.

In addition to the daily CW energy use reports, when you access the "rate simulation" page, you get the reported dash m/kWh results from every "trip" (start/stop cycle) without ever resetting either meter. This is the CW report from my trip to the Bay Area last May:

The total at the bottom is Month-to date.