Measured Wall-to-Wheels Consumption

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I have driven exclusively in the B mode since we bought the car May 9th - Almost 4500 miles now. Like you, I'm so used to 'feathering' the throttle on delcleration now that I almost never touch the brakes until I'm down to the 10 or 15 mph range

It just makes more sense to me that using all the regenerative braking I can must be more efficient than using friction braking - I'm glad (but not surprised) to see that your measured consumption proves this

Don
 
Have now covered over 9114 miles (14667km) since early February and here's the latest actual measured energy consumption (from the wall) summary since I started keeping track:

Distance driven with measurements: 8055.5mi (12964km)
Energy consumed: 1916.354kWh
Yielding:
Average 4.204miles/kWh (6.765km/kWh)
Average 0.238kWh/mi (0.1478kWh/km)
Average 23.8kWh/100mi
Average 14.8kWh/100km


All the caveats of my 6/15/12 posting apply.

Don't forget, this is wall-to-wheels which means that the actual energy delivered from the grid to the vehicle has been measured, and the onboard charger inefficiencies are included. This must not to be confused with, e.g., the Leaf's dashboard readout which DOES NOT include the charger.

I had also been keeping track of my Range Remaining each time I fully recharged, and the numbers range from a low of RR = 48mi (77km) to a high of RR = 98mi (158km), with an overall average of RR = 69.9mi (113km). To this day, I am unable to predict what that number will be when I fully charge up the car.

Although I do keep track of whether I was using L1 or L2 (to see what the % of each is), it doesn't mean anything as for all of our local driving L1 would certainly suffice. L2 is simply handy to top up the car quickly for added insurance, or when taking longer trips.

I've been keeping track on a daily basis, dutifully adding up the individual hourly energy consumption increments off my T.E.D. (The Energy Detective), using the Kill-A-Watt (120vac) and a separate kWh meter (240vac) to corroborate the readings. Whenever I charged at a public EVSE or a friend's house, I recorded the exact amounts consumed. Finally, each time I fully charged the car I added up all the preceding partial-charge readings and put them into this spreadsheet.

BTW, the Mitsubishi (Panasonic) L1 EVSE itself consumes 5W or 14VA (miserable power factor), so I've been turning it off when not in use.

The purpose of this exercise was to measure the actual wall-to-wheels motive energy consumption of the iMiEV. Earlier in the year when it was still cool I used the heater very sparingly and during the summer I also barely used the aircon, so the readings are fairly reflective of what the car uses. Now, since I have full confidence in the iMiEV's achievable range, I've recently taken to using its heater with wild abandon, as well as pre-heating the car at every opportunity. This wreaks havoc on my data-taking and I think I'll now throw in the towel on this exercise as my objective has been achieved.

I can categorically say that, on average, my iMiEV goes 4.2miles/kWh (6.77km/kWh). Put another way, my iMiEV has a superb efficiency of 0.238kWh/mi (0.148kWh/km) in roughly a 50/50 mix of city/highway travel. :geek:
 
JoeS said:
Average 4.204miles/kWh (6.765km/kWh)
Average 0.238kWh/mi (0.1478kWh/km)
Average 23.8kWh/100mi
Average 14.8kWh/100km
Does tire pressure from stock to 55 psi have a big impact? I haven't measured my tire pressure yet, but I'm running on where they were at the dealer. I also use coasting and regen like they should be used, but I have a tough time hitting 4 mi./kWh. I average about 3.5 mi./kWh. I drive 45 mph for 10 straight and mostly level miles. My highest RR was 82 miles, but I float around 70 miles RR, and my furthest one-charge distance was 72 miles. This is all without any HVAC use in ~70 degree weather. I can drive 6 miles before losing my first bar on a full charge. I haven't yet done a calibration (<2 bars to full).
 
PV1 said:
Does tire pressure from stock to 55 psi have a big impact? I haven't measured my tire pressure yet, but I'm running on where they were at the dealer. I also use coasting and regen like they should be used, but I have a tough time hitting 4 mi./kWh. I average about 3.5 mi./kWh. I drive 45 mph for 10 straight and mostly level miles. My highest RR was 82 miles, but I float around 70 miles RR, and my furthest one-charge distance was 72 miles. This is all without any HVAC use in ~70 degree weather. I can drive 6 miles before losing my first bar on a full charge. I haven't yet done a calibration (<2 bars to full).
PV1, if you drive 45mph without leadfooting you should be able to achieve well over 4miles/kWhr, since speed is the primary mileage-robber. Try never letting the red needle get out of the green zone on the power meter and coast wherever possible. A fully-charged RR of 82 is quite good and was probably around 5 miles/kWhr if you had measured your input. Based on my experience with my Gen1 Honda Insight, I personally believe that my running 60psi helps significantly but I have yet to be able to quantify this. Realizing that Mitsubishi specifies 36psi and a tire maximum sidewall rating is 51psi, I cannot recommend otherwise. Have fun!
 
benswing said:
Of 439mi tracked I used 155.1kWh to charge giving me:
2.83mi/kWh
353Wh/mi on average

JoeS, recently the "elephant in the room" has been called out as being unlikely. Apparently Lithium Ion batteries may last longer than estimated.

Excerpt: ”Lithium-ion batteries should perform better because they have fewer impurities,” he said. “So the degradation will not be as fast.” He added that electronic battery management is simpler and more reliable if material quality is more consistent from cell to cell."

http://www.designnews.com/document.asp?doc_id=261882&cid=NL_Newsletters+-+DN+Daily&dfpPParams=ind_184,industry_auto,aid_261882&dfpLayout=article&dfpPParams=ind_184,industry_auto,aid_261882&dfpLayout=article&dfpPParams=ind_184,industry_auto,aid_261882&dfpLayout=article

Wow, benswing, that's quite a mouthful! What did you mean that I had been "called out as being unlikely" and what does battery lifetime and that article you referenced have anything to do with energy consumption?

-----------------------------------

EDIT 16 May, 2013: I had completely misunderstood what benswing was saying and apologize for the above remark. A new thread has been created to discuss Operating Costs, as that was the context of a previous post that benswing was referring to:

http://myimiev.com/forum/viewtopic.php?f=9&t=1554

-----------------------------------

I've published the summary spreadsheet of all the data I took last year and be happy to share all the detailed backup with anyone interested as I literally measured every single watthour my iMiEV consumed. Although my wife's driving is conservative, I consider my own driving as being a mixture ranging from enthusiastic to hypermiling, primarily determined by how far I'm going.
 
joev said:
7/31/12
Not a lot of miles yet but this is what I have so far:
428 miles (689km)
79kWh used
80% of the driving is 20-35 mph (32-56 kmph).

Average 5.4miles/kWh (8.7km/kWh)
Average 0.185kWh/mi (0.116kWh/km)
Average 18.46kWh/100mi
Average 11.56kWh/100km

8-31-12
Status quo, all my averages are just about the same as last month.
730 miles (1175km) lifetime
134kWh used lifetime

I am now driving in "B" mode (was driving in "D" and "Eco" in the above stats) and /I can see a slight increase in efficiency.
I would not call it a hyper-mile technique but instead of just coasting to a stop I control the braking (slowing the car down) by adjusting the pressure on the accelerator pedal. If I need a greater stopping distance I keep some pressure on the pedal; less stopping distance I ease off the pedal and get more regen.

I keep a monthly and cumulative lifetime average so I will report next month if the "B" mode makes any difference.

9-30-12
And the winner is......B mode. It did make a slight improvment overall.
Averages for the month:
Average 5.7miles/kWh (9.17km/kWh)
Average 0.176kWh/mi (0.109kWh/km)
Average 17.6kWh/100mi
Average 10.9kWh/100km

1303 miles (2097km) lifetime
235kWh used lifetime

Update:
3237 miles (5208km) lifetime
605 kWh used lifetime
Average 5.4miles/kWh (8.6km/kWh)

Still LOVING it!
 
Re the phrase from Benswing --

"JoeS, recently the 'elephant in the room' has been called out as being unlikely. Apparently Lithium Ion batteries may last longer than estimated...."
which Joe took a bit of objection to:

I THINK I might be able to clear up some confusion and misattribution.

The "elephant in the room" was MY phrase, not Joe's, in my previous post here.
I had used it to refer to the potential hidden cost per mile of amortizing potentially high battery replacement cost (with possibilities of having to pay $10,000+ replacement costs in amortized over 100,000 miles).... I dragged that sideways into the wall to wheels consumption discussion as indirectly relevant in that our really attractive looking out-of-pocket per mile power consumption costs had that hidden aspect.
So if there's correction due (in the sense of longevity looking better than expected per beswing's post, or a slap on the wrist for bending off-topic, it's me, not Joe, or benswing who should get those. ;)

Alex
 
Alex, thank you for the clarification and, benswing, sorry for my misunderstanding.

We have other threads for addressing 'true' vehicle operating costs.

Let's keep this thread for people posting their actual wall energy use per distance traveled, as it's interesting to see if there is any trend for us 'real' users.
 
Acensor, thanks for clearing that up. Sorry if I offended someone. Since someone brought up the battery replacement concern, I wanted to share that article.

I'm with JoeS in terms of wanting to see trends in usage. I've been tracking the usage of my Zero S for over a year and now have a good sense of range based on speed and temperature. Haven't had my iMiEV long enough to get the same info, yet.
 
The Operating Cost discussions previously on this thread have been moved here:

iMiEV Operating Costs

I hope that doing this will provide us with continuity on that interesting subject while maintaining this thread for the collection of actual measured wall-to-wheels iMiEV owners' experience. Thank you for your indulgence.
 
My backwoods approach to measurement has been to just time charging sessions and do the math.

I upgraded to the 12a charger using 110-120V. I have been using Hours x 1.44 to calculate kw drawn from the grid.

With that method, after a little over a month and 811 miles we are averaging 288 w/mile. 3.47 mi/kw.

I took a closer look at my power bill and we average $.083/kw. So we are spending 2.4 cents per mile.

After the first week, we quit feathering the throttle and not using A/C. I still hypermile going into town downhill, pretty sure the wife just keeps her foot in it.
 
More quantitative data from a Belgian study of European-spec i-MiEVs, discussed here:

http://www.plugincars.com/belgians-measure-ev-efficiency-129078.html

Their five sample vehicles over a two-year period averaged a pretty dismal wall-to-wheels of 293.16wh/mi for only 49,253 miles total.

This study confirmed what we've suspected: roughly half of the battery energy is "lost" to non-motive parasites, primarily the heating system. So, the faster we go the less time we allow those parasites to eat into the battery and the better the wall-to-wheels efficiency ...now, if we could just solve the aerodynamic drag problem...
 
Hi,

Well 295 wh per mile is not wonderful but I guess it sound accurate if you drive like a ice car.

I think you can do a little better then that I can get about half that in the summer driving carefully.

If I eyeball my canion consumption for the last 1000 km it looks like an average of 280 wh/mile so I would have to say my year average has to be less then that.

Maybe 295 is a little on the high side for an entire year average.

Don......
 
Small update to my last post.

Was super cold this morning -16 deg C

In the afternoon returning home it was -9 Deg C

I started the car and put the heat on max and pressed the max button. For about 5 minutes not driving while i fiddled with canion errors. then put the fan on high and took off max and started home. Had trouble with canion so i'm not sure how much of the initial heatup was logged maybe half anyways...

10.9 km distance ave speed 24 KPH.

2954 watthrs out and 116 watthrs regen (4%)

414 WH/mile but I was really totally toasty, Just as comfortable as an ICE.

My pack was at 70 % starting so what the heck. Somedays it's nice to be an energy pig......

Don.....
 
I've had my iMiev for a couple of months now and I have done just shy of 4,000 kilometres so around 2,500 miles or so.
I have logged data for most of that time and so far my best has been 150 Wh/km or about 240 Wh/mi.
That was not quite hypermiling but it was consciously driving economically in a relatively flat area.

My worst was 210 Wh/km or 336 Wh/mi which was driving at night over steep hills with high beams on and heater cranking flat out. I was also running late and driving quite aggressively using full power up hills etc. Pretty much worst case scenario.

My average is 180 Wh/km or 288 Wh/mi which is a mix of hypermiling when I go to town and when I am going to work which is close I will use aircon or heater and not worry too much.
Also I live at the top of a steep hill on a gravel road....my work is near sea level and my house is at 900 feet elevation and the last 400 feet or so of climb is done in the last half mile to the house so a LOT of my commute is heavily affected by hills.
My trip to town involves going down to 200' turn climbing again to 1300' then dropping to sea level.
The alternative is either a climb to 2000' then drop to sea level or a straight drop to sea level with a much longer trip around the hills.

Where I live retail power is $0.28/kWh so I average around $0.05/km or about $0.08/mi...
My Volvo 240 was costing about $0.25/km....but the only times I have used it since buying the iMiev have been when I wanted to tow and one time when someone unplugged the car ten minutes after I plugged it in because they wwanted to use the powerpoint......And they know not to do that again!!!
 
carnut1100, thank you for the update and specific data. With all that hydro and the windpower farm on the northwest side of your island, I'm surprised your energy price is so high. What do you use to monitor your input kWh and whereabouts are you located, as so much of Tasmania is hilly? As an aside, I spent a wonderful few months ten years ago in your winter living on my boat in Lindisfarne across the Derwent from Hobart.
 
I'm in the hills about half an hour out of Hobart.

There is a bit of ill feeling about our power prices.......a few years ago Hydro (which was the state government owned sole generator) was split up into Hydro which generates power and sells it to Aurora who sells it to consumers and pays Transend to move it over the lines.......three sets of management and three individual government owned businesses that have to show a profit each year!

We also have the Basslink cable to the mainland and in technicality we sell most of our hydro and wind power to Victoria as "green power" and buy coal fired power from them. Which means that we still pay the carbon tax on our power....

Home solar has exploded recently and a few months ago they cancelled the 1:1 feed in on home renewable systems. Existing systems and those who had signed installation contracts have 1:1 for five years then they will join all Ne. Installations where they get a wholesale $0.08/kWh feed in....
I have a signed contract so I get the five year grandfather arrangement and my panels go up in a couple of weeks, 5kW of them.
When the 1:1 feed runs out in 5 years I'm getting batteries and a backup generator and they can go take a running jump.......
 
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