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Discussion Starter #1
I've been trying to find a figure for the charging efficiency of the volt (i.e. how may KW per KVA). I've done a back of the envelope calculation as to the break even price for gas vs electric and it appears to be $3/gallon in Massachusetts where electricity is 21 cents/KW (assuming 100% efficiency which is impossible).
 

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It varies within a small window, depending on level 1 vs. level 2, and apparently full charge vs. partial, too, but as a rule of thumb, I've been using 85%.

--Chris
 

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I am not paying for my electricity, so I am always saving over the use of gasoline. Fuel costs me between $4 and $8 per month. From my observations at the charger, I am traveling on 6 KwH and losing 1 KwH at the charging station. That means that about 16% electricity loss in recharging at Level 2.
 

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The answer from GM is given in their SAE paper from last year.

http://papers.sae.org/2015-01-1152/

You can preview the first 5 pages, which will show the charger efficiency for Gen 2 as 94.5% on Level 1 and 95.5% on Level 2. However, this does not account for battery efficiency, coolant pump losses, etc.

On the next page of this paper, the Charging System efficiency is given as 86.7% on Level 1 and 88.4% on Level 2 (vs. 79.3% and 81.4% respectively for Gen 1).

I believe these results can be different for various ambient conditions.

My electric rates are about 14.5 cents per kWh (thanks to a competitive energy supplier). Lately I haven't used any heat or AC in my 2016 Volt, and my calculated MPGe is about 145 mpg. With these numbers, I am just under 3 cents per mile.

Even at 50 mpg for gasoline, this is less than $1.50 per gallon equivalent. So I have no issues with the efficiency of the 2016 Volt.
 

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I measure between 89.7% and 90.5%, overall, energy into the car versus energy out of the battery, all ancillary charging systems functioning normally, assuming the 10.5kWh to depleted battery is correct (as indicated on the screen, and as indicated in the battery specs).

I don't think it would be unreasonable to therefore assume 95% efficient delivery into the battery, and then 95% charging losses round trip in the battery.
 

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Discussion Starter #7
The answer from GM is given in their SAE paper from last year.

http://papers.sae.org/2015-01-1152/

You can preview the first 5 pages, which will show the charger efficiency for Gen 2 as 94.5% on Level 1 and 95.5% on Level 2. However, this does not account for battery efficiency, coolant pump losses, etc.

On the next page of this paper, the Charging System efficiency is given as 86.7% on Level 1 and 88.4% on Level 2 (vs. 79.3% and 81.4% respectively for Gen 1).

I believe these results can be different for various ambient conditions.

My electric rates are about 14.5 cents per kWh (thanks to a competitive energy supplier). Lately I haven't used any heat or AC in my 2016 Volt, and my calculated MPGe is about 145 mpg. With these numbers, I am just under 3 cents per mile.

Even at 50 mpg for gasoline, this is less than $1.50 per gallon equivalent. So I have no issues with the efficiency of the 2016 Volt.
There are two pieces of the electric bill, a generation charge and a distribution charge. I'm paying 11cents/KW as my generation charge from a competitive supplier but the total bill works out to about 21cents/KW which is typical for Massachusetts. Where do you live that you are paying only 14.5 cents?
 

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I measure between 89.7% and 90.5%, overall, energy into the car versus energy out of the battery, all ancillary charging systems functioning normally, assuming the 10.5kWh to depleted battery is correct (as indicated on the screen, and as indicated in the battery specs).

I don't think it would be unreasonable to therefore assume 95% efficient delivery into the battery, and then 95% charging losses round trip in the battery.
I second the ~90% figure while using 240V, based on my measurements.

However, this is only if not using any temperature conditioning (heating in winter, cooling in summer). I suspect the study numbers above took that into account.
 

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I second the ~90% figure while using 240V, based on my measurements.

However, this is only if not using any temperature conditioning (heating in winter, cooling in summer). I suspect the study numbers above took that into account.
Agreed. This is without battery heating or cooling. Whether it would be 'fair' to include that I wouldn't say, because it's not really a measure of charging efficiency but becomes one of 'operating' efficiency.
 

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There are two pieces of the electric bill, a generation charge and a distribution charge. I'm paying 11cents/KW as my generation charge from a competitive supplier but the total bill works out to about 21cents/KW which is typical for Massachusetts. Where do you live that you are paying only 14.5 cents?
It doesn't seem reasonable to me, that the distribution charge be included in your vehicle propulsion costs, as you would still accrue that cost even if you didn't have the Volt.
 

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There are two pieces of the electric bill, a generation charge and a distribution charge. I'm paying 11cents/KW as my generation charge from a competitive supplier but the total bill works out to about 21cents/KW which is typical for Massachusetts. Where do you live that you are paying only 14.5 cents?
I'm in NH and have Eversource for my utility (formerly PSNH in NH, but owned by the former Northeast Utilities). My delivery (transmission and distribution) charges are about 8 cents. I recently went with Direct Energy for the energy supply, and they provide energy for 6.57 cents until November (6 month term).

Let me know if you want to (or allowed to in MA) change to Direct Energy. They also offer a $50 gift card to me for providing the reference and for you as the referred party!
 

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It doesn't seem reasonable to me, that the distribution charge be included in your vehicle propulsion costs, as you would still accrue that cost even if you didn't have the Volt.
If the distribution charge is a rate per kWh, then of course it needs to be factored in as part of the energy costs for your Volt.

You may be thinking of the "customer charge", which is a flat fee per month. I exclude that from my propulsion costs, since I would pay exactly the same amount per month with or without charging my car.

--Chris
 

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I don't have a Volt but why worry about the charge efficiency? All electrical devices lose energy as heat due to resistance in the conductors and other materials. I bet if you have electrical appliances, they have worse energy efficiency than the Volt. Even a small appliance as a electric toaster loses over 50% of its energy into the air when it toasts the bread.

BTW, the best gasoline efficiency is less than 37% as most is lost as pure heat and sound (exhaust). So don't worry about charger efficiency as it is still better than any gas engine conversion. This is the main reason charging your Volt battery is much better than running the range extender.
 

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I don't have a Volt but why worry about the charge efficiency?
If you're in the process of trying to decide whether to buy an EV or not then the savings you can realize by paying less for electricity than for gas are a part of the decision process. And you need to know the charging efficiency to get the most accurate estimate of your electricity costs because you're billed based on how much juice goes out of the wall socket, not how much goes into the battery.

Even if you already own an electric car you may want to know how much you're paying to power it and the same rationale applies.
 

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I've been trying to find a figure for the charging efficiency of the volt (i.e. how may KW per KVA). I've done a back of the envelope calculation as to the break even price for gas vs electric and it appears to be $3/gallon in Massachusetts where electricity is 21 cents/KW (assuming 100% efficiency which is impossible).
Breakevens need 4 pieces of data. You have two, the price per gallon and the price per kWh. You also need your driving efficiency under gas and electric. When I punch in your prices into my efficiency levels, I don't get breakeven. If you use typical efficiencies of say, 4miles/kWh and 40mpg, you'd get 5.25 cents/mile for electric and 7.5 cents/mile for gas.
 

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Discussion Starter #16
The distribution charge is per KW it's not a flat rate so it has to be included in the cost per KW.
 

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The distribution charge is per KW it's not a flat rate so it has to be included in the cost per KW.
(You mean per kWh, presumably?)

Just as a matter of interest... is the logic behind a per kWh distribution charge because drawing more electrons wears the wires out quicker?
 

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Discussion Starter #18
The logic behind it is that the lawyers for the utilities were able to convince the regulators to allow it. I have my bill in front of me, it adds up to 21.4cents/KW. There is a fixed $4 customer charge, everything else is per KWH, here are the items
Dist Chg First 600 KWH 0.04172376
Dist Chg Next 993 KWH 0.04834376
Transition Charge -0.00035
Transmission Charge 0.02829
Energy Efficiency Charge 0.01734343
Renewable Energy Charge 0.0005

Then the part which comes from a different supplier
Electricity Supply 0.1199

My total bill is $340.98 for 1593 KWH which comes out to 21.04 cents/KWH
 

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The logic behind it is that the lawyers for the utilities were able to convince the regulators to allow it. I have my bill in front of me, it adds up to 21.4cents/KW. There is a fixed $4 customer charge, everything else is per KWH, here are the items
Dist Chg First 600 KWH 0.04172376
Dist Chg Next 993 KWH 0.04834376
Transition Charge -0.00035
Transmission Charge 0.02829
Energy Efficiency Charge 0.01734343
Renewable Energy Charge 0.0005

Then the part which comes from a different supplier
Electricity Supply 0.1199

My total bill is $340.98 for 1593 KWH which comes out to 21.04 cents/KWH
If I understand your bill, the actual cost of the electricity is $0.1199/kWh, and the rest is overhead/infrastructure. The utilities are like the airlines, adding all types of charges to confuse the consumer and increasing their revenue. Our PGE gas/electric bill and telecom bills have so many additional charges, it is not clear what they all mean - another form of "nickeling and diming" us to add to their revenue.
 

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Discussion Starter #20
If I understand your bill, the actual cost of the electricity is $0.1199/kWh, and the rest is overhead/infrastructure. The utilities are like the airlines, adding all types of charges to confuse the consumer and increasing their revenue. Our PGE gas/electric bill and telecom bills have so many additional charges, it is not clear what they all mean - another form of "nickeling and diming" us to add to their revenue.
The bottom line is that the competitive part of the bill, the supply charge, accounts for about half of the total charge but what really counts is the total charge which in my case (in Massachusetts) is 21.4 cents/KWH. Adjusting for a 90% charging efficiency that works out to 23.8 per KVA. The Volt has an 18.4KVA battery which will take you 53 miles at a cost of $4.38 (8.26 cents per mile). The gas engine in the Volt is 42MPG so the equivalent price per gallon is $3.46, the current price of gasoline in Massachusetts is about $2.31 for regular or $2.51 for mid grade.
 
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