Automotive

EV charger 101: It’s not just plug-and-play

EV charger 101: It’s not just ...
Not all EV charging is the same. Some electrified vehicles have limits to their charge input and some plugs can handle more power than others
Not all EV charging is the same. Some electrified vehicles have limits to their charge input and some plugs can handle more power than others
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Not all EV charging is the same. Some electrified vehicles have limits to their charge input and some plugs can handle more power than others
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Not all EV charging is the same. Some electrified vehicles have limits to their charge input and some plugs can handle more power than others
This outlet type is both a 120V/20A and a 240V/20A with each outlet being 120 and both combined allowing for 240-volt output
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This outlet type is both a 120V/20A and a 240V/20A with each outlet being 120 and both combined allowing for 240-volt output
This is a common 30A plug found in many households in the U.S.
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This is a common 30A plug found in many households in the U.S.
This 240V/50A plug is found in some households and many industrial settings as the most common style of plug for 240/50 equipment such as EV charging stations
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This 240V/50A plug is found in some households and many industrial settings as the most common style of plug for 240/50 equipment such as EV charging stations
This plug is a combination J1772 Society of Automotive Engineers standard EV charge plug and a DC fast charging plug
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This plug is a combination J1772 Society of Automotive Engineers standard EV charge plug and a DC fast charging plug
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With the world shifting to electric vehicles, figuring out the best way to get a car charger for an electric vehicle installed is going to become common challenge for many of us. Here's a look at what’s involved, and what factors to consider, when it comes to installing an EV charger in your home.

Ed's note: This information pertains only to the United States and details will vary in other countries.

I recently decided to boldly go where no one where I live (that I know of) had gone before and installed an EV charging station at my home. I was initially unprepared for the complexities involved. Most homes in the United States have both 120-volt and 240-volt (commonly referred to as “110” and “220”) outlets installed. Nearly all of the plugs in our homes are 120V and the presence of a 240V is usually only in the laundry room and perhaps (if we’re lucky) the garage.

Having spent some time with an electrician, I learned that one plug is not like another. There’s more than one kind of 240V plug, for example, and they cannot just be swapped out at leisure. Then, doing some research on car charging units, I learned that there is a big difference between the power one type of plug can deliver over the other.

In the 240-volt department, there are two common types of power delivery options: 30-amp and 50-amp. The plug types are relatively standard in the US with a 240V/30A plug usually having three holes on a round receiver. Two of the holes are slanted slots, one as power delivery and the other as a neutral for return. The topmost hole is a round grounding plug. A 50-amp plug has three slotted plugs arranged like an upside-down spaceship from Space Invaders, two of which are power delivery with the other being a neutral return. The ground hole is, again, round and on the very top of the plug.

This is a common 30A plug found in many households in the U.S.
This is a common 30A plug found in many households in the U.S.

The 30A type is the most common in most US households, so if there is a 240V plug in your garage, it’s likely to be of the 30A variety (240V/30A). That can work for an SAE Level 2 charger (the most common, which use J1772 universal plugs) and for a slower Tesla-type charging unit. Most familiar with EV charging, however, will recommend a 240V/50A plug instead. I didn’t think it was much of a difference until I did some math.

Most electrical codes hold the maximum amount of power that a plug can deliver down to 80 percent so the circuit doesn’t overheat. For EV charging amperage is very important. A standard 240V/30A plug can deliver enough power to allow a 22.6-amp or 24-amp EV charger (commonly available types) to operate. A 240V/50A plug, however, will allow a 40-amp EV charger (also commonly available) to run. The latter will charge close to twice as fast as does the former. It makes a huge difference. Doing the math, it would mean a charge time reduction of about 70 percent, which in the real world would mean the difference between 18 hours to fully charge and 13 hours to do the same.

The cost to install either of these is usually about the same, though the wiring and plug for the 240V/50A is a little more expensive. Both are available off-the-shelf at any hardware store or parts catalog, so your electrician will have easy access to them. For my specific case, the difference in price was about $60 overall between the wiring, the plug, and the circuit switch for the 50A over the 30A option.

This 240V/50A plug is found in some households and many industrial settings as the most common style of plug for 240/50 equipment such as EV charging stations
This 240V/50A plug is found in some households and many industrial settings as the most common style of plug for 240/50 equipment such as EV charging stations

Finally, before we move on, it’s important to note that even higher amperages can be achieved, but those charging units will need to be hardwired to the circuit instead of plugged in, and are a very different ballgame. If your home has enough power coming in that you can set up a 70/80-amp circuit (allowing 50-amp utilization), that will allow charging at up to 70 percent faster than a 240V/50A plug-in charger.

Choosing a charging unit

There are a lot of charging unit options out there, ranging in price from around $200 to well over $1,000 ... and that's just the 240V/30A and 240V/50A varieties we’ve talked about here. Although a few cars do come with a charging unit included, most do not. The plug-in cord that most electric vehicles will come with likely plugs into a 120-volt household plug (which will literally require days to fully charge a battery-EV). Some have a 240 plug, but it’s usually a 30-amp and it may or may not include protective circuitry. And even if your EV has the correct plug for your setup, your friends or family that come to visit may not have the same plug for their vehicles.

Another consideration is whether your charging unit will be located inside or outside. If you have a garage that can fit your vehicle for charging, that is great and you’re going to need only an inside unit. If not, you’ll need a unit capable of handling the weather and of being secured or shut off when not in use to prevent theft. That limits the available units. Because I live in Wyoming and will be primarily charging in the driveway rather than inside a garage, I went with a unit that is certified to handle very cold temperatures. Including its charging cord, which is designed to retain elasticity in sub-zero temperatures.

The final consideration is cord length. Most chargers that plug in are designed to be mounted very near the outlet to which they’ll be attached. So outlet location and the length of that cord are important considerations. The charging cord, the cord which goes from the charging unit to your vehicle, should also be of a useful length. For example, because my charging unit is located inside the garage near its access doors, but most vehicle charging will happen outside of the garage, I opted for a 24-foot (7.3 m) charging cord so I can reach most port locations on any EV I might be charging.

An added benefit is that most of the recommended home charging units for EVs are connected and can meter the vehicle’s power input, meaning they can be easily programmed to take advantage of lower power rates at certain times of day.

The costs of a car charging unit and installation will vary according to circumstances, but most people can expect to spend at least $1,000 for an electrician if a plug must be installed and another $400 or more for a good charging unit.

If you are going to install a car charging unit in your home, it’s worth researching tax credits and other incentives based on where you live. Some cities and states offer tax credits for the installation and there is a federal tax credit you may be able to take advantage of as well.

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8 comments
8 comments
sidmehta
"There are a lot of charging unit options out there, ranging in price from around $200 to well over $1,000 ... and that's just the 240V/30A and 240V/50A varieties we’ve talked about here" OK but why do some cost 5 times more? How do I know which one suits me?
guzmanchinky
So until there is quick charging at most every gas station, I'm still out of this game. And I very much want an electric car, but I won't wait for more than 5-8 minutes to get back on the road again, and I live in a rental which won't allow me to modify the wiring in my garage...
*Joe*
guzmanchinky says "I live in a rental which won't allow me to modify the wiring in my garage" ... which makes me wonder how long until the government mandates that all rentals are required to provide chargers
DaveWesely
Excellent article. Guz, it shouldn't be long before apartment complexes start installing wiring to entice and keep renters. And 120v is adequate for typical commutes. If your garage has an opener, you've got the juice. Fast charging is only needed on road trips and unusual situations.
christopher
Nice article, but irrelevant to 99% of consumers - how many people drive 400 miles EVERY DAY ? Not to mention - unnecessary/excessive charge rates are almost certainly going to reduce battery cell lifespans. A standard overnight charge from a normal wall plug is going to give your battery at least 140 extra miles every day, plus 600 extra miles each weekend.
NMorris
guz, have you asked your landlord/agency about installing a charging plug? As others note, it's likely to be a selling/renting bonus in the future. They might well be interested if approached with that as a bonus.
joseph28
Decent article for newbies. I have one small quibble. In lieu of a 3 pin NEMA 6-50 outlet which has dual hots and a ground, a NEMA 14-50 outlet is more "modern" and it has dual hots, one neutral and one ground, so 4 wires in all. Next, the Tesla vehicles will charge at any rate and it is adjustable in the vehicle. The included power cord will allow for 32 amps of charge at 240VAC. With the hard-wired Tesla "Wall Connector", it will charge at 48 amps, and following the 80% rule that you mentioned, the breaker should be a 60 amp breaker. I suggest that it is best to bring the wires into a metal electrical junction box, then hang the outlet from that. This allows for more options in the future. If there are multiple Tesla vehicles in a garage (everybody's dream?), I believe it is possible to have up to four Tesla Wall Connectors on one circuit and somehow they magically co-ordinate charging rates and times so as not to overrun the circuit.
A-A-ron
If having to spend up to $1000 on a charging unit scares you, do not spend the $10k+ premium on an electric vehicle. You will not make the money back in saved gas money. The average American drives 14,000 miles per year. If you drive a gas guzzler that gets only 15mpg, that's 933 gallons, at $3/gallon, that's $2800/yr. If you get an average 30mpg, that's $1400/yr. The current market EVs take the place of a 30mpg ICE car, so you're really only saving about $1000/yr on gas money.

If you CAN afford the premium and are environmentally conscious, go for it, more "power" to you.