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Keeping Your Electric Vehicle on the Road

Basic chargers will top off the battery, but newer technologies have far more to offer

Fast charging stations like this one in a grocery store parking lot are becoming more common, but most electric vehicle owners will do the bulk of their charging at home. Photo courtesy Scott Gibson.

Sales of electric vehicles in the U.S. have been climbing steadily in the last decade, rising from less than 18,000 in 2011 to more than 300,000 two years ago. Although that’s a drop in the bucket compared with total new vehicle sales, that still leaves a lot of people learning how to make the conversion from gas pump to battery charger.

Car chargers fall into three broad categories: basic Level 1 chargers that run on 120-volt household current; Level 2 chargers that use 240-volt current and higher amperage for faster charge times; and Level 3 or direct current fast chargers, which offer the quickest of all refill times. Level 1 and Level 2 chargers are for home use. DC fast chargers, which convert AC power to DC within the charging station and deliver DC power directly to the battery, are both expensive and operate on three-phase power; and they are not intended for residential use.

The fundamentals are simple. You plug your electric vehicle (EV) into a charger, wait until the battery is topped off, and drive away. Charge times vary by vehicle, how depleted the battery is when you start, and the power of the charging device. But the technology is rapidly evolving. WiFi Level 2 chargers give drivers the means to control charging precisely, track energy use, and take advantage of time-of-day electricity rates. Even more flexible are bidirectional charging devices. This emerging technology will allow a two-way flow of electricity between the car’s battery and a house, a business, or the utility grid, transforming electric vehicles from simply a mode of transportation to a rolling source of power.

Level 1 and Level 2 chargers are manufactured by a number of companies, are widely available, and include a number of Energy Star models.

Charging at home

The fear of running out of power on a long-distance…

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6 Comments

  1. Charlie Sullivan | | #1

    This is a great article, with a nice combination of practical advice for prospective EV owners and a good overview of what the future may hold.

    A couple of tips to add:

    1. The website/app http://aBetterRoutePlanner.com is great for planning trips and seeing what charging stops might be needed, or, for vehicle shopping, seeing how a vehicle you are interested in will do on longer trips that you might use it for.

    2. When you are shopping for a level 2 home charger (EVSE), it's important to look for a unit that is safety certified by UL (or ETL, supposedly equivalent). There are lots of cheap ones on Amazon that don't have that certification, and tests have shown that some are missing the basic safety functions that keep a user safe from electric shock, especially connecting outdoors. Others have overheated and could pose fire hazards. I would consider a proper safety certification essential for a piece of equipment like this whose primary purpose is to keep you safe.

    3. If you are charging outside and live in a cold climate, a cord that stays flexible in the cold is also nice to have--ChargePoint seems to be the leader in this regard, as well as having top performance on the Energy Star criteria, and having a good reputation for reliability.

    As for the question of going bidirectional and drawing power out of the vehicle's charge port, figuring out the technical, financial and regulatory protocols for V2G may take some time, but I think that we'll see that capability used for backup power as the initial application--sometimes called "vehicle to home" (V2H). If you've got a 50+ kWh battery sitting in your driveway and there's a power outage, it would be nice to take advantage of that to run your refrigerator for weeks, or some heat pumps for days.

    And for builders builders the ability to tap into a vehicle battery to power tools on a job site is also going to be a convenient capability.

  2. Antonio Oliver | | #2

    I've wondered if frequent high rate battery charging reduces the lifetime of an EV's battery. Can someone comment on this subject?

    1. Charlie Sullivan | | #3

      Frequent high-rate charging can reduce the lifetime of an EV battery. For that issue, any level-2 charging is slow charging and is well below there being any consideration along those lines. For dc fast charging (DCFC), charging at, for example, 50 kW is gentler on the battery than charging at 100 kW. Also important is the cooling system for the battery--better designs use liquid cooling and keep the battery cool during a fast charge, and the heat is a lot of what can degrade the battery.

      The Chevy Bolt, for example, uses liquid cooling and limits DCFC to 50 kW. Reports from users who have done frequent fast charging and monitored battery capacity over many miles and charge cycles are that the degradation is barely measurable even after heavy DCFC use. It seems that GM chose to limit DCFC to 50 kW to ensure that result, even though some drivers would prefer to have a faster DCFC capability. I'm pretty happy with the 50 kW DCFC as I like to take frequent breaks on long drives anyway.

  3. Dan Phillips | | #4

    Another route some utilities are going to "manage" EV charging are Time of Use rates. Either for the whole home, or for a separately metered circuit specifically for the EV. Corn Belt Energy in Illinois is piloting a whole house Time of Use rate, reaching out to their members who own EVs. The overnight, off peak energy is a fraction of the typical retail rate allowing those members to save money when they charge at night, and saves them by avoiding those cars getting plugged in once the member typically "gets home" as the evening peak is starting to hit.
    Here in Indianapolis, IPL offers an EV-specific rate for a separately metered EV charging. I've been averaging well below $.04/kWh on my bill, compared to ~$.11/kWh as the normal retail rate.
    If I do need to charge during peak hours, I can, but I really want to as the rates can get pricy (roughly 2x to 3x the normal retail rate).

  4. Mark Walter | | #5

    WITHIN the home electrical system we are seeing the evolution of appliances (including automobiles) that actually run on DC (furnaces, water heaters, heat pumps, LEDs.) Electrical current is frequently being converted AC/DC. There is probably substantial loss related to this conversion process. Seems like we are approaching a time when our homes should have a major DC system for PV generation/storage, heating/cooling, EV charging and lighting as well as a minor AC system for (relatively low consumption) consumer products.

    1. GBA Editor
      Martin Holladay | | #6

      Mark,
      I've lived in a 12-volt DC house for over 40 years. I've never heard of a DC water heater. (That said, you can buy DC elements that allow you convert an AC water heater to a lower voltage of DC. This is fairly easy for resistive loads like water heaters.)

      DC appliances have been around for decades -- selling to RV owners.

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