Electric car introduction
When we ordered an electric car, I was absolutely clueless about charging. What do we need to do before the car arrives? Do we need an electrician? What do we ask for? What kind of plug do we need?
It turns out we didn’t need to be anxious about bringing home our new EV. What we learned can give you confidence, too.
We started off by focusing on the type of connector – the thing that looks like a gas-hose nozzle that goes into the car – but gradually realized we should have started with the house, where we face the first choices.
Our house gets electricity from the utility, in our case PECO, and has grounded outlets. The typical wall outlet in the U.S. (110V, technically 120V) follows a standard from the National Electrical Manufacturers Association (NEMA). Many homes – including ours – have grounded outlets with two blades and one pin. This is a NEMA 5-15.
Our car will come with a home charger that plugs into that standard 3-prong outlet. This will “trickle charge” the car providing 3 to 5 miles of range for every hour of charging. All new electric cars in the US come with a charging kit , but kits, including the connectors, vary.
Let’s pause for a minute and talk about range anxiety. Lots of discussions about charging talk about going from empty to full as if charging a car were like filling up a tank. That analogy seems flawed. If our house had its own gas pump and a system that would pump the gasoline while we sleep, we would keep the tank full. Most nights a gallon or two would suffice. With the electric car, we intend to charge the car every night when electric rates are lowest. Trickle charging will provide about 30 miles of driving a day, which is more than we expect to need.
But what if we started to drive more? What options do we have? Faster charging requires more power – a 220V circuit (technically 240V) with sufficient amperage to charge the car.
How far will a charge take you?
Here is a rough estimate of how far one hour of charging at 220V will take you: 12 miles @ 20 amps, 18@30, 25@40, 30@50, 36@60 and 37@70 or 80.
For instance, a car with a 100-mile range will charge in 5 to 6 hours on a 30-amp circuit. These mileage numbers are based on the circuit’s amperage rating – the number on the breaker.
Keep in mind, some electric cars are more efficient, and will get better mileage than others. Technique also matters: A light touch on the accelerator may do better than a heavy touch.
Charging limit set by the car
You may think that the higher the amperage the better. That makes sense, but cars have a charging capacity. Each model is different. The Mini Cooper SE, which is small, has a low charging capacity – 7.2 kW – while a Lucid Air has a high capacity – 19-plus kW.
An 80-amp circuit is overkill if the car has a low charging capacity. A simple formula helps us decide what amperage we need. The relationship between amps, volts and watts is expressed as “Amps = Watts / Volts”. Volts will be 240, so the math tells us 30 amps is about right for a MINI (7.2kW) and the Lucid Air (19.2 kW) can handle 80. It doesn’t hurt to install bigger in case you need more power down the road.
Residential charging stations
At this point, let’s revisit the home setup. The typical 3-prong outlet will work with your car’s charging kit. Note that car manufacturers recommend you check with an electrician. If you decide you need 220V for faster charging, check with your dealer. Your kit may work with 220V or the dealer may have one that does. Otherwise, you can buy a charging station.
Charging stations cost between $500 and $1,000 and come in different amperages. They can plug in or be hardwired. The appeal of a plug-in charger is that you can take it with you if you move. If more than 50 amps are required, the station is typically hardwired to the circuit. An electrician can install the circuit and hardwire the station.
Charging station choices
If you browse a vendor such as Clipper Creek, you’ll see multiple offerings with similar specifications – for example, one will have a NEMA 14-50 plug, one will have a NEMA 6-50 and one will be hardwired. The 14-50 seems to be the most common.
Some homes may have existing 240V outlets incompatible with the charger. That’s easily fixed with an adapter.. All wires and plugs you connect should be rated at or below the circuit breaker rating. It’s OK to plug a 30-amp charger into a 50-amp circuit, but don’t plug a 50-amp charger into a 30-amp circuit. The charger could burn up.
Our big choices are done
We’ve now finished the house side. We selected our voltage – 110V or 220V – and our amperage – 15 to 80. Our charger is either plugged in or hardwired. Let’s consider how we connect to the car.
It turns out that in the U.S., the predominant connector is an SAE J1772. Teslas have proprietary plugs but the company offers a J1772 adapter.
On the road
Charging comes in levels: Levels 1 and 2 are residential grade; DC fast charging (sometimes referred to as level 3) is commercial. Level 1 is 110V; level 2 is 220V. When we talked about home charging earlier, we were describing levels 1 and 2.
Charging stations typically have only level 2 and DC fast chargers (level 1 is too slow). So what is DC fast charging?
DC stands for direct current. Your home uses alternating current (AC); battery-powered devices like flashlights and cell phones use direct current, as does your battery-powered car. A DC charger bypasses the AC-DC converter in your car to charge directly to the battery. The main benefit is charging speed.
DC plug standard - CCS
Just as with residential charging, there is a standard connector for DC fast charging. It’s CCS1 in the U.S.; CCS2 in Europe. The CCS1 standard combines the J1772 with a direct current connector.
There are exceptions to the standard – CHAdeMO and Tesla. CHAdeMO is primarily used by only two car makers – Nissan and Mitsubishi – and is being phased out in favor of the CCS standard. Cars with CCS1 cannot use CHAdeMO.
The other exception is Tesla, which does not use CCS in the United States. Tesla has a pilot program in Europe to let other electric cars fast charge at Tesla charging stations. If Tesla does open up its DC fast chargers, other EVs will need an adapter. On the flip side, newer Teslas can use an adapter to charge at CCS-equipped stations.
DC fast chargers range from 20 to 350 kW. At the low end, you can get close to 100 miles of range in an hour.
Limits for DC fast charging
DC fast charging, like 220V charging, is limited by the car. The direct current charging limit for a MINI Cooper is 50 kW; Lucid Air can handle 350 kW. Most cars will go from 0% to 80% in less than an hour. Charging slows down around the 80% mark, so it may not be worth waiting to get to 100%.
Where are the charging stations?
There are maps and apps to help you find charging stations. In addition to the commercial networks, car dealerships often have public chargers as do government offices, shopping malls and hotels. The charging network is growing rapidly.
ChargeHub and PlugShare map many such stations and the federal government has a site. Charging stations are operated by commercial vendors including ChargePoint, EVgo, ElectrifyAmerica and of course, Tesla.
- Be aware that charging stations are often selective in what they offer. Tesla stations do not have CHAdeMO or CCS1 chargers.
What we decided
We’re going to start with the kit that comes with the car and use an existing 110V outlet in our garage. This should be sufficient because we usually drive fewer than 30 miles a day. We’ll call out an electrician to get their blessing, but because there’s no load on the garage circuit in the middle of the night, we expect the existing outlet will be fine.
If we discover we are driving more than 30 miles a day, we’ll install a charging station hardwired to a 50-amp circuit. The service panel for our house is on a wall facing the driveway, so the wiring distance will only be a couple of feet. We won’t need a new outlet; we won’t need an outlet adapter. We never needed to worry about the connector that goes into the car.
In retrospect, it (almost) seems simple.
 NEMA Plugs courtesy of Orion Lawler – Creative Commons Attribution Share Alive 3.0 Unported
 According to “What Are the Different Levels of Electic Vehicle Charging,” Forbes