EVsBasic Concepts, part 2

EV-102b

This course is presented as part of Evannex Universitya free, open learning environment that presents concise, video-based mini-courses for those who have interest in electric vehicles (EVs)

Electric Vehicles (EVs)

Electric Vehicles (EVs)

This presentation is a part 2 of our EVU mini-course discussion of basic concepts.If you havent already done so, please take a look at Part 1 before you proceed with this mini-course.

We left off with a preliminary discussion volts and amps and their real world relationship to your EV. There are lots of additional things we could discuss, but the bottom line is how volt and amps play a role in charging your vehicle.

And the best place to start is in your garage.

Volts and amps in your garageBegin at your service panelFlow through wires to your EVHigher the voltage, the more amps can be deliveredThe more amps delivered, the faster your battery charges

For the purposes of our discussion here , volts and amps live in your garage.

>> An electrician runs a line from your service panelthats the grey box on the wall in your basement or garage where your circuit breakers are located.He then runs a circuitelectrical wiringto the location where the charging outlet for your EV will be located, usually in your garage.

>> Electricity can then flow to that location.

Well talk a lot more about why volts and amps matter as you set up your garage charging circuit in more advanced EVU mini-courses, so we wont go into details here.

>> Suffice it to say that the higher the voltage, the more amps can be delivered to charge your battery.

>> And thats important, because the more amps delivered, the faster your battery charges.

Kilowatts (kW) and Kilowatt-Hours (kWh)A kilowatt (1000 watts) is a measure of power. But its also a measure of how quickly you fill your battery. A kilowatt-hour (kWh) is a measure of capacityhow big the bucket is.

Whenever EVs are discussed, youll likely hear people taking about kilowatts and kilowatt hours.

>> A kilowatt (1000 watts) is a measure of power. But its also a measure of how quickly you fill your battery.

>> A kilowatt-hour (kWh) is a measure of capacityhow big the bucket is or discarding the metaphor, how big your battery is.

Battery CapacitySmall EVs24kWhLarge EVs85kWhLarger results inBetter rangeBetter performance

So when you see an EV manufacturer that>> touts a 24kWh battery, and >> another that talks about an 85kWh battery understand that the former has much less capacity than the latter,

>> And as a consequence, >> the range of the first EV will be considerably less than the range of the second.

>> In addition, the larger battery also leads to better overall performanceacceleration and top speed.

ComparisonsMPGeMiles per gallon equivalent (MPGe)indicates the number of miles an EV can travel using electricity that delivers the same energy content as a gallon of gasolineallows mpg comparisonse.g., the Tesla Model S EV gets 95 MPGe

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But the bottom line is understanding how much youll save by driving an EV.

Right now in the united states, gas prices are relatively low, but even today, filling an EV costs about 20 percent of what it costs to fill a conventional car.

And if gas prices rise to, say, $4.00 a gallonwhere they were for much of 2013, an EV looks even better in real dollar terms.

With that in mind, two measures of consumption need to be consideredthe first is: miles per gallon-equivalent

>> Miles per gallon equivalent (MPGe)indicates the number of miles an EV can travel using electricity that delivers the same energy content as a gallon of gasoline

>> that allows mpg comparisons with ICE vehicles>> for example, the Tesla Model S EV gets 95 MPGe, 3 to 4 times better than comparable ICE vehicles

Comparisons among Vehicles

ElectricVehicles Plug-inHybridsHybridsICEVehiclesBest1241175042Average95924228Worst63882812

Source: www.fueleconomy.gov

It a bit difficult to do

Comparisons among Vehicles

ElectricVehicles Plug-inHybridsHybridsICEVehiclesBest1241175042Average95924228Worst63882812

Source: www.fueleconomy.gov

It a bit difficult to do direct comparisons between the four different vehicle architectures on the road today, but weve made an attempt, and provided a chart based on US DoE statistics at the website fuelconomy.gov

The best fuel economy in any vehicle category is always found in smaller, lighter vehicles, and the worst is typically associated with large heavier vehicles, like SUVs.

The MPGe values attributed to hybrid and plug-in hybrid vehicles depend dramatically on the typical distance that such vehicles travel on a regular basis.

If plug-in hybrids travel short distances only, they are comparable to EVs. However, if they travel longer distances regularly, say a 100 mile daily commute, their MPGe moves much closed to that of a fuel efficient ICE vehicle.

The very best EVs can get about 124 MPGe, and the very best ICE vehicles get around 42 mpg. Thats a 3 to 1 ratio in favor of EVs!

kWh per MileKilowatt hours per mile (kWh/mile)is a measure of energy consumption, but also,A measure of the efficiency of an EVTypically, EVs consume between 0.35 to 0.50 kWh/mileThe higher the speed the greater kWh consumptionSource: http://blog.maxdunn.com/articles/2009/03/19/tesla-efficiency

For EVs, there is another measure of consumption kWh per mile.

>> Kilowatt hours per mile (kWh/mile)is a measure of energy consumption, but also,>> A measure of the efficiency of an EV>> Typically, EVs consume between 0.30 to 0.50 kWh/mile

>> The higher the speed the greater kWh consumption

The graph on the right side of your screen illustrates this for the Tesla Model S. The vertical axis is kWh per mile consumed and the horizontal axis is mph.

It should come as no surprise that the faster your drive, the more energy you consume.

Well look at the reasons why in another EVU mini-course.

e-Gallon (DoE)The price of an e-Gallon tells consumers how much it costs to drive an EV the same distance you could go on a gallon of gas E-gallon ($/gal) = FE x EC x EPWhere FE = average fuel economy of a comparable ICE vehicle EC = average kWh/mile of the top five EVs EP = average price of a kWh of electricityAn online calculator can be found at: http://energy.gov/articles/egallon-and-electric-vehicle-sales-big-picture

Another consumption metric is the e-Gallon developed by the US DoE. They define it in the following manner: >> The price of an eGallon tells consumers how much it costs to drive an EV the same distance you could go on a gallon of unleaded gasoline in a similar car.

If youre interested in the technical details, heres a quick summary of the e-Gallon calculation.

>> E-gallon ($/gal) = FE x EC x EP

>>Where

>> FE = average fuel economy of a comparable ICE vehicle >> EC = average kWh/mile of the top five EVs >> EP = average price of a kWh of electricity

>> An online calculator can be found at the link shown on your screen.

SummaryVolts and amps live in your garage kWh is a measure of the capacity of an EV batteryMPGe, kWh per mile, and e-Gallon are all metrics that can be used to measure energy consumption

In this continuation of our Basic Concepts mini-course, we expanded on some basic terms that are encountered repeatedly in discussions of EVs.

>> Volts and amps live in your garage and have a significant impact of the way you can charge your EV

>> kWh is a measure of the capacity of an EV battery

>> MPGe, kWh per mile, and e-Gallon are all metrics that can be used to measure energy consumption and the relative efficiency of EVs

In the next EVU mini-course in this sequence, we move on to EV architectures. That will help you to understand how EVs actually work, and what options are available for those who want to enter the EV world.

a free study guide for all EVU mini-courses is available for download from our website For a complete list of mini-courses and the study guide, visit: www.evannex.com

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