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Has anyone measured the kilowatt-hours consumed versus the miles driven for the 110 volt charging system and compared it to the 240 volt charging system. I have seen posts that 240 volt charging is more efficient (more miles per kilowatt-hour consumed). Would like to see some actual measurements on the same vehicle as this depends on a number of driving factors. I am currently measuring my Spark on the 110 volt charger with a cummulative watt meter and getting about 3.6 miles per kWHr (get 4.5 reported by the car but that does not take into account the inefficiencies of charging and discharging the battery) but I do not currently have a meter that works at 240 volts.
 

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I believe the spark has the same charging hardware that the Volt does, so the differences between 120 and 240 volt charging should be the same. I think the better efficiency is due to less battery and inverter cooling required for the 240 charging, since it takes about half the time.

The 4.5 miles per kWH vs 3.6 is due to the charging losses. For every 100 kwh you put into a battery, you get about 80 kwh back.

I get quite a bit lower miles per kwh, because I'm having too much fun driving it like I stole it. ;)
 

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Actually the energy loss in the charger, cables, and connections is more than what is lost in the battery.

240 V charging should be more efficient, since the loss is the same for a given current, but 240 V will provide twice the energy as 120 V for the current.

GSP
 

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I've just started measuring my Spark EV charging on a 110-V charge using a Kill-A-Watt meter. For the last charge, the car said it used 7.2 kWhrs but it took 9.7 kWhrs to charge it as measured at the wall plug via the Kill-A-Watt. So that's roughly in line with the 3.6 vs. 4.5 miles per kWhr. I'm planning to get a 240-V charging station eventually. I'll report further numbers as I collect them.
 

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AFAIK the Spark uses the same onboard charging unit as the Volt. The charger has a fixed loss around 315 watts regardless of the charging rate. This is the difference between the AC watts going in and the DC watts coming out. Obviously the longer the charging session, the more "wasted" power. 4 hours = 1.26 kWh overhead, 9 hours = 2.84 kWh overhead.
 

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I've done two charges now (for ~8 - 10 hours each)--one at 8 A and one at 12 A. Both were ~74% efficient as calculated by <What car says it used> divided by <what Kill-A-Watt says it took to charge the car>. That means that for the 8 A charging case, the charger had about 240 W of overhead, but for the 12 A case, 360 W. In either case it works out to the same total excess kWh (constant charging efficiency at 110 VAC). I am using a 50-ft extension cord, though, which is warm to the touch for the 12 A case, so I'll try removing that from the equation next. As it stands, I'm averaging 3.2 mi/kWh from the wall plug over these two days (60 miles of driving).

Update, 31-May-2014: I've now been monitoring the charging for about 500 miles. I'm averaging around 77% charging efficiency (long extension cord removed), and right around 3.1 miles per wall-plug kWh (all 110 VAC charging) when I don't use the A/C (~4.0 miles per kWh according to the car).

Edit: Thinking about it more, I would expect the 12 A charging to be less efficient since resistive losses will go as the square of the current (certainly in the charging cables), but apparently these are a small enough part of the charging efficiency that it was lost in my daily measurement variation.
 

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Interestingly, if you login to your my.chevrolet.com/web/portal account, you can view your Spark EV charging and mileage history for the last 30 days, day by day (or the last 12 months, month by month). The site has been flaky lately, but when it's up, click on "Charging and Efficiency," and then "Charts and Graphs." The numbers match pretty well what I've been logging every day, but they clearly list the wall-plug power used, not the kWh the Spark tells you it has consumed on its dashboard display (which is a lower number since it doesn't account for the charging efficiency). So the car knows and stores both. It's strange that the web site reports the one number, but the car's display reports the other number. The nice aspect of this is that I should be able to calculate the charging efficiency with 220 VAC charging (which I now have) and compare it to what I got with the 110 VAC charging (about 77%). Unfortunately, the web site numbers are all rounded to the nearest integer. Not sure why Chevy couldn't cough up one more decimal place, but it will take several days before I get some reasonable accuracy on the numbers because of that.
 

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...they clearly list the wall-plug power used, not the kWh the Spark tells you it has consumed on its dashboard display (which is a lower number since it doesn't account for the charging efficiency). So the car knows and stores both. It's strange that the web site reports the one number, but the car's display reports the other number. The nice aspect of this is that I should be able to calculate the charging efficiency with 220 VAC charging (which I now have) and compare it to what I got with the 110 VAC charging (about 77%). Unfortunately, the web site numbers are all rounded to the nearest integer. Not sure why Chevy couldn't cough up one more decimal place, but it will take several days before I get some reasonable accuracy on the numbers because of that.
I don't know this for a fact, but I will bet they simply apply a conversion factor to switch between wall plug power and kwh stored in the battery.
One thing I really wish the car's display would show is the miles, kwh used and miles per kwh since last full charge. They only show those numbers for the last driving session, which for me are always short trips throughout the day.

Btw: It is actually 120 and 240 volts, not 110 and 220.
 

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I don't know this for a fact, but I will bet they simply apply a conversion factor to switch between wall plug power and kwh stored in the battery.
One thing I really wish the car's display would show is the miles, kwh used and miles per kwh since last full charge. They only show those numbers for the last driving session, which for me are always short trips throughout the day...
If they just apply a factor, then it's a different one for 240 VAC vs. 120 VAC, because the charging efficiency based on the web site numbers increased when I switched from 120 VAC to 240 VAC. After about a week of charging at 240 VAC, it has increased from 81% to 89%. I'll have to see if it ends up jiving with my electric bill.

The car will at least tell you the kwh since last full charge--it's in the charging menu (or press the leaf button). But as far as I know you have to track the mileage yourself. The web portal also tracks mileage by day, but it doesn't quite match up with my daily log that I keep--I haven't figured that one out--maybe it's using GMT instead of my local time zone to break up the days? But the total for a stretch of several days matches what I have.
 

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After about 1000 miles of charging my 2014 Spark at 240 VAC using an AeroVironment Turbocord, my charging efficiency is right at 83%, up from 77.5% when I charged using 120 VAC (using the cord that came with the car). The Turbocord is AWG 14 and so consumes about 30 W at 16 A, thus reducing the efficiency by about 1 point over a perfectly conducting cord. I was able to get the 240 VAC kWh numbers because I charge only at night and can download my electric consumption from my electric company in the form of a spreadsheet which has it broken out by hour (I have a fancy new digital meter that they installed a couple years back). The background usage from my other appliances at night is very low and repeatable and can be subtracted out from what the cars consumes, giving me pretty accurate numbers. In general, I haven't used a lot of AC this summer. That does seem to lower the charging efficiency a bit--maybe because the 12 V battery also has to be re-charged? Don't know. The charging efficiency as calculated by the numbers from https://my.chevrolet.com/web/portal/ is 86%--three points higher than the numbers based on my electric company readings.

One thing I've noticed with the mileage--it definitely pays to break and accelerate gently. On days when I really make an effort to do that, I tend to get 4.5 - 4.9 miles/kWh as reported by the car (3.6 - 4.0 miles/kWh when factoring in the charging efficiency). When I drive more aggressively, the mileage tends to be ~0.5-1.0 miles/kWh lower.
 

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After 1700 miles n the Spark EV, onboard efficiency is at 5.5mpkWh (18 kWh/100miles) vs 25kWh/100 reported by ONStar. So that makes my charging loss 7kWh//25 ~ 28%. Charging almost exclusively at night with the stock EVSE from Chevy. I'm looking into getting L II for efficiency sake, even though I don't need the faster charge.
I am also going to try to stop 'topping off'. I haven't done much pre cooling' as the EV in the shade has been pretty cool to start.
 
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