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Discussion Starter #1


Looking for some input on a little experiment I have started to make sure I'm going at this the right way.

I bought a Kill A Watt Edge. For the next month, I'm going to do nothing but level 1 charging at home and run it all through the Kill A Watt. I'm going to track my mileage and write it on a chart in the garage at the end of each day. At the beginning of the next day, after charging all night, I'll write down how many kWh it took to charge and what the Kill A Watt says it cost me based on the average rate of 10.2 cents per kWh from the past 8 months.

My thinking is, I should be able to calculate a cost per mile from this. I should also be able to see how much my Smart is adding to our electric bill each month.

I know I could replace my ClipperCreek level 2 charger with a ChargePoint but doing it through the Kill A Watt seemed like a cheaper option.

Does anyone see any issues with my approach to what I'm trying to do? Am I overthinking it?


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Your true cost per mile would also include wear and tear items (tires, dessicant cartridge, brake fluid), but if you're just interested in energy cost per mile, you should have it nailed.
 

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Discussion Starter #4
For now I'm just looking at electricity cost. But that's going to take me a while to build up a record. Plus, to get some sort of long term numbers, I need to keep doing this through the winter and summer. So we'll see. But then I'll have to add in all maintenance and repairs down the road.


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2014 Cabriolet bought in Sept 2016 with 6,470 mi
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I've been keeping track of my trips and electricity usage since I got my 2014 Cabriolet with 6470 miles on it in September of last year.
After 3500 miles, avg mi/KWh is 4.9 (actual draw as recorded by my Kill-A-Watt) and cost per mile is around 2 cents.
I live in the Chicago area and have been able to get over 100 mi/charge for every charge since the end of May with a top of 120
 

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@DealMeln
I'm between 2 and 3 cents per mile. I use the AC and I don't always drive with a light foot.

So does your computer tell you that you have 100 miles when you start? Mine seems to cap off at 90. If I drive real conservatively and don't use the air or heat, it will sit at 90 for several miles. Does yours do that or does it start off at 100.

As a side note, mine used to always say 68 or 70. After they replaced my high voltage battery, it went up to 90.


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@emailchrishall
I don't use the AC - I've got the convertible and I drive pretty conservatively, have an 8 mile round trip commute and don't drive a lot on high speed roads.

I think they limit it to 90 on the trip computer. Mine has never read more than that even when it is obvious early on that I will get well above 100. With a full charge it will stay 90 for between 10 and 13 miles. The SOC doesn't usually move off of 100 for 7 or 8 miles in the summer on a full charge either.
 

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So have you actually driven it 100 to 120 miles on a charge or are you estimating that's what you could attain? Best I can do on mine after driving them for 2+ years is 90 miles. Now if I only drove in my community stop and go at 25 mph regenerating half the time, maybe I could hit triple figures.

Len
2014 EV Coupe 12,500 miles
2014 EV Cabriolet 1,250 miles
 

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Len

It's actual miles driven. My 8 mile RT commute is a max of 35mph. My health club is a 15 mile RT with a max of 45mph. Those are my most common trips (I do most of my shopping as part of those trips as well). The key it seems is to NOT use the regenerative braking - I look ahead and coast a lot to stop lights, stop signs whenever possible. The less you have to do any braking, the better your range will be. I could probably get 130+ with low rolling resistance tires like I have on my 2000 Honda Insight.
 

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Discussion Starter #10
That's pretty amazing. The most I have done was 90 miles. I was right at zero on the gauge.


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I don't belong to a health club - maybe that's my problem. :)

I do coasting when I can too, but I'm not sure whether coasting or regeneration is more effective/efficient. I can see coasting down from say Pike's Peak, but you still have to pay your way in terms of energy to get up there. You can't go downhill both ways. :)

I don't see any way that I could ever get close to the numbers you are talking about.

Len
2014 EV Coupe 12,500 miles
2014 EV Cabriolet 1,250 miles
 

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I have now had my 2014 Cabriolet for over a year and here are the basic stats:
Round trips taken: 307
Miles Driven: 3,392 (started with 6,470, ended with 9,862)
Times Charged: 39
KwH used: 673.7 (Kill-A-Watt), 649.6 (car)
Electricity Cost: $70.30 (added up Kill-A-Watt usage times electricity costs charged per KwH on my monthly bill)
Cost/mile: $0.021
Miles/Charge: Avg: 87.0; Low 50.1; High 120.0 (12 over 100 miles total)
 

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I've been at this since May 2014 (38,550) and in Atlanta using ChargePoint and home, I've strongly average 2.01 cents per mile due to a lot of free stations. So yes, get a Chargepoint card and they give great usage numbers.

Again, there's insurance, road tax penalty ($200), tires, windscreen wipers, annual mercedes charge (approx $200), BAP, etc but my total cost of operating is less than $.14 per mile.


Leaves plenty of $$ for drone parts ;)
 

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Discussion Starter #14
I've been at this since May 2014 (38,550) and in Atlanta using ChargePoint and home, I've strongly average 2.01 cents per mile due to a lot of free stations. So yes, get a Chargepoint card and they give great usage numbers.

Again, there's insurance, road tax penalty ($200), tires, windscreen wipers, annual mercedes charge (approx $200), BAP, etc but my total cost of operating is less than $.14 per mile.


Leaves plenty of $$ for drone parts ;)


If I had it to do over, I would get a ChargePoint. But the customer service at ClipperCreek is so awesome.


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I use chargepoint for my 2017 smart - works really well.

I also use the app ‘My EV App’ to track my trips and maintenance costs, a trip for us can also be a days worth of driving. What I like so far about the app is that it compares my smart trip electricity costs to my gasoline car so that I can always see how much I saved per trip, per month, per season and lifetime.

It also gives me a number representing the distance I can travel for each 1% of battery, they refer to it as d%b. So if the smart gets a maximum 160klms (100 miles) per charge, they say the max d%b would be 1.6 (1.6*100% of battery is 160 klms). I can relate to that better than kWh lingo or MPGe. My current average is 1.20 which means if I had a full charge, I’m likely to get real world results of 120 kilometres, I’m trying to get to 1.40 but it’s now too cold for that.

We’ve only had our smart for a few weeks, but we’re going to keep recording our trips for the next year through all the seasons, then we will know our savings compared to our Rav4 Hybrid and what our electricity costs were. Our current savings after 3 weeks is $74 for 650 klms.

Cheers.
 

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I have now had my 2014 Cabriolet for over two years and here are the basic stats for years 1 and 2:
Round trips taken: 307 and 257
Miles Driven (started with 6,470): 3,392 and 2468
Times Charged: 39 and 28
KwH used: 673.7 and 485.3 (Kill-A-Watt), 649.6 and 439.2 (car)
Electricity Cost (added up Kill-A-Watt usage times electricity costs charged per KwH on my monthly bill): $70.30 and $52.60
Cost/mile: $0.021 both years
Miles/Charge: Avg: 87.0 and 88.1; Low 50.1 and 55.6; High 120.0 and 120.8; 12 and 11 with 100+ miles total driven before charging

mpg equivalent (using lowest cost price per gal regular in my area at the time of charging): 123.5 for year 2 - I didn't keep track of the cost/gal of gas until well into year 1


The only other cost was $6 for a turn signal bulb that went out.


Overall another very good year. Less driving I think due to getting given two Great Danes (one in April the other in June) and spending more time at home instead of going places. Neither of them will fit in the Smart. I got a 2007 Honda Element for taking them around in - it's the perfect dog car.
 

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My 8 mile RT commute is a max of 35mph. My health club is a 15 mile RT with a max of 45mph. Those are my most common trips (I do most of my shopping as part of those trips as well). The key it seems is to NOT use the regenerative braking - I look ahead and coast a lot to stop lights, stop signs whenever possible. The less you have to do any braking, the better your range will be. I could probably get 130+ with low rolling resistance tires like I have on my 2000 Honda Insight.
The underlined text is exactly right, though counter-intuitive at first. When I first got my LEAF, I'd drive around using regen all the time, figuring I was getting good efficiency and confused as to why I wasn't. In retrospect, it was obvious where that was wrong (and a little embarrassing to me as an engineer).

Most anytime you convert energy from one form to another, there's a small loss. In our cars, every time we take energy out of the battery, we lose some (as heat). When we put that energy into the motor, we lose some (as heat). Every time we put energy back into the battery, we also lose some (again, as heat). Every moment we spend hurtling down the highway, we are losing energy (to air drag [heat]) and to rolling resistance in the tires [also heat]). We can't really avoid all forms of loss and still get utility out of the car, but we can minimize the number of times we take energy (kWh) out of the battery, turn it into kinetic energy, oops realize we're going faster than we want (having incurred higher air resistance along the way), take some of that kinetic energy away using the motor to turn that energy back into electricity (heat) and put that electricity back into the battery (heat) for use later.

It's obvious that using regen to slow down is better than using friction brakes (100% heat), but what's less obvious is that even better would have been to not have taken that excess energy out of the battery, turned it into motion, turned that motion back into electricity, and stored it again. Don't crash your car focusing too much on hyper-miling (that tosses out all the economy of several lifetimes of hyper-miling), and try not to be a rolling roadblock, but do be smooth, coast when you can, don't accelerate up to a stop sign, coast towards turn lanes, etc. Anytime you are regenerating, you are losing efficiency in the moment, you're just losing less than if you had to use friction brakes. (You're also learning that you used too much energy some moments prior when you used the "gas" instead of coasting.)

PS: (I'm sure DealMeIn and most forum members know this, but perhaps some haven't considered it: ) The Smart doesn't have a transmission (physically) that changes modes based on the "gear selector". Selecting "N" and back does no physical damage to the car.
 

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True, I have found my regen paddle option to be of greatest benefit when in the - (minus or freewheeling) mode especially on higher speed runs!

NOT for the faint of heart though if you forget that regen is off as you coast to a stop!
 

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The Smart doesn't have a transmission (physically) that changes modes based on the "gear selector". Selecting "N" and back does no physical damage to the car.
For reasons that are not explained, Smart specifically recommends against any extensive coasting in "neutral". Recall that that is why the smart is not supposed to be towed with the rear wheels on the ground. So, for non-paddle equipped Smarts (i.e. most Smarts) coasting is best done by feathering the throttle pedal so the needle power stays right at zero.

And I suspect that much of this advice regarding usage of regen is more applicable to flat area than hilly areas. Surely, it far more efficient to control speed down a hill using regen than service-braking.
 

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For reasons that are not explained, Smart specifically recommends against any extensive coasting in "neutral". Recall that that is why the smart is not supposed to be towed with the rear wheels on the ground. So, for non-paddle equipped Smarts (i.e. most Smarts) coasting is best done by feathering the throttle pedal so the needle power stays right at zero.
Interesting. I'll poke around @sokoloff's Smarts over Thanksgiving and have a think about why they might recommend that.

And I suspect that much of this advice regarding usage of regen is more applicable to flat area than hilly areas. Surely, it far more efficient to control speed down a hill using regen than service-braking.
Of course! Friction brakes << regen << coasting.
 
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