01.31.2011 - by Tom Saxton
Understanding Electric Vehicle Charging

Trading a gas pump for a plug is a wonderful thing. It’s far more convenient, takes less of your time, and saves you from breathing toxic fumes and smelling like gas for hours after fueling. Charging is a different experience than pumping gas and understanding the subtleties takes time. I’ve been driving electric for over two years and I’m still learning. Potential EV owners might want to get a head start on the learning curve, and maybe save a bunch of money as a result.

Mostly, I’ll relate how charging works for a Nissan Leaf, a four-door, five-passenger hatchback with a range of about 100 miles, but I’ll also mention other plug-in vehicles. The Leaf is intended for typical daily driving, which for 78% of drivers in the US means 40 miles or less per day. Occasional longer trips are possible and understanding charging will help you evaluate whether an EV will suit your driving needs.

Level 1 Charging

Level 1 Charging - Standard house outlet

Level 1 Charging – Standard House Outlet

Level 1 charging is the technical jargon for plugging your car into an ordinary household outlet. For a Leaf, this means about 4.5 miles of range per hour of charging, or about 22 hours for a full charge. Wow, does that sound terrible! But there’s a problem with thinking this way: you’ll rarely need to do a full charge from flat empty to full. If you drive 40 miles per day and charge overnight, you’ll be back to full in 9 hours. When you’re sleeping, it doesn’t matter if it takes one hour or 9 hours to charge.

But what if you have to drive a lot one day, say 80 miles? Sure, it would take 18 hours to get a full charge, but with a 9-hour overnight charge, you’ll be ready for your normal commute the next day. If you drive less than 40 miles per day or charge for more than 9 hours, you’ll work back up to a full charge over the next few days.

If you need to drive 80 miles on consecutive days, you’ll need an alternative. Maybe you’ll drive your other car, that gas-burner you keep around for long trips, or if there’s public EV charging in your area, you can charge away from home while you’re parked to do your shopping or other errands.

Level 1 charging at work could also be a supplement for people driving over 40 miles per day, or even a substitute for those who can’t charge at home (because they don’t have a garage or fixed parking place, for example).

Since it’s easy to get 40 miles of range charging overnight from 120V, Level 1 is perfectly suited for overnight charging of the Chevy Volt, a plug-in hybrid with a 40-mile all-electric range.

Although Level 1 charging is generally too slow for a road trip, it can be helpful as destination charging. Cathy and I drove 90 miles to San Juan Island, charged for a few days in a friend’s garage when not cruising around the island, and left with a full charge. That was great, but I wouldn’t want to have to wait for Level 1 charging in the middle of a travel segment.

Beyond range issues, Level 1 may not be suitable for primary charging in all cases. In extreme climates, more power may be required to maintain proper battery temperatures. In these cases, Level 2 charging may be more appropriate (see below).

DC Fast Charging

The Blink DC Fast Charge Station

Blink DC Fast Charge Station photo by ECOtality

At the other end of the spectrum is DC Fast Charging, the fastest type of charging currently available. It provides up to 40 miles of range for every 10 minutes of charging. These stations are expensive (up to $100,000) and require more power than your house, so you’ll never have one of these in your garage.

They are going to start appearing as public charging stations in the next year, beginning in the Leaf target areas. If there’s one conveniently located near where you drive, you can get back up to 80% of a full charge while getting lunch or drinking a latte. Charging this fast makes it far more practical to drive beyond an EV’s single-charge range in one day. It’s still not going to make a one-day 800-mile drive practical, but a 200-mile drive with a couple of charging breaks can be quite doable.

Level 2 Charging

ChargePoint/Coulomb Level 2 Charging Station

ChargePoint/Coulomb Level 2 Charging Station

Between the cheap Level 1 and expensive DC Fast Charging stations sits Level 2 charging. Level 2 supplies 240V, like what an electric dryer or oven uses. It goes through a box and a cord that improves safety by waiting to send power to the plug until it’s plugged into an EV. Level 2 allows for a wide range of charging speeds, all the way up to 19.2 kilowatts (kW), or about 70 miles of range per hour of charging.

However, the charging stations being put in with federal grant money don’t support the full range of Level 2 charging and max out at 6.6 kW or around 26 miles of range per hour of charging.

Both Level 1 and Level 2 charging stations simply deliver household electricity to the car. Electronics on board the car transform the wall power into the proper form to charge the battery. This bit of electronics built into the car also has a maximum power rating. The first model-year Leafs can only use 3.3 kW, about 12 miles of range per hour, or about 8 hours for a full charge from empty. The Chevy Volt’s on-board charger is also limited to 3.3 kW, although its smaller battery pack gets full sooner.

Nissan recommends that you install a Level 2 charging station at home. That’s a reasonable thing to do if you don’t mind spending about $2,000, just consider it part of the cost of the car. Early buyers in the Leaf target markets may be able to get into The EV Project and get a free Level 2 charging station plus an allowance toward the install cost. Failing that, there’s a 30% federal tax credit (up to $1,000) for installing EV charging, which can make it less expensive. Still, if you are planning to use your EV for a daily commute of 40 miles or less per day, you should at least consider using Level 1 charging at home. You can always add a Level 2 charging station later if you decide you need it.

There will soon be 20,000 public Level 2 charging stations (limited to 6.6 kW) installed mainly in the Leaf target areas. Even if you only have Level 1 charging in your garage, if you’re in the early rollout areas, you should have access to convenient Level 2 charging available while your car is parked and you’re doing something else. These charging stations will make it possible to drive 60 miles to a baseball game and pick up about 50 miles of range in 4 hours while you’re having fun, thus easily driving over the single-charge range while always keeping a healthy reserve.

Charge Time and Battery Capacity

It’s misleading that charging times are generally quoted as time for a full charge. While it does take about 22 hours (Level 1) or 8 hours (Level 2) to charge a Leaf from empty to full, you’re not likely to do that often because you will rarely arrive home with a fully depleted battery. It doesn’t matter if you’re driving a 40-mile Volt, a 100-mile Leaf or a 240-mile Tesla Roadster, if your commute is 40 miles, you’ll only need about 9 hours (Level 1) or 3 hours (3.3 kW Level 2) to charge.

When we bought our Tesla Roadster, we got the high-power 16.8 kW Level 2 charging station, which can charge the car in 3.5 hours. After driving the car for a few months, I realized it’s all but pointless to have such a big charging station in our garage. It’s rare that I drive over 40 miles in a day. The 16.8 kW charging station can restore 40 miles in under 40 minutes. I want that charging speed when I’m making a long trip, not when I’m sleeping at home. In fact, I manually drop the power I pull from the charging station to about 7.5 kW because it’s a little nicer to our electrical panel and the grid, and my typical overnight charge is still under 2 hours. Ignoring the fact that Tesla is still using the now-incompatible proprietary charging plug they picked before there was a chosen standard, most people buying a Tesla Roadster today would be well-served to buy a 6.6 kW charging station for home.

3 Roadsters Sharing the Charging Station at Burgerville

3 Roadsters Sharing the Charging Station at Burgerville

Level 2 Charging, Road Trips, and Charging Speed

Already, Ford has announced that the upcoming electric Ford Focus will support charging at 6.6 kW, and is making fun of the Leaf’s 3.3 kW Level 2 charging limit. By the time Ford actually starts delivering the electric Focus, Nissan may have already upgraded the Leaf to 6.6 kW charging. I don’t think it will be long before mainstream EVs are capable of even faster charging. The Tesla Roadster can charge at 16.8 kW, which combined with a larger battery pack makes 400-mile drives possible even without DC Fast Charging. Given that Level 2 charging costs 1/10 of what a DC Fast Charger does, I can imagine a lot of driving being supported by full Level 2 charging stations in areas that can’t justify the investment in DC Fast Charging.

Personally, I’m disappointed we’re spending so much money installing these 6.6 kW public charging stations rather than full-speed Level 2 chargers when most of the expense is usually just running the wires and buying the fancy box. A typical commercial Level 2 install runs around $10,000 for a charging station that’s connected to a network and capable of billing the user. Cranking those charging stations up to the 19.2 kW limit would add a small incremental cost, perhaps 10% to 20%, and would allow for much faster charging. If you’re a business owner installing a charging station and have to dig a trench and/or run conduit, even if it’s just a for 6.6 kW unit, I strongly recommend planning for running 100A wire later without having to retrench or replace conduit so that upgrading to a 19.2 kW charging station will be much less expensive.

60 comments on “Understanding Electric Vehicle Charging”
  1. Matt says:

    I had a technical question about ev charging. If my garage has a level 2 home charger (32A) but I get a vehicle that has an onboard charger that is only 3.3kw, can it still be plugged in to the higher level charger safely? Don’t expect faster chargong, just want to make sure I won’t fry something in the car.

  2. rabih says:

    a nissan leaf comes with 120 volt charge cable
    my electrical outlet is 220 volt
    can somone help explaining how the onboard charger will accept 220 volt ?

  3. talluri vaishnavi says:

    Suppose that an electric sport-utility passenger vehicle expends energy at a rate of 220Wh/km while driving. If this vehicle’s battery pack is charged at a 6.6kW rate, what is the rate of range added to the battery in “km (of range added to battery charge) per hour”? Round your answer to the nearest “km/h”

    can you answer

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  5. Naeem says:

    Suppose that an electric sport-utility passenger vehicle expends energy at a rate of 220Wh/km while driving. If this vehicle’s battery pack is charged at a 6.6kW rate, what is the rate of range added to the battery in “km (of range added to battery charge) per hour”?

  6. Mike says:

    Is there really such a think as a higher output level 1 charger? 110 v is 110 v but some Level 1 chargers say they can charge faster than stock level 1 chargers supplied with the car.

  7. Steve says:

    I just had a company here in the Olympia, WA area install one for me for my Telsa. The EV charging station that he put in my garage needed some extra work done to my electrical panel. They were a lot cheaper than everyone else. https://sparkselectricllc.com/olympia-electrician/

  8. Jamie says:

    Thank you so much for this post; Googling about gave me nothing useful until I landed upon your article. It may seem dated to some folks but I appreciate it today. My neighbor bought the iPace and needs me to explain the charging stations and how to use them. This has gone a long way to getting me there.

  9. Rhianna Hawk says:

    My husband and I want to get an electric car, and you’ve really helped us understand better what that would entail in terms of charging stations. It’s really nice to know that charging time is actually much shorter than is even listed on the quote, because like you said, you don’t come home with a dead battery. Unplugging at night after the car is charged is a good idea, too, for saving energy costs, and we’ll definitely remember that if we end up getting an EV.

  10. Randy says:

    I am contemplating buying an EV VW Golf my drive is 47 miles each way to and from work, I have a charging station at work, will it be harmful to the battery long term to charge the battery at night and then during the day? My drive is all interstate and I will be using the AC and or heater every day

  11. Lem says:

    Good informative article.
    I’m getting a used Spark EV and have a Clipper Creek in the carport. I’ve read freezing temperatures are not good for the battery and so you should have it plugged in. But I’ve also read not to overcharge your battery. Would you suggest getting a 120 volt outlet put outside or what?

  12. Devarajan k says:

    dear sir ,
    i have doubt how to fast dc charger work?with in 30 minutes how to fully charged?difference between dc slow charger and fast charger ?(like voltage and current).if fast charger 30 minutes fully charged why you they give slow charger option ?because every one like fast charger only..by fast charging any affect battery life time..

  13. Roben Pinson says:

    Well, I’m not sure amps are as important as volts for the level 2 application and charging times. I just purchased a 2015 Leaf with 35k miles. Charging at 110v level 1 takes every bit of 12-14 hours from >30% charge remaining. Installed a 240v outlet with a 10-30 weather rated clothes dryer type outlet and purchased a ZenCar level 2 16 amp charger with 10-30 connector. Leaf’s readout says 4 hours to full charge @240, and it takes exactly 4 hours. That’s because of Ohm’s Law. Increasing the voltage increases the flow of electricity. https://science.howstuffworks.com/environmental/energy/question501.htm
    It’s not hard to visualize when your brother the electrician is hooking it up to your new 20 amp breaker in your home’s breaker box, because 240v breaker has two hot leads as opposed to one for 110. So simple. For charging an EV, which is a high voltage device, voltage matters much more than amps. The ZenCar 16A 240v charger is $220. A fancy 40A wall charger from Clipper Creek or other is $600 or more and is simply not worth the cost IMHO. You will not get $400 worth of faster/better charging. Note that the Leaf’s owners manual did not recommend any amperage rating, just level 2, 240v. I also found a hole in the “charge to 80%” theory. TheLeaf’s owner’s manual states that the blue charging indicator lights on the dash indicate the levels of charge during charging, and that after the Li-Ion battery is fully charged, the #3 blue light will flash by itself to indicate that the 12 volt battery is being charged. Since the 12v battery runs the accessories, you may be risking your 12v battery by not fully charging. Follow your manufacturers instructions and speak with your qualified EV mechanic and an electrician. Overall conditions, weather, driving, traffic, speed and other factors can and do lead to varying charge and discharge results!

  14. Scott says:

    What is the miles per hour speed difference between a 16amp 240v EVSE and a 32amp EVSE? There is quite a difference in price between these EVSEs. Assuming my car accepts 6.6kw charging.

  15. Robin Stiles says:

    We have a 2018 Bolt and solar panels on our roof. When the sun shines we plug in the Bolt. I want to know how many kIlowatts the Bolt battery draws at any moment, or in an hour. I found a chart that shows the draw of a washer, a dishwasher, a coffeemaker, an iron, etc. but it did not list an EV!

  16. Gene Floyd says:

    Hi, looking at planning a road trip with a rental Soul EV out around the Cascades Loop (which looks very doable) and to Neah Bay, Graves Creek Campground and back which I’m not so sure about. Have you ever tried this? Would love some expert and local input on this.. I’ve found chargers in Gardiner (have already messaged the owner who happens to be a friend on FB to find out what type of charger / level etc) and Port Angeles, with others at Hobucks Beach, Sol Duc Lodge,, and Klalaloch Lodge but not completely sure how they are on charging times. The Soul I’m renting is stated to have an 80-mile range per charge

  17. vishalsharmaaa says:

    hello .realy charging times are generally quoted as time for a full charge. While it does take about 22 hours (Level 1) or 8 hours (Level 2) to charge a Leaf from empty to full, you will not likely to do that often .yes .I like .my Battery savety .

  18. Zilvia says:

    This is maybe a wild shot, but does anybody know how many DC fans would be needed per these 3 types of EV charging stations for thermal management? Thanks ahead!

  19. Matt says:

    I’m looking to know how many kWh’s it takes to go from empty to full on a Nissan Leaf 2018. My goal is attempting to get a better gauge of monthly usage of kWh’s as I’m also looking to potentially install a Solar System, and want to try to pull in the proper amount of energy from the sun 😉 We currently use 150-200 kwh to a max of 400kWh one month.

    More info… my commute is 50miles round trip, and the 2018 gets about 150 miles per full battery… rounding down and planning on averages being lower than dealer claims (especially in winter months) I’m figuring something like a full charge every 2 days full commute (~ 100 miles)

    so, figuring 5 days a week at 50 miles per day, (We get about 24 work days I a month), we’re at about 1,200 miles per month. So, I feel I’d need to “fully charge” ~ 10-12 times…

  20. Jeff says:

    Can anyone shed light on the price difference on your electric bill if you use level 1 vs. level 2? The charging time on level 2 seems to be less than half the time than the level 1 charging.

    1. Geoff says:

      It depends on your utility’s rate schedule. If you pay only for kWh, then there should be no difference between L1 and L2 since both are going to provide the same kWh, just over different time periods. That would be typical for a residential rate schedule. If you also pay a demand charge, as in a typical commercial rate schedule, then the higher kW L2 charging could increase that component of your bill, but only if it us used during your peak demand for the billing period.

    2. Jeff says:

      Jeff, negligible cost difference on you electric bill between Level 1 and Level 2 charging. Either way you will be consuming virtually the same number of kilowatt-hours. Level 2 is slightly more efficient, but not enough more that it would make a noticeable difference.

      1. Rockford Wells says:

        there is a difference in charging efficiency between level 1 and 2. It’s about 83% eff for level 2 and 75% for level 1. this means you would charge your battery with 8% less power on level 2. Don’t know where I picked this up. I am wondering if there is a difference in level 1 charging eff at 12 amps and 8 amps?

  21. Ken says:

    I have a question. This may not be practical in most cases, but why isn’t there a level 1 charging option that’s 24 amps, so you can get close to 9 mph range with only 120 volt outlet(s) available? What determines the 12 amp charging rate? is it the vehicle charging management system, or the car manufactures charger unit that comes with the 120 volt plug? If a person had two separate 120 volt circuits available off two separate circuit breakers, why isn’t there a multiple plug charger available to double the level 1 charge rate, or a two circuit joining plug so you could use two level 1 chargers simultaneously to reach a charge rate of 24 amps at 120 volts. Just curious. Also, I believe some 120 volt circuits are rated for up to 30 Amps – so why not a 24 amp charger available for these rare, but possible situations. Is the car charge circuitry set up for 12 amps only? Period?

    1. David says:

      Surprise, you can… Check out this link https://www.quick220.com/blog/go-farther-with-a-110-to-220-ev-charger/

      You will really be charging at 240 volts and more efficiently.

  22. Vihan Mapa says:

    Why do we need to install a home charging station instead of using Onboard charger. Quick response is highly appreciated.
    Many Thanks

  23. Keith says:

    I put a 240 volt outlet on the side of my house
    Bought a $175 dollar charger cable level 2
    Charge my smart fortwo at 5.2 KW all the time

    I made a relay box, controlled by wifi plug then scheduled.

    Works great for 7 months now

  24. Phil Cunliffe says:

    Hi Tom,

    I sometimes charge my BMW i3 in my condo garage and want to pay my neighbours for the power I use with the i3’s Level 1 charger. However, I have no way of measuring the number of kWh actually consumed, as is shown on Level 2 public charging points I’d settle for a close estimate based on the percent of a full charge, if this could be measured in kWh. Do you know how this might best be accomplished? Many thanks for your help and expertise.

    1. Howdy Phil. Plug In America’s Chief Science Officer, Tom Saxton answers your question below. Thanks for asking the EV Experts! – The Plug In America Team

      The most accurate method [to measure] is to use an electric meter, like the Kill-A-Watt. You can buy one for about $20. For example, here’s the Kill-A-Watt on Amazon:


      Note that if it loses power, it loses the reading, so you have to read it after each charge and record the value.

      Another method would be to calculate an approximate value by charge time. If you know how long you charged, multiply hours by 1.44 to get kWh. If a charge takes 3.5 hours, that’s about 2.5 x 1.44 = 3.6 kWh.

      You can get a rough estimate based on battery percent before and after the charge, but that method has two problems that make doing that problematic: there’s charging overhead that depends on environmental conditions (meaning it takes more than 20 kWh from the wall to add 20 kWh to a battery pack) and you have to know your pack’s useable capacity which changes with environmental conditions and age. Suppose your car has a usable pack capacity of 18.8 kWh and you charge from 40% to 100%. That means you added 60% of 18.8, or 0.60 x 18.8 = 11.28 kWh. Then add maybe 15% for charging overhead (the actual value could be higher or lower), so 1.15 x 11.28 = 12.97 kWh.

      – Tom

      1. Phil Cunliffe says:

        Many thanks for the speedy recommendation. I’ve already ordered an electric meter similar to the one you suggested and am confident it’ll fit the bill perfectly.

  25. Jake says:

    Rudimentary question here but when I charge my car at home with a level 2 outlet and the car (BMWi3) completes the charge, but I haven’t disconnected the charger, is it still pulling electricity from my home that I will be charged for? Thanks.

  26. Alfred says:

    In Manitoba, Canada,we have 5 to 6 months of winter with temperatures reaching -30 degrees Celsius, How do the lithium batteries react or hold their charge and for how long, I understand these vehicles would be good for city travel, but I would be skeptical over long distances, it is a long way across the prairies in Canada and in the U.S.A.

    1. Stephen C Shea says:

      Lithium batteries should ideally be charged at room temperaturev and not at low temperatures so make sure the car your are interested in h as a battery heat maintaiing circuit. Same goes for driving…lithium battery perform better at 70-90F and lose capacity when the battery temperature drops below that. Any vehicle you consider should have those issues engineered in. Steve

      1. Stephen C Shea says:

        Also no to all evs use li ion. The prep for example uses NiMH chemistry in it’s battery pack. Similar issues as apply to any battery chemistry however.

  27. OWL70 says:

    i would like to modify my level one on a Prius prime. is that possible

    1. Rockford Wells says:

      I have a 2018 Prius Prime and charging it tripped my breaker. Theoretically this should not happen as 12 amps is not enough to trip a breaker. I think there is something happening with the Prius charger (heat?) which causes an increase in the 12 amp max current.
      Solution is you can reduce the charge current to 8 amps by going to vehical settings then charge settings.

  28. Twila says:

    I would like information on adapting my Level 1 Leaf (2013) charger to A Level 2.
    I would really appreciate that information!
    Thank you!

  29. Anonymous says:

    I modified my level 1 charger that came with the Leaf and have used it as a Level 2 for nearly 2 years, Cost about $100 and works like a dream!! The idea of a $2000 level 2 charging outlet is crazy!!! If you want details email me directly at rdoctors at g****l.com

    1. Twila Giddings says:

      that would be awesome to have that information on how to alter the level 1 charger to a level 2 charger – I have a 2013 Leaf

    2. Brian says:

      I just bought a Chevy bolt, I would love to know how to modify the level 1 charger to a level 2

  30. Anonymous says:

    Can you comment on the following issue: I plug my EV into a public charging station and go off to do my business. The car is sitting there all day – how does this affect other users who drive up expecting to charge their vehicles? There’s a public charging station about 4 blocks from where I work – perfect as I wouldn’t mind parking there, plugging in, walking to work and then coming back at the end of the day. But I’m sure that wouldn’t be allowed?

  31. Dan Cohen says:

    Hi Tom:

    I live on Maui where we pay around .25/kW. I had an EV (ex airport) 25 years ago with lead-cell batteries.

    I’d like to get an EV again, and I wonder – would it be possible to charge Lead-cell batteries off a PV system, then charge an EV from the battery-bank? I believe I had 16 6V deepcycle batteries in that old Honda 600 van, which used to sell for about $50 ea/ probably double now. Seems like DC to DC should be a mucher faster charging time.

    Our local power company charges thousands just to evalutate hooking up a PV-metering system, and they do not pay for excess electricity produced beyond homeowner’s consumption.



    1. Dan Cohen says:

      *much faster*

    2. themotorman says:

      YOu can charge directly from the solar panels. You need to have enough panels to produce at least 2.5 volts x number of cells. e.g for your 16 x6 = 96 cells you’d need a system that puts out 2.5 x 96 volts = 240 volts. You then need someway to stop charging when the cells are charged as overcharging is bad for them. The simplest would be a controller ( Arizona windsun ) have them and are very helpful for off grid applications. For best battery life you need to have a cell balancing method and again they are available.

      1. F. R. Eggers says:

        An EV CANNOT be directly charged from PV panels if the EV will be used during the day. If the EV has to be charged from a PV system at night, then obviously the PV system must charge batteries independent of the EV then, at night, the EV would be charged from the batteries that the PV system had charged during the day. That does sound a bit inefficient and cumbersome.

        So, the answer you gave to the poster did not address his question.

    3. Anonymous says:

      SolarEdge has a grid connected Solar PV inverter for the solar PV system and it comes with a Level 2 charger. It is also HECO/HELCO/MECO friendly.

  32. Dave Mann says:

    All excellent information. Many thanks for the run down. I am in a target area (3 miles from Nissan HQ, actually). Question is, in the case of public charging stations, will credit/debit cards be required? After all, someone has to pay for the electricity being used to charge the vehicle. How are the charging stations collecting payment now that they are being installed?

    1. Tom says:

      Billing for charging is a very complex issue, worthy of a whole different article at least. Here are some quick thoughts for now…

      – Electricity is cheap, so cheap it’s often more expensive to pay for billing infrastructure than it is to give the electricity away.

      – The cost of electricity given away is an investment in our future independence from oil and represents a public good.

      – Sites that install charging to encourage EV use would often rather have free charging stations that get used to raise awareness about EVs than paid stations that don’t.

      – Businesses often want to attract customers and the minor cost of a little electricity is more than made up for in increased business.

      – For stations that do bill for charging, there are many options such as charge network membership cards, direct credit card support, or premium parking rates for spots that offer charging.

      We’re in a delicate phase now where charging infrastructure is being installed to promote electric vehicle ownership, which in turn will create demand for charging. As ownership increases to the point where infrastructure needs to be reserved for those who really need to charge, we’ll likely see a shift in billing practices. At the same time, businesses may find it necessary to offer free or inexpensive charging to attract customers from a wider geographical area.

      1. Michael says:

        Tom, I think that if you examine your own home utility bill you’ll find that electricity is not so cheap. The often quoted $0.11/KWHR as the national average cost for electricity doesn’t represent the full cost of “delivered” power, which includes transportation and distribution charges, plus the multitude of fees charged by the utility companies. Also, as your consumption over your baseline goes up, so does the rate charged. My guess is that the average person pays around $0.20/KWHR for delivered power, and if they buy and start charging an electric car at home, that rate will go up considerably with their increase in daily consumption. Even at a flat $0.20/KWHR, charging your Leaf with a half-charge per day, 12 KWHRs, for a month works out to $72 added electrical cost on your electric bill. The notion of “giving away” power is not a sustainable one–subsidizing private transportation costs with taxpayer-provided electricity in the case of public charging stations, or company-provided electricity in the case of private charging stations, does not encourage energy conservation, charger time sharing, or the ethical concept of paying for what you use. In the case of taxpayers, they are already subsidizing the cost of the electric car and the cost of the public charging infrastructure, should they really pay for the electric car owner’s fuel too? Owners of fossil fuel vehicles will not be too keen about subsidies for electric cars when they are paying for their own fuel, including the fuel taxes for maintaining the road infrastructure. Billing for charging does not have to be a complex issue: The bill needs to cover the cost of the electricity used in KWHRs, a fee to the owner of the charger for its cost and maintenance, a transaction fee for the services provided by the biller, and a fee to cover road use taxes that is based on mileage. When it’s all said and done, the real cost of charging your electric vehicle at your home and at public or corporate charging stations, will not be much cheaper than the cost of gasoline.

        1. Tom says:

          Michael, trust me, I’ve looked at our utility bill. Our top marginal rate is 10.3561 cents per kWh. We pay another 1.25 cents for green power and 1.3593 in taxes and fees, less 0.339 cents in credits, for a total of 12.6264 cents per kWh. Our base rate is a few cents cheaper than that.

          Under your scenario, putting 12 kWh into a LEAF every day for 30 days would mean driving 40 to 50 miles per day. Let’s take the low number and call it 1,200 miles per month. At our top electric rate, we’d pay $45 dollars in electricity. At $4 per gallon, that same 45 dollars would buy 11.3 gallons. So to get the same cost is a gas car, I’d need to get 106 MPG. Even at 20 cents per kWh, that’s equivalent to 62 miles per gallon.

          Taxpayer subsidies for oil far exceed those for electric cars. Since 1973, the US has spent about $90 billion per year to secure foreign oil fields and oil routes. That’s over $1 per gallon. That doesn’t count our oil-motivated wars in the middle east, tax breaks to oil companies, or the healthcare costs associated with burning oil and the urban air pollution it causes.

          Finally, I didn’t say electricity needs to be free. I said that business may make a better return by offering free charging to attract customers. We went on a vacation recently and had to choose between two B&Bs. They both said they would allow us to charge overnight, but one wanted to charge us $20 for $1.60 worth of electricity, the other said it would be free. The one that gave us free charging got our business and made much more than $1.60 on the deal. Businesses should do what makes sense, but it requires some thought to get it right.

          1. Anonymous says:

            Just want to thank everyone who contributes to this wonderful web site. I was trying to decide if I want my next car to be an EV, and now I am sure. (Also, I test drove the Nissan Leaf yesterday and loved it!) I am going to join your organization and do what I can to help get our country less and less dependent on fossil fuels. This will take decades, but I have faith that my young children will one day breathe cleaner air and have no idea how to fill up a gas tank.

          2. Rebecca Jandzinski says:

            I charged my Leaf at home with a level 2 charger that we installed through our electric panel for over a year. I saw no noticeable difference in our electric bill. I’m currently charging at two local businesses as I haven’t installed the charger at my new home. One is a Nissan dealership (DC fast), which charges a flat fee for a full charge. The other is a Kohl’s level 2, which is free (and takes 2 to 2 1/2 hours to fully charge). The time is the issue for me. Having a charger at home is definitely more convenient. I’m looking at purchasing a plug in charger as the GE charger I have requires an electrician to install it through wiring. Would you recommend a level 1, or should I purchase the level 2?

        2. Anonymous says:

          We have an especially economical EV, and PG&E has a special rate for EVs; four cents per KWH.
          But putting that all aside, and assuming the very high use of electricity per mile (we figure we use one KWH per five miles; more or less; less than five on the freeway at high speeds, more in town at or below 40 mph) that you quote, the difference in cost per mile for electricity versus gasoline is MUCH greater than you suggest! We figure we AVERAGE one cent per mile (quite a bit less, actually, when we measure it) in our EV, and about 10 to 15 cents per mile in our (very economical) gas-burner!
          So, get real – in addition to a huge savings in pollution, we get a very real, large savings in cost per mile (and our EV is maintenance-free – check the brakes after about 40,000 miles, the tires when they lose tread – that’s it!).

  33. Terrific article Tom. I really learned a lot. Since you’re willing to offer reasoned opinions, here is a question for you:
    In a 6-unit Santa Monica, CA apartment building with 2-40amp switches reserved for common area usage, would you recommend a level 1&2 charger be installed for potential/future EV-driving residents or just a level 2? Why?
    Keeping the future and the building location in mind, do you think one charger is enough?
    Thanks again for providing such wonderful information.

    1. Tom says:

      There are a number of issues with multi-family units: access to charging for EVs for owners, access for owners with wheelchair or other requirements, etc. Plug In America did an online conference about this very subject last week:


      Perhaps that will get posted online. It’s a hot topic and it’s all too easy to just plant a charger near a parking spot and end up with it not being usable.

      As for Level 1 and/or Level 2, I’d recommend a Level 2 charger. If there’s a proper outdoor outlet in the vicinity, I wouldn’t bother paying much extra to add Level 1 to a charging station. Unless you want to add charging right away to enhance the property value, I’d take a cautious approach and not make a big investment until there’s a resident with a need.

      For anyone building a new unit, I’d recommend running wire to accommodate full Level 2 charging on a 100A circuit.

      1. Colby says:

        The EV Charging at Multifamily Housing video is now on YouTube. http://www.youtube.com/watch?v=79ShT3YUVVA

        1. Hi Colby, yes, I attended the multifamily session in Santa Monica and it was very edifying. Unfortunately, it was a bit light on information for multifamily (apartment building) owners and was definitely more focused on condo owners and residents. Sad really because there were a number of apartment building owners like me in the audience who were desperate for information. Perhaps Plug In America will convene another panel to address the specific concerns of apartment building owners. . .

      2. Tom, thanks for your input. We are in the early stages of a building systems retrofit and I had never really thought about the electrical requirements for an EV charging station before. I’m grateful to you and to Plug In America for providing such good information.

    2. Anonymous says:

      For multi family use, you want as much charging speed as you can get. For the time being get 100 amp wire installed along with the 100 amp switches on the panel. But for the Charger itself, get 40 amp charger which is the higher end of the market right now. This will charge a car in 4-5 hours from empty or 1-3 hours for most uses and freeing up more time for others to use it. If you have two 20 amp chargers you will end up with people parked there for as much as 8-10 hours at a time which limits the amount of charging you can physically do. I’d put 4-6 parking spaces and a charger in the middle of each 2-3 parking spots so you can just unplug from one and plug into the other. I’d also make sure whatever charging station you use can show if the car is full or not so people don’t just randomly take each others charging away.

      1. Tom says:

        That’s a good point. Charging at multi-family dwellings may have higher speed charging requirements to enable sharing than home charging where there’s a dedicated charging station. Keep in mind that the charging rate is limited both by the charging station and the car. A 2011 Nissan LEAF can only charge at about 15A not matter how much current the charging station can supply.

        Faster charging vehicles are coming. The upcoming Ford Focus and later versions of the LEAF will support ~30A charging, while the Tesla Model S will support 80A charging. So it’s definitely good to be thinking about the future when trenching or running conduit – avoid redoing expensive install work if faster charging rates are needed in the future.

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