Range Chart

[TonyWilliams]

There are plenty of anecdotes for the 1 bar/1000 feet.

Honestly, I prefer that is actually BE that, as opposed to 1.23439847239087032kWh per 874.039403809348 feet.

 

[TonyWilliams]

Using one additional bar per thousand feet climbed seems to be about right, at least based on my observations. Keep in mind that this is in addition to whatever energy might be required to cover the distance on the flats.

Check out http://www.mynissanleaf.com/viewtopic.php?f=31&t=5315&start=20#p124074" onclick="window.open(this.href);return false;

Yes, I followed some of that. I believe Leon at Mossy reported not long ago that on his trip, he used two more bars going home, than going to work. It turns out, he's almost exactly 1000 feet higher (lose one going up, and sorta gain one going down).

For me to go to downtown San Diego, it's 20 miles, and 500 feet below. It's tough to figure a full bar without the SOC meter plugged in, but the rule seems reasonable for planning.

 

[planet4ever]

Yes, I think one bar per 1000 feet rise is probably a decent rule of thumb. The part that may be wrong, though, is your guess, Tony, that regen is 50% efficient. I know there are some people on this board who seem to be adamant that it coluldn't be anywhere near that much, but others have reported results much higher than that. One person (I've forgotten who, but he lives high in the mountains) claims to be getting 80%. I really doubt it could be that good, but I'm ready to accept something halfway between 50% and 80% - say 67%. If that is what it is, your rule of thumb would become one bar gained for every 1500 foot drop (minus, of course, the bars lost for your travel).

Look at mogur's numbers a few posts up in this thread: 2 bars for a 23 mile commute with a 1400' drop; 6 bars getting back home. Based on your thousand foot rule, his 6 bars would be about 4.5 if the commute were flat. A 2000 foot/bar rule for the drop would mean he would only gain 0.7 bars, yielding 3.8 bars used for the morning commute instead of the 2 he reported.

Of course, there is a lot more to answer for there than whether regen is 50% efficient. We know it has to be less than 100% efficient, and even 100% would yield 3 bars in the morning. Let's say he actually uses 5.1 bars getting home. and 1.4 of that is due to the climb, leaving 3.7 for the flat-land equivalent. At 80% efficient regen, he would gain 1.1 bars in the morning, for a net of 2.6. At 50% regen he would gain only 0.7 for a net of 3.0 bars.

Neither matches mogur's results, so there must be other factors at play here. However, those results do suggest a very high regen efficiency.

Ray

 

[DaveEV]

Look at mogur's numbers a few posts up in this thread: 2 bars for a 23 mile commute with a 1400' drop; 6 bars getting back home. Based on your thousand foot rule, his 6 bars would be about 4.5 if the commute were flat. A 2000 foot/bar rule for the drop would mean he would only gain 0.7 bars, yielding 3.8 bars used for the morning commute instead of the 2 he reported.

Keep in mind that if mogur's hills are on the highway and speeds are high enough that he isn't using regen on the way down (either coasting or slight power), the discrepancy between going up hill and downhill will be less.

 

[TonyWilliams]

there must be other factors at play here. However, those results do suggest a very high regen efficiency.

Ray

One obvious difference is that the firmware doesn't add fuel bars with the same parameters as it takes them away.

The SOC meter that several of us now have will net some good data in the weeks and months to come.

 

[abasile]

Keep in mind that if mogur's hills are on the highway and speeds are high enough that he isn't using regen on the way down (either coasting or slight power), the discrepancy between going up hill and downhill will be less.

Very true. Actually, I would predict that on gentler descents where no regen is needed and the descending speed is similar to the ascending speed, you will save approximately one bar for every thousand feet descended (versus driving the same distance and speed on flat terrain). Making a round trip on a gently sloped section of road, there should be little net loss due to the elevation changes.

In calculating the efficiency of regen, what you have to look at is the amount of kinetic energy captured and stored in the battery, not including losses due to aerodynamic drag, rolling resistance, keeping the car turned on, and climate control. Given a particular descent, we can easily calculate the gravitational potential energy. We can also approximate the amount of energy used to keep the car moving as the energy cost of driving a given distance and speed on flat land.

On our 5000' descent, we average probably 45 mph over 16 miles, and pick up very roughly 1.5 bars of regen (call it 2.5kWh). Assume the potential energy is 1.37kWh/1000', or 6.8kWh total. At 0.2kWh/mile, we use 3.2kWh to go the 16 miles. That leaves 3.4kWh to be consumed by braking. Assuming only regen braking and no friction braking, that would give us a regen efficiency of very roughly 2.5kWh/3.4kWh, or 74%. This is where we need an SOC gauge for more precision!

 

[planet4ever]

One obvious difference is that the firmware doesn't add fuel bars with the same parameters as it takes them away.

Yes, a very good point indeed. Incidentally, though, I don't think the algorithm you have described elsewhere can be quite right. You have said, haven't you, that if you turn the car off with a partial bar showing, the bar will be gone when you turn it back on? Tonight I was running with one bar, and had been there for one or more miles. (Sorry, I didn't note when I dropped from 2 to 1.) I finally got the LBW, still at one bar, and the guessometer dropped from 10 to 9 and started flashing. 1.2 miles after that we stopped to eat dinner. I fully expected to see zero bars when I powered up after that, but I still had one! We drove (mostly freeway) to LBW+3.5, still with one bar showing, and stopped at a store. This time when I powered back up there were no bars showing. We drove home (no freeway) and got there at LBW+6.0, still no VLBW and the guessometer at 4.

My personal guess is that what is happening when you power up is that half-bar hysteresis, i.e. they display bars as if you were charging, not discharging. I normally assume the first bar is more than half gone when I get LBW, but based on other reports that does seem to vary. Perhaps it was still half "full" when we stopped at LBW+1.2.

Ray

 

[TonyWilliams]

[ have said, haven't you, that if you turn the car off with a partial bar showing, the bar will be gone when you turn it back on?

Maybe... it will be gone. It would have to be below about half full. That's why in the example I used, I split the energy in the fuel bar (I used 81.1%, which is about dead center in the #10 fuel bar).

I'm sure that there is some other funny battery business going on, but for a range chart, you just have to know that your range didn't change if the fuel bar disappears after a restart !!

 

[TonyWilliams]

I'm sure there's mistakes in this, but this is at the request of folks who don't use English measures:

 

[johnr]

There's a typo on the chart on the first post. The image is of version 6a, and it incorrectly starts at 40 mph. In the version 6c pdf file it states 45 mph as it should.

 

[TonyWilliams]

There's a typo on the chart on the first post. The image is of version 6a, and it incorrectly starts at 40 mph. In the version 6c pdf file it states 45 mph as it should.

Thanks for pointing that out.

Yes, I didn't update the image.... yet.

Ok, done now.

 

[johnr]

On second thought, maybe it's supposed to start at 40 mph?? The range difference between the first and second columns is about double the difference between any of the other columns.

 

[edatoakrun]

Good chart, but I believe that the ratio of energy recovery from ascent and descent is close to 80%, rather than 50%, as the chart notes # 1 and 2 state.

See:

Yesterday, I drove the same route again at slightly higher speed with more (still not much) AC use. When I reached my driveway, at 85 miles, I still had (less than) one bar, so I drove until I got the "very low battery" warning and simultaneously lost the last bar, at 91.5 miles. I got home with 93.4 miles, and between 5,500 and 6,000 ft. of ascent and descent, at an average speed of about 40 mph (those last 8.4 miles were up and down a hill at low speed). Since the last 1.9 miles after the "very low battery” warning were at about 20 mph and required about 150 ft. net descent with regen, I was probably still very close to the VLBW point capacity, when I parked.

I will edit with the CW energy use report for this drive, after it shows up.

http://www.mynissanleaf.com/viewtopic.php?f=31&t=5423&p=129484#p129484" onclick="window.open(this.href);return false;

 

[TonyWilliams]

Good chart, but I believe that the ratio of energy recovery from ascent and descent is close to 80%, rather than 50%, as the chart notes # 1 and 2 state.

Lot's of debate on the amount of regen in other threads. Some speculate as little as 30%. I don't think that I'm going to send a new driver to the LEAF off on a trip up a big hill, counting on 80% regen to get them home.

50% is easy to figure. If it turns out to be 63.445498504985409%, hurray, you beat the estimate! I absolutely do not believe it's 80%.

 

[edatoakrun]

Good chart, but I believe that the ratio of energy recovery from ascent and descent is close to 80%, rather than 50%, as the chart notes # 1 and 2 state.

Lot's of debate on the amount of regen in other threads. Some speculate as little as 30%. I don't think that I'm going to send a new driver to the LEAF off on a trip up a big hill, counting on 80% regen to get them home.

50% is easy to figure. If it turns out to be 63.445498504985409%, hurray, you beat the estimate! I absolutely do not believe it's 80%.

I am not suggesting regen is 80% efficient.

I am pointing out that on typical highway driving at 40-55 mph, on relatively gentle grades, you can recover about 80% of the total ascent energy in your descent. This is done by AVOIDING regen (or friction) braking as much as possible, coasting or using light throttle to increase your speed.

I have seen about one bar consumed for each 800 ft. of altitude, and one bar regained for each 1,000 ft. of descent, over a level drive of the same length.

Others have reported a loss of about one bar per 1,000 ft. of ascent (and they may be closer to correct than I am) and a similar 80% of recovery as I have. In fact, the best test would be to charge to 100% at both ends of a long drive with a large altitude change, once in ascent and once in descent. I don't have this opportunity.

I don't know of any reports of 50%.

There is no way I could have driven 91.5 miles with 5,500-6,000 ft. of ascent and descent before hitting VLB unless I was recovering far greater than 50% of ascent energy, on the drive mentioned.

Nor could I have made other trips, such as this one:

So, I drove the Leaf to Lassen Park on Sunday...

My trip from my home (near Oak Run, 2,000 ft altitude) was a little longer, 144.4 miles round trip, about 11,000 ft. total and 6500 ft. net ascent and descent. I recharged from 3 to 12 bars near Shingletown, at a Friend's cabin on the way up. I'd hoped to make the 94.5 miles to the peak and back home on this one charge, taking advantage of the 2,000 ft net descent, but it became clear I'd need to drive well under 50 mph to do so, so I stopped on the way back, charged from 4 to 8 bars, and still had 3 when I got home.

From this and other long climbs and descents I've made, my rule of thumb is now each 800 ft of ascent consumes about one bar, and each descent of 1,000 ft adds one bar. This is assuming road and traffic conditions permit Regen to do most of the braking, and you have 10 bars or less of charge, so full regen is available.

I would not have thought near 80% recovery of ascent energy (by both "coasting" and regen) likely in real-world use on extreme grades, but that's what I'm seeing, and it seems other recent hill climb threads reflect the same experience.

http://www.mynissanleaf.com/viewtopic.php?f=31&t=5022" onclick="window.open(this.href);return false;

 

[TonyWilliams]

I am not suggesting regen is 80% efficient.

I am pointing out that on typical highway driving at 40-55 mph, on relatively gentle grades, you can recover about 80% of the total ascent energy in your descent. This is done by AVOIDING regen (or friction) braking as much as possible, coasting or using light throttle to increase your speed.

Agreed, and logical. But not the point (hyper-mile-ing) for THIS thread. If I drive the car on cruise control, I expect to get numbers closer to 1 bar / thousand feet climb, and half that on the descent.

My car is charging to 100% right now, and I think I'll try a drive to Julian, California, 81.2 miles, 3800 feet gain (400 feet to 4200). I expect to use 6 fuel bars to drive the 40.6 miles at 45mph, minus 4 bars for the 4000 feet elevation change.

Plus, we're experiencing high temperatures here, which will have some negative impact. I should have 2 fuel bars at Julian before I turn off the car (and one fuel bar if I turn the car off, and then back on). The test will be returning the 40.6 miles to return home !!!

I fully expect to maximize coasting, but I will need power to go through several small up hills. It'll be close, and I have a Nissan dealer at the bottom of the hill.

 

[garygid]

The LBW (at about 17.5% SOC (49 raw)) was at the fuller side of the 2nd Old-Bar,
but LBW (still at about 17.5% SOC) is now near the low side of
the 1st (bottom) Bar (new Bar).

So, it would seem that about 1.5 Bars were moved down,
now called "the Reserve" or "the Hidden Bars".

 

[DaveEV]

My car is charging to 100% right now, and I think I'll try a drive to Julian, California, 81.2 miles, 3800 feet gain (400 feet to 4200). I expect to use 6 fuel bars to drive the 40.6 miles at 45mph, minus 4 bars for the 4000 feet elevation change.

Looking forward to the results of this drive - have been contemplating a drive from Encinitas to Shelter Valley on the other side of Julian which at 70 miles will be very challenging considering that going down the other side will require lots of regen to maintain speeds (and possibly a bit of friction brakes).

 

[edatoakrun]

I am not suggesting regen is 80% efficient.

I am pointing out that on typical highway driving at 40-55 mph, on relatively gentle grades, you can recover about 80% of the total ascent energy in your descent. This is done by AVOIDING regen (or friction) braking as much as possible, coasting or using light throttle to increase your speed.

Agreed, and logical. But not the point (hyper-mile-ing) for THIS thread. If I drive the car on cruise control, I expect to get numbers closer to 1 bar / thousand feet climb, and half that on the descent.

My car is charging to 100% right now, and I think I'll try a drive to Julian, California, 81.2 miles, 3800 feet gain (400 feet to 4200). I expect to use 6 fuel bars to drive the 40.6 miles at 45mph, minus 4 bars for the 4000 feet elevation change.

Plus, we're experiencing high temperatures here, which will have some negative impact. I should have 2 fuel bars at Julian before I turn off the car (and one fuel bar if I turn the car off, and then back on). The test will be returning the 40.6 miles to return home !!!

I fully expect to maximize coasting, but I will need power to go through several small up hills. It'll be close, and I have a Nissan dealer at the bottom of the hill.

How'd it go?

Looking at the trip profile, it's clear the total elevation gain is larger than the 3800 ft. from low to high point. Looks like about a 600 ft. descent between miles 12 and 16 alone.

Shouldn't you consider this in your range estimates?

Not very significant on your trip, but I always try to estimate total ascent and descent.

Anyone aware of a resource to do this more easily and accurately than just looking at a topo map and adding it up?

 

[TonyWilliams]

How'd it go?

Stuff came up, so I'll do it Tuesday, Thursday or Friday next week. I'll start a write up in a new thread, also.

Looking at the trip profile, it's clear the total elevation gain is larger than the 3800 ft. from low to high point. Looks like about a 600 ft. descent between miles 12 and 16 alone.

This will have challenges. 14 to 16 miles is the town or Ramona, California. At 400 feet is the town of Poway, California.

Shouldn't you consider this in your range estimates?

I should consider ALL the variables, including heat on the batteries, whatever degradation my battery pack has at 8000 miles, climate control use, every elevation change, payload, and significantly, my own technique.

I always try to estimate total ascent and descent.
Anyone aware of a resource to do this more easily and accurately than just looking at a topo map and adding it up?

That data is in the program I used:

Track statistics:

Distance: 40.55 mi

Elevation gain: 5189 ft

Elevation loss: -1585 ft