IS THIS NORMAL FOR A LEAF?

[ELROY]

I have no idea how Sean (Right Lane Cruiser) from Clean Mpg forum can get 5.9 m/kWh. I am driving, and accelerating as slow as I possibly can. I am taking all the side roads with no traffic, etc. Trying to keep the motor below 10kW when accelerating to even 30mph takes forever (while you are holding up traffic). Sometimes, I wonder if it is better to accelerate at 20kW and get up to speed sooner so you can level off on the throttle. Perhaps all this slow acceleration isn't much better than getting up to speed somewhat quicker?

Sean's economy data (Is he on this forum?)

http://www.cleanmpg.com/forums/showthread.php?t=45554&page=4" onclick="window.open(this.href);return false;

Re: Week of November 5th - November 11th (Nat Avg: $3.50)--------------------------------------------------------------------------------

I couldn't quite make the mark this morning. The relative humidity is fairly high and the windows kept fogging...

34F (29F windchill), 6mph tailwind from the NNE, clear:
•5.9 mpk (169.5 Wh/m) over 14.7 mi --> 198.0 MPGe (Home to work)
Day Total: 5.9 mpk (169.5 Wh/m) over 14.7 mi --> 198.0 MPGe
Tot. Used: 2.5 kWh
Adj. Cost: $0.38
Cost/mile: 2.6¢
__________________
- Sean

ELROY, DGPColorado is correct -- you shouldn't try to compare results from two different drivers in different climates with different terrain and traffic patterns too closely. There are simply too many variables to make it an easy effort.

With that said, I will echo what many others have said on this thread; the more you drive the better you'll get. I'm not unique in managing high miles per kWh numbers (though perhaps I achieve them in somewhat colder temps than most) but my habits behind the wheel are about as far removed from the typical driver as you can get. I've been honing my efficiency skills for many years now and though I've only had an EV for 8 months, energy efficiency is pretty much the same regardless of onboard fuel source.

When it comes right down to it, momentum conservation is the main goal. Ditch cruise control because it aims for constant speed instead of constant power use (a trained right foot is much better). Driving in such a way that you don't need to use regenerative (or worse yet, friction) braking to slow down in most cases and you'll avoid the conversion losses (and just plain losses) associated with those mechanisms. It is always better to keep the vehicle moving than to change the momentum, though you can play games with exchanging kinetic energy and potential energy (useful for getting over hills) which allow changes in speed without as much of an efficiency hit. If you imagine what you would do on a bicycle with no brakes, you'll have the right idea; speed up on flat land and downslopes where it isn't as hard to gain momentum, slow down as you go up hills, speed back up on the other side, coast to stops, and try to time lights by adjusting your speed to the average needed to arrive just as the light turns green.

There is no one magic technique which will get you higher numbers but there are a lot of little things you can do which will add up to big differences. Driving in traffic (which I've done all over the country -- notably LA, Chicago, Atlanta, NY Times Square, Washington DC) requires very different techniques for efficiency than driving on the highway. Most of the techniques have been discussed to at least some extent in the forums here but if you'd like a cohesive picture of the whole spectrum and how they are used together from one person you are welcome to PM me for offline discussion.

Hey Sean, nice to hear your insight. Still amazed at how you can average over 6mi/kWh on over 50 miles of driving some days. All this hypermiling makes perfect sense to me. Just trying to figure out how much acceleration to give it when leaving an intersection. Again..very slow acceleration (2-5kw) and taking forever to hit 30mph vs accelerating at 10-20kw and leveling off much quicker into coast mode, etc.

I just finished testing tonight on this current charge of 80%.

Driving techniques:
Acceleration: Usually under 10wk till the regen disappears around 15-25mph or so, then immediately lifting throttle between 0-3kw or so.

Speeds: Lots of driving 18-20mph in 25mph zones, and 25-30mph in 45mph zones.

In other words, staying awaying from traffic, going as slow as possible to keep the economy gauge as high as possible. Just taking my sweet old time when driving, lol.

So I finished my total test run of 81.3 miles with the following stats:

50-55F temps.
160ft elevation approx.
No significant grades. Essentially level runs everywhere.
44psi tire pressure in all four tires.

80% charge. ECO mode for majority of driving.
61.2 miles for LBW (1 bar showing, 11 miles range indicated)
74.6 miles for VLB warning.
81.3 miles for total test. (same 6:00hr estimated charge time as last test above)
5.4 miles/kWh total economy for the 81.3 miles.

So while I am pleased to have achieved 80 miles, it took some painstakingly slow/careful driving. I am pretty familiar with most of these hypermiling techniques. I have achieved fairly high MPG numbers in my previous BMWs. I have averaged 47mpg in my 335d with a 70mph average on a 28 mile trip (36mpg EPA rating). For this 5.4 mi/kWh test session I tried to pace the traffic lights, and short of running stop signs, tried to conserve momentum. Part of this did include 10 miles of fwy driving (55mph), and probably 4 full throttle sprints to 40mph (road rage, lol). So I could probably have achieved even higher than the 5.4 number.

Sean, I know you were thinking you could get 100 miles on an 80% charge, Is that correct? Or do you achieve that regularly? And secondly, If it is so that a 80% charge is about 18KW usable. Shouldn't a 5.4m/kWh x 18kW run come out to about 97.2 miles? And if so..that is where my concern is. Isn't my 81.3 miles a little on the short side still? I'm wondering if my battery capacity may be a little compromised, as I felt it has been from the day I got the car. Battery temp is always around 5 bars. Never quick charged the car, etc.

I will find out exactly how long it takes to charge the car this a.m. I am assuming it will be somewhere around 5 hrs though. L2 16A EVSE upgrade. Assuming the 6hrs predicted vs 5hrs actual is normal,, and not an indication that my battery is not absorbing a full charge?

 

[surfingslovak]

This type of energy economy is very good for a new LEAF owner in the midst of winter. I'm not the best hypermiler on this forum. I think that title goes deservedly to LEAFfan and N1ghtrider, but like many others, I did a number of science experiments. Here is one of them. I meant to upload it earlier, but perhaps it's still relevant.

Last summer, I commuted to and from work for an entire week on one charge. I wanted to see if I could break the 100-mile barrier in everyday driving with a somewhat degraded battery. I would estimate the effective range loss to be about 8% at this juncture. The metrics from the dash should give you an idea of what I did.

 

[RegGuheert]

So I finished my total test run of 81.3 miles with the following stats:

50-55F temps.
160ft elevation approx.
No significant grades. Essentially level runs everywhere.
44psi tire pressure in all four tires.

80% charge. ECO mode for majority of driving.
61.2 miles for LBW (1 bar showing, 11 miles range indicated)
74.6 miles for VLB warning.
81.3 miles for total test. (same 6:00hr estimated charge time as last test above)
5.4 miles/kWh total economy for the 81.3 miles.

I think that looks pretty good!

On Tuesday I drove 79.4 miles in 50F weather on a FULL charge and arrived home with 12 showing on the GOM and 2 charge bars. My energy economy was about 4.6 mi/kWh for the trip. If you consider I drove about 17 miles on the 12th and 11th bars combined probably 3 miles on the 10th bar before getting down to the 80% level, we travelled a similar distance.

While your LEAF indicated that you drove at a higher efficiency, I'm not sure how reliable that number is. I am a little surprised that you hit LBW with 11 miles showing on the GOM. I usually hit that with between 7 and 10 miles showing.

I will also note that my battery was likely better balanced than yours since I have charged it to 100% and heated the cabin while charging at 100% on several sprecent days. Repeatedly charging to only 80% for weeks or months at a time certainly will reduce your range some, but only until it gets rebalanced. Rebalancing doesn't not seem to happen in a single 100% charge, but often takes several. Running the climate control while charging slows the charging rate, which also seems to improve cell balancing.

 

[RLC]

Hey Sean, nice to hear your insight. Still amazed at how you can average over 6mi/kWh on over 50 miles of driving some days. All this hypermiling makes perfect sense to me. Just trying to figure out how much acceleration to give it when leaving an intersection. Again..very slow acceleration (2-5kw) and taking forever to hit 30mph vs accelerating at 10-20kw and leveling off much quicker into coast mode, etc.

I just finished testing tonight on this current charge of 80%.

Driving techniques:
Acceleration: Usually under 10wk till the regen disappears around 15-25mph or so, then immediately lifting throttle between 0-3kw or so.

Speeds: Lots of driving 18-20mph in 25mph zones, and 25-30mph in 45mph zones.

In other words, staying away from traffic, going as slow as possible to keep the economy gauge as high as possible. Just taking my sweet old time when driving, lol.

So I finished my total test run of 81.3 miles with the following stats:

50-55F temps.
160ft elevation approx.
No significant grades. Essentially level runs everywhere.
44psi tire pressure in all four tires.

80% charge. ECO mode for majority of driving.
61.2 miles for LBW (1 bar showing, 11 miles range indicated)
74.6 miles for VLB warning.
81.3 miles for total test. (same 6:00hr estimated charge time as last test above)
5.4 miles/kWh total economy for the 81.3 miles.

So while I am pleased to have achieved 80 miles, it took some painstakingly slow/careful driving. I am pretty familiar with most of these hypermiling techniques. I have achieved fairly high MPG numbers in my previous BMWs. I have averaged 47mpg in my 335d with a 70mph average on a 28 mile trip (36mpg EPA rating). For this 5.4 mi/kWh test session I tried to pace the traffic lights, and short of running stop signs, tried to conserve momentum. Part of this did include 10 miles of fwy driving (55mph), and probably 4 full throttle sprints to 40mph (road rage, lol). So I could probably have achieved even higher than the 5.4 number.

Sean, I know you were thinking you could get 100 miles on an 80% charge, Is that correct? Or do you achieve that regularly? And secondly, If it is so that a 80% charge is about 18KW usable. Shouldn't a 5.4m/kWh x 18kW run come out to about 97.2 miles? And if so..that is where my concern is. Isn't my 81.3 miles a little on the short side still? I'm wondering if my battery capacity may be a little compromised, as I felt it has been from the day I got the car. Battery temp is always around 5 bars. Never quick charged the car, etc.

I don't know how much of my driving you've followed but if you haven't seen this it should give you some indication of what is possible when keeping speeds to no higher than 43mph in urban traffic (@ 85F):

The above was the trip home after my 14.7mi trip to work at 7.2mpk (@ 69F). I started with an 80% charge and had the car parked for a full workday before driving home. Greater than 7mpk is not that unusual for me during the summer. I haven't actually tried to crack 100mi yet as I'd prefer to make the battery last as long as I can -- I purchased rather than leasing. I've only seen the first battery warning (LBW) once... and it was 0.9mi from my house.

Here's another shot of my drive to work on a 75F morning, again starting at 80%:

At those higher numbers there is actually a 0.2mpk difference between the dash and the console readouts.

I do run higher tire pressure than what I've seen mentioned here, but the real issue is that this car is just plain heavy. At 3400# it is nearly twice the weight of my Insight (1830#) and it takes a while to really get a feel for how to move it from place to place with a minimum of energy expenditure.

I recommend accelerating at 10kW or so -- I kick it up to 20kW for heavier traffic -- but keep an eye out for long distances ahead to gauge changes (traffic, red lights, etc) way before you reach them. The further ahead you see something the less you have to adjust your speed or path to compensate. As I accelerate I actually switch from using the power output meter to pegging targets on the instantaneous energy usage bar on the dash. In other words, I start at 10kW or 20kW, then as I gather speed I start trying to hold onto minimum mpk values -- first 2, then 3, and so on. Once at speed, I target minimums for levels and hill climbing -- in warm weather at moderate speeds I can typically make it up most reasonable hills at 4mpk. On level ground at speeds of 20mph or higher you should be able to target 6mpk or higher with no wind and moderate temps.

For reference in colder temperatures, here's what I did yesterday:

• 5.5mpk over 14.8mi in 33F weather with a 19mph crosswind from the W -- highway driving between 50 and 55mph for 11 of the miles. The rest were urban/suburban at 30-35mph. This was home to work.
  
  
• 5.5mpk over 9.0mi in 30F weather with a 13-18mph crosswind from the W. The first 5mi were 50-55mph on the highway (accelerated on the ramp at 25kW as it is both uphill and short), the rest on urban, 45mph limited roads with that wind at my back. Work to dental appointment.
  
  
• 5.8mpk over 0.4mi in 32F weather with a 14-19mph wind from the WSW. Urban driving to lunch with my wife at a local Burger King.
  
  
• 5.4mpk over 11.3mi in 33F weather with a 10mph cross/headwind from the WSW. Urban driving on roads limited to anywhere from 30mph to 50mph to get back to my house.

After that I charged to 100% to see what would happen in the evening for a trip on the highway to Church and back at lower temperatures. I didn't use anything but 3 fast bursts of defrost for the entire round trip (though I kept the driver's seat heated along with the steering wheel for all my driving yesterday).

• 4.5mpk over 20.4mi in 27F weather with no wind. Highway driving for 17 of those miles at 50-55mph, the rest on 30-45mph limited urban roads. Home to Church. Parked for 2hrs.
  
  
• 4.8mpk over 19.1mi in 21F weather with a 2mph cross/tailwind from the SSE. 1mi of urban driving on 45mph limited roads, the rest on the highway over to a drug store not far from my house.
  
  
• 5.4mpk over 1.1mi on urban to suburban streets back to my house at 30-40mph.

I arrived home with 6 bars showing and the remaining distance shown as 45mi. I had left the house with it showing 110mi, and that dropped down to 87mi when I got on the highway 2mi later. As long as I'm pretty consistent with my driving the range remaining meter seems reasonable, though it gets way off if I have the heater on (never adjusting properly, just dropping two miles for every one I travel).

In warmer weather such as what you have now I target (and usually achieve) 5mpk for highway trips at 50-55mph. In really warm temps (93F) I managed over 5mpk at 60mph with the AC on and the car full of people for over 80mi. I got home at 83mi driven and 11mi remaining IIRC.

I saw earlier in the thread that it was mentioned ECO mode keeps heater power draw down to 2kW or less -- this is true only as long as you don't get down below 20F or so. At 3F it climbed up to 3.5kw at a minimum and wouldn't drop lower no matter what I did. It kept climbing to 4kW then dropping periodically -- a terrible hit to efficiency. When I have to have the heater on (for the family, usually... though in really cold temps I need the defrost and a little heat for myself) I drive in ECO mode to keep the power usage in check, otherwise I drive in D mode using a foot induced zero energy glide any time I need to slow or find a slope steep enough to maintain acceptable speed. As other members here do, I shift to ECO when I want more slowing power and I avoid the brake pedal as much as (safely) possible to avoid friction braking (from which you can recover no energy at all).

Hopefully that gives you a better picture of what the car can do in different circumstances. Your highway numbers and charging times look reasonable to me. Your in town driving seems inefficient but traffic hypermiling is challenging to master. Just use minimum pedal pressure, look far ahead, and if traffic is varying speed, try to hit the average speed so that you don't have to do the accelerator/brake dance with everyone else around you. It's OK to get a rubber band effect with the people in front of you -- the people behind will actually appreciate this if you do it well because they are "dancing" less as well.

 

[ELROY]

As I thought...the 6hrs of estimated charge time took almost exactly 5hrs. (5hr 1min to be exact)
So I am estimating about 16320 watts used (at approx 85% efficiency?)

Surfingslovak, good numbers at 6.0 mi/kWh over so many miles.
And if you had range reduction and still achieved those miles, I really question my battery capacity.
So at 6 hrs estimated, my actual charge time was 5hrs.
Do you remember what your 7hrs estimated actual time came out to? 6hrs?
I assume you started with 100% battery also? Actually the difference between 80% and 100% always seems to be about 1.50hrs estimated charge time (indicated)

What is that PS warning on above the battery bars? Is that the precursor to turtle or something?

Also, what kind of numbers can you get in the active E? I know that car is even heavier than the LEAF.

Driving to work today....25-30 mph...3 miles......I am at my highest average so far. 6.0mi/kWh. I will see how long I can maintain that for. Edit: Drove down the street to Taco Bell, now at 5.8 After driving home from work tonight..driving pretty slow...25-35mph..I am now down to 5.2 mpk

Also, isnt there something that can be deduced in regards to my battery capacity/efficiency numbers?
5.4mi/kWh, 5.0 hrs of charging time to 80%. 81 miles of driving? Does that calculate correctly? Or should I be getting around 97 miles and perhaps missing a few kWh of battery charge available?


Sean,
Incredible numbers.
Very good driving tips. Glad you can share your experience. I think you will find more people with LEAFs on this forum more captivated by the detailed information you give. I think the only way I am getting 7mi/kWh would be crawling across the parking lot at 2mph, LOL.

You are right, with the heavier car, it is sometimes so hard to even feel any power going to the motor, which makes the motor pie chart screen the one I keep on the Nav screen when I am driving. I kind of wish it would always default to that screen. And yes, towards the end, before reaching an intersection, I try to be in the glide mode (little black sliver) as much as possible.

I still dont even see how you can get above 7mi/kWh unless you are doing like 5mph? What kind of speeds were you achieving during that episode? What is the highest efficiency and practical speed to cruise around town on the straights? 25mph/35mph/40mph? And most importantly, initial acceleration from an intersection stop...do you start at 10kw or less? (after regen is used up)

 

[RLC]

You don't want to try to drive at 2mph -- it isn't efficient. Let the car crawl along with no pressure on the accelerator and watch the instantaneous bar -- you'll see it stays pretty low because your auxiliary systems are consuming a significant portion of your energy expenditure. You can get high instantaneous numbers on flat land at low speeds but 18mph is about the lowest I can go and still manage higher numbers while dealing with undulations in the road.

My 7mpk and higher runs all included some driving up into the low 40mph range (43 or so, actually) but I've been able to peg the gauge at 8mpk in 80+F weather at 48mph with just a 5mph tailwind. I normally stay in the mid to upper 30's for around town driving as the speed limits vary between 35 and 45 in most places, and I'll stick right around 30mph if that's the speed limit, varying speed to accommodate terrain. A simple approximation for this is holding very steady on the accelerator so that you slow down a bit going uphill and gather speed again on down slopes. The idea is to keep the energy expenditure pretty even rather than trying to keep the speed too even. This is often called "Driving with Load" (as in the load on the power-system).

Do what you can to "stack the deck" for yourself. I choose routes for least traffic based on time of day and favor lower speed (35mph preferably) two lane roads that allow me to do my thing while letting others get around me easily. Driving efficiently doesn't mean you have to be an obstruction on the road, after all. I'll even go so far as to employ what I call "reverse passing" to help the flow of traffic. It is possible to maintain a lower than average speed on a multi-lane road with light to medium traffic by switching lanes and letting people pass who are approaching from the rear. They don't wait to see if you'll go faster and you don't get tailgated... but you do still drive slower. It is a little thing but makes more of a difference than you might think.

To be clear, it typically takes me 40min or so each direction for my work commute on the non-highway route -- mostly because of the number of lights and stop signs involved, not my lower speeds.

I normally leave from a stop at 10kW but will go up to 20kW if there is heavier traffic. At 10mph or so I start looking to maintain instantaneous numbers (as mentioned in my earlier post).

 

[ELROY]

I actually drove 2.5 miles to work this morning. 50F temp. And average 7.0m/KwH. I was pretty happy. But then I just drove around the corner to Taco Bell, and parked, and drove back to work and my average is down to 5.8 in probably 1/2 mile of very easy driving!

Question: I was running a little 100watt heater from the lighter when I was parked for about 15 minutes listening to the radio. (accessory mode, ignition off). Does the dash economy gauge recalculate actual battery level even when the car is not being driven? So possibly my draw when parked caused the dash economy readout to be recalculated? It would make sense. If you were idling your ICE car, the gas used would reduce your average mpg readout in my BMW.

I'm also quite certain when I first drive to work it is fairly easy to maintain 6.0 m/kWh when cruising between 25-35mph for the 2.5 mile trip. Yet on the way home, and other times it is hard to even maintain 4m/KwH even when driving 30mph or so. It just seems almost impossible sometimes to get high economy and very easy other times under the same conditions....Anyone else notice these distinct changes? I am not running the heater at all. I run high tire pressure, etc.

And lastly, why is it that sometimes you slow down (in ECO) and regen seems pretty aggressive. You can even hear the electronic whine fairly loud at times. And other times, it is so weak I double check to verify that I have it in ECO. The battery is always below 80%, so the car can use the recharging. Is it possible it waits till the battery is warmed up before it will accept heavy regen? Temps are around 50F, and generally seems to stay at 5 bars on the battery temp gauge.

Trying to figure out these inconsistent modes of operation.

Edit: Drove home for lunch...25mph...cruise control...the economy stayed around 4.5. Very difficult to get 5.0. My economy fell from the 7.0 when I started this morning to 5.2! go figure. Could the 12v battery being charged by the Lithium pack caused the computer to recalculate lower? Either way, the steady state economy bar graph seems very low for my miserly driving.

 

[TonyWilliams]

.... I am a little surprised that you hit LBW with 11 miles showing on the GOM. I usually hit that with between 7 and 10 miles showing....

The GOM is the singular epitome of what not to use to compare or calculate range or efficiency data. Here's my customary GOM debate icon:

Like every GuessOmeter discussion, I always wonder how it will end?

 

[TonyWilliams]

Question: I was running a little 100watt heater from the lighter when I was parked for about 15 minutes listening to the radio. (accessory mode, ignition off). Does the dash economy gauge recalculate actual battery level even when the car is not being driven?

Phil reports that those 12 volt DC loads are not measured, but estimated. So, no, it wouldn't know that you're sucking 8 amps.

 

[DaveEV]

Elroy, I'd bet that its slightly downhill on the way to work and slightly uphill the other way. Doesn't take much elevation to get the behavior you're seeing.

 

[TonyWilliams]

You can get high instantaneous numbers on flat land at low speeds but 18mph is about the lowest I can go and still manage higher numbers while dealing with undulations in the road.

I did 10mph and 15mph runs on a virtually flat 2.5 mile circular course at sea level. Both yielded the same economy (you can use the center navigation screen to see economy above 8.0 miles/kWh).

If you shoot for 12mph, you are probably at "n".

 

[ELROY]

Elroy, I'd bet that its slightly downhill on the way to work and slightly uphill the other way. Doesn't take much elevation to get the behavior you're seeing.

I was thinking the same thing. Even though there is no noticeable slope. The trip to work is from east-west, which is toward the ocean. Will research on my Google Earth. Can't be more than a 10Ft elevation drop in the 2.5 mile trip to work.

Edit: Okay, so I just checked Google Earth. My house is at 160ft elevation. My work is at 103ft. So a difference of 57ft over a 2.5 mile range. Its a gradual decline all the way to work. Wonder if this is what is responsible for such a huge difference in economy?

 

[TonyWilliams]

Wonder if this is what is responsible for such a huge difference in economy?

It is that sensitive over such short distances.

 

[RLC]

You can get high instantaneous numbers on flat land at low speeds but 18mph is about the lowest I can go and still manage higher numbers while dealing with undulations in the road.

I did 10mph and 15mph runs on a virtually flat 2.5 mile circular course at sea level. Both yielded the same economy (you can use the center navigation screen to see economy above 8.0 miles/kWh).

If you shoot for 12mph, you are probably at "n".

Indeed -- completely flat is the key. I'm in MN but billiard table flat it is not and at 3400# the car is extremely sensitive to even small undulations. My experience has been that 18mph is fast enough for momentum to give me a buffer that can deal with the slight elevation changes while maintaining a 6+mpk average. On the completely flat sections of my route I agree that 8+mpk is obtainable at 10mph in warm weather. In 3F with no wind I seem to max out at around 6.5mpk or so on the instantaneous readout for sustained travel, so of course the average is lower.

Elroy, keep in mind that aside from elevation changes very short trips are quite inefficient. Your 1/2 mile trip included a substantial power use just to get the car up to whatever speed you attained. Going from one parking lot to another you probably had a stop after reversing from a parking spot, another at the lot exit, and perhaps another before you could turn into the restaurant lot. That's a lot of energy getting the car moving from a stop (or very slow speed) over a short drive. If that 1/2 mile was actually a round trip, double the stops and you've got a horribly inefficient trip.

You could eliminate one of the stops by parking face out when you can pull through a slot, or use gravity for the reversing power. I often park at work on a slope, face out perpendicular to the grade. To park I coast up the hill past the slot, then roll backwards while turning to get into the slot. If I over do the turn I can end up with the nose pointing just a tad downhill, then when I leave I can just put the car into neutral and let it roll out and down the hill.

One more observation here. Lower trip efficiencies affect overall averages more than you expect because the numbers aren't a straight average. It's actually an inverse relationship of energy consumed (just as with mpg computations). The example I use with gas powered cars (with numbers obtainable in my '02 Insight) is a 2mi trip with the first half at 100mpg and the second at 50mpg. You might think the overall average would be 75mpg but it isn't because you used twice as much fuel in the second half as the first. That means the average is actually 66.7mpg. The same relationship exists for mpk calculations.

I recommend recording the average for each trip individually -- then you can see what is really affecting your average. Compute the total yourself using the total distance divided by the total energy used. The energy used for each trip is trip distance divided by efficiency.

Keep up the hard work -- it will pay off with more practice!

 

[TonyWilliams]

The example I use with gas powered cars (with numbers obtainable in my '02 Insight) is a 2mi trip with the first half at 100mpg and the second at 50mpg. You might think the overall average would be 75mpg but it isn't because you used twice as much fuel in the second half as the first. That means the average is actually 66.7mpg. The same relationship exists for mpk calculations.

Interesting thoughts. Thanks.

 

[dgpcolorado]

...Elroy, keep in mind that aside from elevation changes very short trips are quite inefficient. Your 1/2 mile trip included a substantial power use just to get the car up to whatever speed you attained. Going from one parking lot to another you probably had a stop after reversing from a parking spot, another at the lot exit, and perhaps another before you could turn into the restaurant lot. That's a lot of energy getting the car moving from a stop (or very slow speed) over a short drive. If that 1/2 mile was actually a round trip, double the stops and you've got a horribly inefficient trip...

Good point. I find that the mileage meter doesn't give meaningful results on short trips. It takes a few miles before it settles down and the numbers start to make sense.

Because 2.5 miles is too short a trip to get useful numbers—figures that can be compared to those of us who are looking at 10-70 mile trips—my suggestion for ELROY is to accumulate mileage for several trips or days and see what the numbers say. The mileage will still be lower than if he just drove that distance straight because on/off cycles will cause a hit, but it should give a more useful driving efficiency than looking at a 2.5 mile result. Extrapolating from a very short trip mileage just isn't practical guide to how well car and driver are doing IME.

 

[ELROY]

Yes, absolutely true how horrible economy is hard to make up for.

Say you drive a ICE vehicle up a steep hill, 10 miles up, and 10 miles down.

On the way up you average 10 mpg..
On the way down you average 100mpg.

You would think your average for the total 20 miles would be around 50mpg or so.

Nope...Even if you coasted with the engine off down the hill, your total trip can't be more than 20mpg.

On the other hand, kind of reached a milestone in my car collection today. I just sold my Grand National today. Was building the engine to race specs, and then it kind of sat around for 15yrs. I remember the thing could really suck up the gas though. Kind of a relief to get rid of it and make more room on the driveway. I hated parking 3 wide and worrying about opening the door, etc. And the LEAF will NEVER have to park on the street now. I'm quite certain my next car will be another BEV anyways.

 

[Ingineer]

On 12v loads: The DC-DC converter is ultimately powering them, so even though the energy screen wont show the extra loads, it will come out of your traction pack. This means the LBC is clocking it out, so your consumption figures will higher than normal for a certain type of driving. So if you sit in a parking lot, even with the Leaf not in ready drawing from the battery (bad idea BTW), when you DO go ready, the DC-DC has to recharge the 12v, so there's no free lunch.

-Phil

 

[ELROY]

On 12v loads: The DC-DC converter is ultimately powering them, so even though the energy screen wont show the extra loads, it will come out of your traction pack. This means the LBC is clocking it out, so your consumption figures will higher than normal for a certain type of driving. So if you sit in a parking lot, even with the Leaf not in ready drawing from the battery (bad idea BTW), when you DO go ready, the DC-DC has to recharge the 12v, so there's no free lunch.

-Phil

Yes I figured the 12 battery charging would be monitored. I wonder if the 12v battery ever had a bad cell or self discharge if the diagnostic system would pick it up right away.

Also, when sitting on my break listening to the radio I usually have it only on accessory position so no other gauges are lit up. I'm assuming the current draw is pretty nominal. On the other hand, come summer time, I'm sure I will run the A/C sporadically while waiting in the car. I was wondering what voltage the climate control system uses. On one hand, I'm sure its not 12volts powering a 4.5kw heater system. Yet on A/C, a 300 watt draw or so might only be about 25 amps or so. Does the heater actually use the battery pack high voltage with the orange wires? The a/c compressor doesn't have high voltage orange wires going to it correct? And I would assume the ventilation fan is 12volts? So perhaps the Climate Control system works on a combination of high and low voltages? Again, I would assume only the heater element would have to be high voltage.

 

[Ingineer]

Unfortunately there is no diagnostic system on the 12v battery that will detect a shorted cell. I'm sure you'd find out pretty quickly when your Leaf refused to go ready though!

Both the A/C compressor and the eberspacher heater are run from the high-voltage. Only the climate control fan is 12v. BTW, the heater is a 6kW unit, so it can draw up to that, it's not limited to 4.5kW.

-Phil