A Beginner’s Guide to Residential Electric Vehicle Charging

So you’re about to buy your first plug-in car and you’re a little confused about the whole “home charging” thing – what it means, what equipment you should buy, and how to install everything.  Perhaps you even took the plunge and purchased your plug-in car without even realizing you may need to install home charging equipment for your vehicle. Not to worry, choosing a charging station (also known as “EVSE,” or “electric vehicle supply equipment”) for your home isn’t really all that difficult.

Decisions, Decisions

There are a lot of home charging stations available out there to consider, but the first thing you to do is decide if you even need to purchase one. Every battery electric vehicle (BEV) and plug-in hybrid electric vehicle (PHEV) comes with a portable 120v, level 1 EVSE. Tesla vehicles come with a Universal Mobile Connector (UMC) which serves as a portable level 2 EVSE. It can charge on a single phase, 120v & 240v, or three-phase 208v electric supply. If you purchased a Tesla, the supplied UMC is all you need for charging at your home. Simply have an electrician install a NEMA 14-50 outlet where you want to charge the vehicle at your home and you’re all set.

It’s not quite as easy if you have an electric car from any of the other manufacturers. As mentioned above, every EV comes with a portable 120v, level 1 EVSE. These units will charge your vehicle from a regular household outlet. However, since they only accept 120 volts, the amount of power they deliver is very low. A typical EV will charge at a rate of about 4 miles per hour while using a 120v portable EVSE.  Therefore, even if you charge the vehicle overnight, you may only replenish 30 to 40 miles of range.

If you have a PHEV, that may be all you need. PHEVs have smaller batteries than BEVs, since they also have gasoline engines to provide additional range once the battery is exhausted. Many PHEV owners choose to use the level 1, 120v portable EVSE as their daily charger. If that suits your needs then that’s fine, but consider this first:

Have an electrician inspect the home outlet and circuit you’ll be plugging the 120v EVSE into. Often, especially on older homes, outlets in the garage don’t get much use and can be exposed to humidity, dust and other contaminants. The connections may be loose from years of use, and aren’t ready to be used for many hours every day, now under a high load.  In most cases, the electrician will just inspect it and tighten the connections. It’s only a couple dollars for a new receptacle so you might as well ask them to replace it while they are there – that way, you know it’s new and ready for the task of daily home charging.

However it you have a BEV, or a PHEV with a larger battery, you will most likely opt to install a level 2, 240v EVSE.  These units will charge your car up to six times as fast as the 120v level 1 portable EVSE will, depending on how robust your car’s onboard charging equipment is. Remember the actual charger is built into the car and that is what dictates how much electricity the vehicle will accept. The EVSE is simply a device to safely deliver the electricity to the car. When you plug the car in, the car communicates with the EVSE, asking it how much electricity it can deliver. Then the car calls for the most electricity it can accept, and the EVSE can safely deliver that amount.

Deciding which level 2 EVSE is the right one for you will depend on a couple things:

• There are level 2 EVSEs that cost as little as $300 and some that cost as much as $2,000 and the more expensive one’s aren’t necessarily better.
• There are features like WiFi connectivity that some of the newer EVSEs offer. This allows the owner to track their electricity use, remotely see how much energy the vehicle is taking, and calculate the real cost to charge the car.
• Hardwired, or pluggable? Many EVSEs come in a hardwired version and a pluggable one. The hardwired units are permanently installed in your home and the pluggable units plug into a 240v outlet, just like an electric clothes dryer or range. The benefit of having a pluggable EVSE is you can take it to other locations like a summer home or a relatives house and plug it in there provided they have a 240v outlet to use
• Some level 2 EVSE accept only 16 amps, while others can accept up to 80 amps. You need to check how many amps your car can accept to match it with an EVSE that can deliver at least as much. You should also keep in mind your next plugin car may accept more amps, so it’s prudent to consider installing one that will future-proof your garage. We at EVSpace believe that an EVSE that can deliver 40 amps is a good balance between cost and delivering the high power for larger battery electric cars.
• Installation Cost. The cost to install a level 2 EVSE can be as little as a couple hundred dollars and as much as several thousand dollars. It all depends on your electric service and the location of where you want the EVSE installed. That’s why, before you even buy a level 2 EVSE, it’s probably based to have a professional inspection of your home’s electrical capabilities (see below).

Inspect, Then Connect!

We’ll finish up with the first thing you should do if you want to buy a level 2 EVSE, and that’s have a licensed electrician inspect your home.

Any level 2 EVSE that you purchase will require a dedicated 240v circuit of at least 20 amps. Most common EVSEs require a 40 amp dedicated circuit, and if you wanted to install a 40 amp EVSE, than you’ll need a 50 amp circuit. That’s because as per the electric code, the device cannot draw more than 80% of the circuit. This is for safety, so that the wiring and outlet doesn’t overheat and possibly cause a fire.

Some older homes don’t have the extra, unused capacity in their service panel to add the new circuit for the EVSE. If that’s the case, the owner needs to upgrade their service that can cost a few thousand dollars.  If there is room, then there’s no problem, but you should know this before you buy the EVSE, or the electric car, for that matter.

So plan ahead, have a home inspection by a licensed electrician and you’ll know exactly what you’re in for before you get your electric car.

Next, be sure to check out our article detailing what to consider once deciding to purchase a home charging station (EVSE).