How To Get the Best Home Charger for Your Plug-In Car

The Right Choice Can Save Time and Money


  • Home Charging a Plug-In Vehicle

    Home Charging a Plug-In Vehicle

    Home charging is the most convenient way to replenish your plug-in vehicle's battery, and now there are many charging stations to choose from. | June 11, 2014

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When the first plug-in vehicles hit the market, buyers had little choice in the home charging devices they got. General Motors, maker of the Chevrolet Volt plug-in hybrid, and Nissan, maker of the Leaf battery-electric vehicle, each had partnered with a charging station manufacturer and installer.

Car buyers got a garage evaluation and installation quote before they took delivery of their vehicles. They bought the charging stations (usually through their car dealers) that the automaker recommended.

Fast-forward a few years and the marketplace has wrought its magic. Today, there are more than a dozen EV and plug-in hybrid (PHEV) vehicles on the market and more on the way. Owners and prospective owners of these plug-in vehicles can choose from dozens of home car-charging stations from more than a dozen manufacturers.

You can shop direct from the maker online, from various home-improvement retailers or via mass-marketing sites such as Amazon.com. Or you can do it old-school and go through your car dealer.

A recent survey of plug-in vehicle buyers by Ford Motor Company found that about half still use the dealer-supplied, one-stop service that provides the charging station and installation for one price. The other half now do their own shopping, both for the home charging station and for competitive bids from local electricians for installation.

Having loads of choices can help save money and cut down the time you'll spend charging that new plug-in car. But making the right selection from among the options also requires a little time in order to research the choices and to process and digest all those bids that come from comparison shopping.

The best charger for your home depends on several things. There's the type of plug-in vehicle you have or are planning to get. There are your plans for future plug-in vehicles. Your garage layout comes into play, as do your household electrical service and your charging patterns. Will you want to charge in the daytime, overnight or every time your pull into the driveway?

An electrician qualified to install home car charging stations can help you decide things like the amperage you'll need, the right circuit breakers to install, the best cord length for your situation and where to locate the charging station to minimize installation costs.

As a rule of thumb, expect to pay $600-$1,000 for a home car charging station. You can, of course, pay less or more. We'll get into the details later.

Installation costs also vary widely. A standard, problem-free home garage installation is usually somewhere between $1,000 and $1,500, but can be as little as a few hundred dollars or as high as several thousand dollars. We'll explain that wide range in more detail later, too.

Know the Right Name
First up, there's some lingo to know. In almost all cases, the charger isn't actually the thing you are going to buy and hang on the wall of your garage or carport. The charger is built into the car. (We'll get to the exception to this rule in a minute.)

That box with the colored lights, long cord and connector nozzle that you're installing is properly known as the electric vehicle supply equipment (EVSE).

It's OK if you call an EVSE a car charging station or home charger; almost everyone does. But by using the proper name for this unit, you'll be telling the electricians and salespeople with whom you're working that you know what you're talking about.

The EVSE is a vital piece of the charging system. It's a communications and safety device. It provides a point for anchoring the charging cord between the car's onboard charger and the building's electrical service. It also controls the charging current to keep the car's batteries from overheating. It can shut down the charging in the event of an electrical short, power surge, charging software meltdown or any other malfunction. That's important because an overheated charging cord could lead to a car or garage fire.

We said at the beginning of this section that the EVSE isn't the charger "in almost all cases." The exceptions are the rapid chargers that are being installed along various highway corridors around the country. These are also known as Level 3 chargers, and they are too big and complex to mount in a car. Level 3 chargers are packed into a free-standing case that's the size of a large refrigerator, or, perhaps not coincidentally, a gasoline pump.

All About the Connector
In addition to the communications and safety equipment, solid anchorage and a charging cord long enough to be serviceable, the EVSE supplies one additional and critical part: the connector or nozzle that plugs into the car's charging receptacle.

With the exception of Tesla Motors, which prefers to go its own way, carmakers and charging-equipment manufacturers around the globe have standardized the design of the nozzle, universally called a J1772 connector. Tesla owners can nevertheless choose to install an EVSE with a J1772 connector because the necessary adapter is provided with each car.

If you look into the J1772 nozzle's open end, you'll see five prongs with open centers, or ports. The top two are for carrying power. The large port in the bottom or 6 o'clock position is the grounding port. The smaller one in the 4 o'clock position is the communications port. The fifth port, in the 8 o'clock position, is the safety systems port.

Cord Length
The J1772 fitting delivers electricity and conducts communication between car and EVSE through an insulated copper cord. Most EVSE manufacturers offer several cord lengths, typically between 12 and 25 feet. Costs can go up considerably for every foot.

The best rule of thumb is to figure out exactly where the EVSE will be mounted, where the car will be parked and where on the car the charging port is located. Then buy an EVSE with a cord that's at least a few feet longer than the distance you'll need to span.

If your budget will stretch, buy the longest cord possible to give yourself room to charge while parked in various places in the garage and in the driveway. A long cord also will serve you well if you happen to buy another plug-in vehicle and its charging port is farther away from the EVSE than was the one on your initial vehicle.

Level 1 and Level 2 Chargers
Home-based charging equipment and most public charging stations offer two distinct levels of power.

Level 1 charging equipment delivers standard household current at 110 or 120 volts. It provides a very slow way of charging vehicle batteries. Level 2 chargers deliver power at 220 to 240 volts and at higher current, the same sort of power used for electric ovens and clothes dryers.

Almost all plug-in vehicles come with a Level 1 cord set charger in the trunk as standard equipment. It is a stand-alone charging cord with a standard household plug at one end, connected by a short cord to a small but heavy control box. A longer cord (usually 15-20 feet) snakes from the other end of the box and terminates in the J1772 connector. You can also purchase wall-hung Level 1 units if you prefer a more permanent setup.

Never use any sort of extension cord with a Level 1 cord set, even though you may be tempted by the short cord on the input end. Support or hang the control box near the socket you'll use instead.

The nice thing about Level 1 charging is that the cord sets are portable and can plug into any standard wall outlet. This means you can pretty much charge your plug-in vehicle anywhere you are.

The catch is that Level 1 charging is basically a trickle charge. The current simply doesn't flow very fast from a 120-volt household outlet. You generally gain just two or three miles of driving for every hour of charge time using a Level 1 cord.

You can get by on this if you own a plug-in hybrid, but it's insufficient as a primary means of charging a pure EV. Depending on model, the smaller batteries of plug-in hybrids require three to seven hours to fill with a Level 1 cord. Full EVs like the Ford Focus Electric and Nissan Leaf have larger batteries that can take 24 hours to replenish. And you're looking at three full days if you have an empty Tesla Model S P85 on your hands.

But a 240-volt circuit can recharge the same Leaf in about four hours. It can fill the P85 Tesla in 12 hours. So-called Level 2 charging is much quicker because it is done at higher voltage and at higher amperage. But it requires more rugged equipment and more robust garage wiring to handle the extra electrons and the heat they generate.

Level 2 EVSE charging equipment may cost more to buy, but there's more to be gained. There's the obvious time savings and the increase in convenience. And you may pay less for your electricity because many utilities offer time-of-day charging discounts for plug-in vehicle owners.

The purpose of these discounts is to encourage charging at night, when demand is down. But if you use a Level 1 charging station, you could plug in at midnight, when rates are lowest, and still be charging at noon the next day when time-of-use rates are highest. A Level 2 charger typically will get the job done without overlapping into more expensive rate slots.

Hard-Wired or Plug-In?
Until recently, the only Level 2 home EVSEs were wall-hung models permanently installed or "hard-wired" directly into the home's electrical service.

Now the industry also makes models that can be plugged into a specified 240-volt wall socket. These plug-in models are more easily portable if you move, but they cost about $100 more than their hard-wired counterparts. Such plug-in ESVEs are generally limited to indoor garage installations protected from the weather, though. Your local electrical code will probably require a hard-wired installation if you plan to situate the EVSE outdoors.

One major manufacturer recently introduced a dual-purpose Level 1 and Level 2 portable cord set that doesn't require a wall-hung control box. Several boutique manufacturers also offer Level 2 cord sets. Typically, though, they are slower than the wall-mounted models, and you'll still need the proper wall socket and circuitry to supply them.

Sizing Your EVSE
Because the chargers for both Level 1 and Level 2 charging are built into the car, the maximum rate at which the battery can be refilled depends on the capacity of the charger the automaker put under the hood as well as the amount of power the EVSE can supply.

The key elements in charging speed are:

  • The capacity of the car's onboard charger (kilowatts or kW)
  • The voltage of the EVSE (volts)
  • The amperage of the EVSE (amps)

Car Charger Capacity
The onboard charging capacity of a given electric vehicle is hard to pin down because this important vehicle specification isn't always easy to find. But it's an important thing to know when choosing your EVSE.

All plug-in hybrids today use 3.3 kW onboard chargers, which means they can take on a maximum of 3.3 kilowatt-hours of electricity every hour they're connected to Level 2 equipment. A handful of smaller pure electric vehicles use 3.3 kW chargers, too. These include the Chevrolet Spark, Mitsubishi i MiEV, Smart EV, all versions of the 2011 and 2012 Nissan Leaf and the base model of the 2013 (and newer) Nissan Leaf.

Most other battery-electric cars now use 6.6 kW chargers, which doubles the maximum intake to 6.6 kilowatt-hours per hour. That also means they'll generally fill up in half the time, too. Cars with 6.6 kW onboard chargers include the BMW i3, Ford Focus Electric, Honda Fit EV and the medium and high trim levels of the 2013 and newer Nissan Leaf.

Toyota's RAV4 EV and the Tesla Model S come outfitted with a 10 kW charger, and the Tesla Model S provides buyers the option of a second onboard charger to double the maximum intake to 20 kilowatt-hours of battery charge per hour.

Of course, the cars with the higher-capacity onboard chargers need a more robust ESVE that's connected to a higher-amperage garage circuit to take full advantage.

Voltage and Amperage
The nominal design voltage for Level 2 charging equipment is 240 volts. But electrical service varies from place to place. It could range down to 220 volts, and some commercial supplies run at 208 volts. Level 2 charging equipment works across this range.

The other key element is the capacity of the circuit supplying those 240 volts. Amperage is the crucial unit printed on your home's circuit breakers, on every fuse you've ever changed, and it's the electrical unit that describes the maximum flow rate a given circuit can supply. All Level 2 EVSEs are built to work at 240 volts, but they are sold in a variety of amperage ratings to suit the needs of different cars.

Common Level 2 output ratings are 16 amps and 30 amps, but there are others in between and ranging all the way up to 80 amps.

Which one should you buy? Electrician and EVSE specialist William Korthof recommends buying an EVSE rated for the most amps your budget will allow. Prices go up in lockstep with amperage increases, though, both for the unit itself and the wiring necessary to support it.

"You may not need it all with your first plug-in car," he says. "But when the time comes to get another one, it may have a more powerful charger and you'll avoid having to buy a new EVSE to take advantage of it."

Korthof recommends a 30-amp EVSE as the minimum. If you are buying a Tesla — or hope to buy one in the future — you'll need at least a 40-amp EVSE to take full advantage of its quicker charging capacity. The 80-amp hot-rod models are only worth considering if your Tesla is equipped with the twin-charger option.

The circuit breakers that must be installed in your home's fuse box to deliver current to the EVSE must be rated 25 percent higher than the rated output of the charging station. A 30-amp (sometimes 32-amp) station needs a 40-amp breaker. A 40-amp station needs a 50-amp breaker. The 80-amp unit must be backed by a 100-amp breaker.

Additionally, the wiring that runs from the circuit breaker to the EVSE also must be properly sized to handle the amperage and the distance from the EVSE to the breaker. That's another reason why it's crucial to hire an electrician to do the installation.

Doing the Math To See What an EVSE Will Deliver
Why does Korthof recommend a 30-amp unit? It's fairly easy — especially if you have a calculator on your smartphone — to figure out the maximum amount of juice that any EVSE will deliver.

Simply multiply the device's rated amperage by the nominal line voltage (240 volts) and divide by 1,000. The answer is the maximum number of kilowatts the charging station can deliver. It may be more than your car's onboard charger is rated for, but that's no problem: The onboard charger will only draw as much as it thinks the battery can handle.

For example: A 30-amp Level 2 EVSE can deliver up to 7.2 kW (30 x 240 =7,200/1,000 = 7.2), while a 16-amp model can deliver 3.84 kW (16 x 240 = 3,840/1000 = 3.84).

We can see that the 30-amp EVSE's 7.2 kW output comfortably exceeds the needs of an EV with a 6.6 kW onboard charger, but the 16-amp unit and its 3.8 kW output can only meet the needs of a car with a 3.3 kW onboard charger.

To Korthof's point, the larger 30-amp EVSE will safely charge a car that has a 3.3 kW onboard charger, even though a 16-amp unit will do. The main advantage is you won't have to upgrade your EVSE if you decide to trade in your car for a newer EV with a faster 6.6 kW onboard charger in the future.

What Will the Electric Vehicle Supply Equipment Cost?
The price of an EVSE depends on several factors. There is its capacity, the length of its cord and whether it is indoor-only or rated for outdoor installation as well. There's the overall ruggedness of its case, cord and J1772 connector. Finally, there are the bells and whistles with which it is equipped, and even the brand name.

The days of free charging stations are pretty much over. The federally funded installation programs have ended and with the exception of the new Cadillac ELR plug-in hybrid, automakers aren't giving away charging stations with each purchase.

As a rule of thumb, expect to pay between $600 and $1,000 for an EVSE rated at 30 amps or more. You can get lower-rated charging stations for under $400, but you may soon wish you could get a faster charge than they'll allow. And you can spend $1,500 on fancy WiFi-enabled models that let you remotely control charging times and monitor charging progress. But most EVs and PHEVs these days come with remote control features and mobile phone apps that let you control them.

Why pay to duplicate the functions on a "smart" EVSE? It may be the best way to track and record exactly how much electricity your car is consuming with each charge. The car's dashboard kWh gauge, if it has one, will only tell you what the battery puts out. A smart EVSE will tell you how much electricity it dispensed to replace that electricity, and that number includes the inevitable charging losses that accompany the battery filling process.

Level 2 portable cord sets typically cost less than wall-mounted EVSEs, but they also tend to have lower amperage ratings and thus provide slower charges. Prices for the several models on the market today range from $395-$1,027.

Installation
Buying the charging station is only part of the cost, however. You'll need a qualified electrician to wire things up, too. Some locales require permits and inspections.

An exception is if your garage already has a dedicated 240-volt plug receptacle of the proper type installed. That would let you buy a portable EVSE, hang it on the wall and plug it in yourself.

For both hard-wired and plug-in Level 2 EVSEs, you'll need to install the properly sized circuit breaker in the fuse box and run wiring inside conduit from the box to the EVSE's location.

Then you either connect the EVSE directly or, for plug-in models, install the proper receptacle so the EVSE can be plugged in. The EVSE's specifications sheet will tell you which type of plug it has. Most are either NEMA 6-50, the type used for welding equipment and for most 240-volt garage outlets, or a NEMA 10-30 or NEMA 14-30, both used for residential clothes dryers. All are pictured in this online NEMA reference chart. NEMA is the acronym for National Electrical Manufacturers Association, which sets standards for all sorts of electrical equipment.

Costs will vary by prevailing fees for electrical work, by the amount of work that needs to be done and the cost of any necessary permits.

If the best place for your EVSE is on the interior garage wall directly behind the exterior-mounted fuse panel, there will be very little wire to run and the cost could be just a few hundred dollars.

If the electrician has to run wire through the wall and then 20 feet away to the EVSE location, wrapping the conduit around a corner or two along the way, the cost could be hundreds more.

And if your house is an older one and simply doesn't have a big enough fuse box and you have to upgrade your electrical service, you're typically talking well in excess of $2,000.

Who Makes Electric Vehicle Supply Equipment?
At present, there are a number of major manufacturers of home and portable EVSEs.

Aerovironment, one of the early suppliers, makes both wall-mounted EVSEs and cord sets and is the preferred supplier of several major plug-in vehicle manufacturers.

Blink, which had problems early on and is now owned by The Car Charging Group, has a new wall-mount home station. Bosch is a favorite of German carmakers.

Clipper Creek makes EVSEs with J1772 connectors but also is the preferred supplier for Tesla. Delta, a maker of wall-mounted units, has products available online. Eaton is a major electrical equipment supplier.

Electric Vehicle Institute is an online supplier. EVoCharge makes an outdoor-rated home EVSE with a retractable cord and a reel that can be mounted separately. in locations such as an overhead joist in a garage. EVSE Upgrade converts carmaker-supplied Level 1 cord sets to operate as Level 2 charging cords as well.

General Electric makes wall-mounted stations for home use. Leviton, Schneider Electric and Siemens are major electrical equipment suppliers now in the home charging station market.

Where To Buy
Some of the manufacturers listed sell directly to the public via their Web sites. Others list retailers (and often their recommended installers) in the regions where they market their products.

Additionally, some EVSEs can be ordered on Amazon.com and eBay, and Home Depot and Lowe's also sell a variety of home charging stations via their Web sites.

Plug In, Charge Up
Once you've decided on a charging station and installer, check out our handy guide to saving money on plug-in-vehicle charging bills. The article covers the varying kinds of billing rates plug-in-vehicle owners can get from their local electrical utility

If you haven't already bought or leased the car, use our reviews of EVs and PHEVs, and our car-buying tips and car leasing tips to help make shopping easy.

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