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How To Get the Best Home Charger for Your Electric Vehicle

Home EV Charging Station

The Right Choice Can Save Time and Money

The best charger for your home depends on several things. There's the type of electric 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.

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.

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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

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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.

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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

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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

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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.

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Who Makes Electric Vehicle Supply Equipment?

At present, there are a number of major manufacturers of home and portable EVSEs.

Re-Watt, 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.

Plug In, Charge Up

Once you've decided on a charging station and installer, check out our handy guide to saving money

onplug-in-vehicle charging bills. The article covers the varying kinds of billing rates plug-in-vehicle

owners can get from their local electrical utility