One of the big advantages of driving electric is charging your car–“filling up”–at home instead of going to a gas station. For most people, 90% of their charging is done at home.
To charge at home you need an EVSE (Electric Vehicle Supply Equipment). That’s jargon for a charging system that includes a box with a big electrical switch, a cable, and a plug that fits into a port on your car. The actual “charger” is in the car. The EVSE simply provides electricity to the car’s charger (inverter) after a “handshake” with the car’s computer.
There are lots to choose from. Some are portable. Some must be mounted on the wall. Some are made in the USA. Many are made in China. To confuse matters further, there are many choices for how fast the EVSE can charge your car.
We have two: a wall-mounted EVSE, and a portable one for carrying with us on road trips. Our wall-mounted EVSE is made by ClipperCreek, a California manufacturer. Our portable or mobile charge cable is made by Tesla and modified by a California start-up, QC Charge.
Why we have two and why we chose those two takes a bit more to explain.
240 Volts vs 120 Volts
In North America, you want to charge at 240 volts. This just makes your life of driving an EV simpler.
All EVs come with an emergency EVSE suitable for trickle-charging the traction battery on a household receptacle at 120 volts. We have one in our Chevy Bolt EV. So you might say we have three rather than two EVSEs. However, I don’t count the EVSE that came with the Bolt. I haven’t even taken it out of its plastic bag.
Typically, EVSEs that come with an EV are painfully slow, delivering about one kilowatt (kW) per hour. It would take 60 hours to charge the 60 kWh battery of a Chevy Bolt from zero to full–two and one-half days–on a 120-volt outlet. These will do in a pinch until you get a dedicated 240-volt EVSE installed, but they are not a permanent solution.
Some auto companies are shipping EVs with portable EVSEs capable of 240 volts. Others provide portable EVSEs that can easily be modified to charge at 240 volts. These could be used on a regular basis to charge your EV with the exception noted below.
Indoor & Outdoor EVSEs
All homes in North America are served by 240 volts. Electric dryers, hot water heaters, air conditioning equipment all require 240 volts. However, there are several different kinds of 240-volt receptacles. These look much different from the 120-volt household receptacle and take a special plug.
If the EV you own came with a portable EVSE capable of 240 volts, you could use this as a permanent charge system inside an enclosed garage. If the garage is not enclosed or if you have to use the EVSE outside exposed to the elements, the portable charge cable wouldn’t be satisfactory on a permanent basis.
For any application where the EVSE will be exposed to the elements, the charging system box must be “hard-wired” to the home’s circuits. This requires an electrician. In most places, the portable EVSE can’t be plugged into a receptacle all the time if it’s outdoors.
EVSE’s are rated by the current in amps (A) they can safely deliver at 240 volts. Multiplying amps times volts gives the power rating of the device. An EVSE providing 32 amps at 240 volts will deliver 7.7 kW to the car.
When 40 Amps is not 40 Amps
In North America, most local authorities incorporate the National Electrical Code (NEC) and its requirements when approving any electrical installation below 600 volts. The NEC exists to prevent electrical fires. The NEC affects how EVSEs are used and what they can do.
Circuits must be able to carry both a specified voltage and current without overheating or otherwise failing. One of the criteria is the amount of current in amps a circuit can carry briefly; say to start an air conditioner compressor motor, and what the circuit can carry continuously.
The nameplate rating is what the circuit can carry briefly. A 40-amp circuit is designed to carry 40-amps briefly before tripping the circuit breaker.
However, the same circuit can’t carry the same current continuously without unacceptably heating the conductors. To stay on the safe side, the continuous current rating must be less than the nameplate rating.
The NEC standard for continuous current is 80% of the instantaneous or nameplate rating of the circuit. Thus, a “40-amp” circuit is rated to carry only 32 amps continuously.
An EV is more like a toaster that’s on for four to six hours than it is a refrigerator that turns on its compressor motor then turns it off after a few minutes. So a ClipperCreek 40-amp EVSE is actually limited to 32 amps.
Thus, it’s always wise to know if the EVSE you’re buying is “rated” at 40 amps or is “delivering” 40 amps. Confusingly, the latter is a 50 amp EVSE. Vendors don’t always make this clear.
What We Use
The EVSE that we use is a no-nonsense device made right here in California by ClipperCreek. It doesn’t do anything more than deliver electricity to the car when it determines it’s safe to do so.
Our ClipperCreek HSC 40 EVSE is mounted on the wall of our house. It is rated at 40 amps, 240 volts. What this means in practice is that our ClipperCreek can charge EVs up to 32 amps continuously. (For more on this, see Electric Vehicle Charging Stations or EVSEs.) Thus, our EVSE can supply 7.7 kW. The Chevy Bolt can draw the full 32 amps but only delivers 7.2 kW to the traction battery because of losses in the inverter.
Our HSC 40 has worked flawlessly for six years. I recommend ClipperCreek. They were one of the pioneers in EVSEs and have been at this a long time. They even produced the charging stations for GM’s ill-fated EV1.
ClipperCreek’s 40-amp HSC 40 comes with 23 feet of cable and a J1772 SAE connector for plugging into the appropriate port on non-Tesla EVs. The J1772 connector is the universal 240-volt plug for all EVs in North America except Tesla.
Note: In 2025 this will change. Most new cars sold in North American will begin using the Tesla connector instead of the J1772. The latter plug will be around for a very long time, but new cars will begin using the Tesla connector (plug).
Portable or Mobile EVSE
For us, having a portable EVSE capable of 240 volts was part of the cost of owning an EV. It was an anticipated expense. It was essential when we first began driving electric six years ago, less so now. Many of the places we wanted to visit didn’t have fast chargers–or chargers of any kind–then. But RV parks and some hotels did have places to charge at 240 volts. We could use our portable charge cable to charge in these out-of-the-way places, and we did. We traveled all over Southern California with an EV that had limited range.
We bought a Jesla mobile charge cable from QC Charge. Jesla rhymes with Tesla for a reason. The Jesla is a Tesla mobile EVSE modified to work with the J1772 standard plug required by all non-Tesla EVs. It’s a surprisingly compact package that can deliver up to 40 amps continuously at 240 volts, giving it a 50-amp rating.
It wasn’t cheap. QC Charge calls it a “premium” charge cable with reason. Jesla’s $1,000 cost was nearly three times that of EVSEs from ClipperCreek, but it can deliver all the power our Chevy Bolt needs.
QC Charge has dropped the price on the Jesla since we bought ours and now also offers a Jesla Jr (32 amp continuous) for $600.
At an RV park, where we can draw the full charge our Bolt is capable of, we can charge in nearly half the time necessary with the portable units from ClipperCreek. When you have a long day of travel ahead of you, charging faster may be worth it. It is to us.
Jesla comes with a small padlock. Using the padlock gives you peace of mind that someone’s not going to walk off with your expensive hardware while you’re waiting for your car to charge.
ClipperCreek builds a 20-amp portable charge cable in California that can deliver 16 amps at 240 volts continuously to an EV for $400. They offer a 30-amp version for $500. Check ClipperCreek’s web site for EVs for residential use. They also offer used EVSEs.
Note: ClipperCreek is now owned by Enphase and assembly is being offshored to Mexico.
To reiterate, if you have an enclosed garage with an outlet providing 240 volts, you can use one of these portable charge cables for charging your car. Then, when you head out on a road trip, you can take the portable charge cable with you in case you should need it.
For more on what we use, see the following links.