Terren Peterson


How Prepared is the Charging Network for the Growth in Electric Vehicles?

A 1992 Converted Escort Wagon — courtesy of AVTC

I’ve been waiting for electric vehicles to overtake gas burning vehicles for 25 years. In college, I participated on the very first HEV Challenge, working on the UIUC team before graduating with my degree in Electrical Engineering. Given the tremendous progress at the time and the talented engineering students I saw working on it, I was convinced that change was just around the corner. Internal combustion engines were going to go away, and the hybrid technology would serve as a bridge until battery technology caught up. I even struggled with the decision to enter the workforce versus stay in graduate school to work on this project. This was where the future would be — right? That was the Fall 1992.

Arrival of Tesla Motors — Roadster Launch in 2008

I never lost interest in electric cars, and was a huge fan of Tesla from the first time I laid eyes on one. While the Roadster was way out of my price range, I followed every detail of its launch. While some were surprised that an EV could perform this well (248 HP, 244 mile range), it was a long wait for me.

My daughters science fair entry in 2008

Now the initial Roadster model only produced 500 vehicles, so there was no need for a massive distribution network of charging stations. Competition at the time was focused on hybrids, and specifically parallel drivetrain technology. Cars such as the Toyota Prius and Chevy Volt were cars that could run with both an electric and gas engine connected to the drivetrain.

The vehicle that we worked on in the early HEV competitions was a series hybrid. With series, gas driven engines were used to charge the batteries, not directly drive the tires. This is much closer to the dreams I had of an EV future.

Relying on parallel technology also meant that immediacy for building a distribution network for electric cars was minimal. Running out of energy in the batteries with these cars meant that the fuel rating might go down, but the car would still travel. So not as much demand for charging on the go.

The Model S — the Birth of Mass Production EV’s

After the successful Roadster launch, discussion moved towards a more affordable car — one that would expand the recognition of EV’s as well as the need for a distribution network to fuel them.

My wife and I visited a dealership in DC in 2011 to check out an early version of the Model S, and the initial models began delivery in 2012.

Tesla Showroom in 2011 with Model S Preview (aka Signature Series)

Growth followed, and by late 2015, there were 100k Tesla EV’s on the road — beginning to create a surge in demand for charging stations.

Growth in Tesla Model S & X Deliveries

Taking the Plunge

A year ago, I finally made the leap and bought one. It was delivered in April 2017, and I have been learning more about the daily operations and charging of an EV. This has given me a first person view on the state of the distribution network, and I’m thrilled to finally have my own EV!

My 2017 Tesla Model S

Home Charging is a Must

As part of owning an EV, you need to become familiar with the electrical wiring at your home to understand options. For our house, we hired an electrician to add a 240V wall outlet in our garage ahead of taking delivery of the car. This is similar to what you would need for any large appliance — an electric dryer, dishwasher or fridge that runs on 240V. Given the significant draw on this outlet, we added it as a separate circuit to the breaker panel.

Our house was built in 1994, and there was ample capacity for us to do this modification, and the electrician handled the review with the county inspector. It was an extra cost (around $1500) on top of the vehicle but well worth the investment. Long term it will be like adding a sprinkler system that adds nominal value to the home to offset the expense. I assume if people are building houses today that they naturally are including this into the design.

With the car, Tesla provides a cable that connects from a standard 240V outlet, and with our configuration it can completely charge the battery in just 4–6 hours. Once the charging routine is established, it is very easy, and the plug is straight forward (see photo below).

Our electric bill didn’t see a significant jump once I started charging at home, and the retail rates are more than offset by no longer paying $2+/gallon in gasoline.

Standard coupling for Tesla charging

High Speed Charging — Works!

While ramping up EV production, Tesla has built out a network of high speed charging stations across the US. These come in very handy when commuting out of town. The coupling is the same as above, but the speed at which energy is transferred is much faster. If I just need to “top off” by adding energy for 50–100 miles, it typically takes just 10–20 minutes. I travel regularly in the Virginia/DC/Maryland region, and now have been to most of these supercharging locations. Most have food or retail nearby, and it has a similar feel to going to a gas station.

My car recharging at a high-speed Tesla facility in Maryland

Independent Site Charging?

Finding a high speed charging station on the Tesla network isn’t always convenient. This is where things get a little complex, but an ecosystem is developing that all potential EV owners should monitor.

There are charging stations — both free and for fee — that you can tap into. The largest is called Chargepoint, and they have a great mobile app that shows the available locations and status. The price for the electricity is much higher (3–4X) what my local utility charges at home, but they are convenient. The internet has many other resources to show charging locations. Some offices, hotels, and Universities provide charging facilities independently, and sometimes for free.

Given that charging at a neutral location means that the service should work for all EV’s — not just the Tesla. There are adapters that come with the Tesla, including the one in the photo below. It is for the SAE J1772 that is the most common interface with these types of locations.

Coupling for SAE J1772 connection

Epic Charger Fail

Now I have had a few bad experiences when trying to charge on the road. The worst was a recent stay at a hotel that provided high-speed charging, but when I pulled into the stall, I saw a new adapter — the dreaded SAE Combo (photo below).

Coupling for a SAE Combo (CSS) charger

After spending an hour with the hotel maintenance staff, calling the support number on the charging unit, and talking to Tesla support, here is what I figured out.

1 — This port is a new “standard” that enables high capacity charging.
2 — It doesn’t work with the adapters I got when I bought my Tesla.
3 — Tesla doesn’t sell an adapter that works with it.
4 — I didn’t see anyone use it for the entire three day weekend I stayed at the hotel.

This highlights a potential pitfall in the future EV charging network. Products need to be compatible, and no matter who wrote the spec, they’re not a standard if they don’t work with the product that has > 50% of the EV market share. Fortunately there was a Tesla supercharger station twenty minutes away, and it was right next to a BW3 — so crisis avoided!

Slow Charging

The other gap I’ve seen is the charging rate for some of the existing non-Tesla stations. I’ve had stations fill at less than 10 miles/hour of charging time, and most do only 20 miles/hour. That works if I am in an office all day, and have ten hours to charge, but for a shorter stop, it’s not effective.

Charging stations are an investment, so potentially there’s a business model similar to that of traditional gas stations that can see this as a service. Consumers will need to factor this into their purchasing decisions as the ROI calculators that I’ve seen assumes retail prices of electricity (i.e. $0.10 kWh) and not something with a huge markup to recover the costs of the charging equipment.


The EV market saw record numbers in 2017, a 45% increase over 2016, and in absolute terms 100k new vehicles in the US. That number may increase massively in 2018 as deliveries for the new Tesla Model 3 begin. Some estimates believe that Tesla may deliver 150k of them in the next year.

As an EV owner, I’m going to be very focused on how the distribution network keeps up, and if there are any changes to the charging technology used by them. Will the future be open standards, with chargers compatible for all, or is it really a closed platform to be dominated by Tesla and other EV makers?

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