Range Confidence: Charge Fast, Drive Far, with your Electric Car

By David Herron

Last Update: April 20, 2019

Electric cars are meant to be driven anywhere we want to go. But, currently, a combination of charging speed and the public charging network limits where electric car owners are willing to drive. Electric car charging infrastructure is not as evenly installed as gasoline car refueling infrastructure. How, then, does an electric car owner drive into an area that with little-or-no charging infrastructure?

As we see elsewhere in this book, electric cars are designed to be recharged at charging stations, and can only be charged through a charging plug. Therefore, if no charging stations are available, then the electric car will eventually run out of power and get stuck. Gasoline cars are no different because they will be just as stuck if they run out of gasoline and there are no gas stations.

The fear is if there are no charging plugs available you'll be stuck out of energy.

The truth is you can drive anywhere there are power outlets - you can drive into areas with no electric car charging stations - given you carry a portable charging station and sufficient adapters for the power outlets you’ll find. You’re not limited to official charging stations, because with the right adapter any power outlet will do.

Those of us wanting to completely divorce ourselves from gasoline face this question - How do we avoid being limited in where we can drive? How do we drive our electric car in areas with no charging stations? How can we charge our electric car from a regular power outlet? With a long-range electric car, do we need to worry over areas with no charging stations?

Some keys to driving an electric car to any location are:

  • Carry a portable charging station and a variety of power adapters.
  • Know how to properly adjust the charging rate for the outlet being used.
  • Know where to find power outlets.
  • Get an electric car with the longest driving range you can afford.
  • Plus-points for an electric car with charging flexibility.

See How and where to charge electric cars in public

Charging an electric car from a regular power outlet

The automakers in their infinite wisdom decided electric car charging must be done with a special-purpose charging cord. We cannot take a regular extension cord, plug it into a regular power outlet, and plug that directly into the car. The extension cord must be adapted to the charging port on our car.

As we noted elsewhere the single phase AC charging port uses the J1772 protocol, with one of two plug types: Types of electric car charging connectors, and compatibility: A Field Guide to electric vehicle service equipment

The key to charging from a regular power outlet is to carry a charging station in the car. Every electric car is sold with a low power charging station that's meant to be a fallback in case you get stuck somewhere. It is compact and light enough to always be carried in the car. Even though its charging rate is very low, it's better than being completely unable to recharge at all.

By carrying a charging station in the car you have the freedom to charge at any compatible power outlet. You can use the line-cord charger that came with the car, or buy a higher power charger that can be used if you find a high-power outlet.

The requirement for adjustable charging rate

If your portable charging station draws more power the power outlet supports -- say, a 32 amp charging station connected to a 20 amp (16 amp continuous) power outlet -- well, you'd better hope the circuit breaker or fuse does its job. It's important that the charging rate be within the limits of the wiring and power outlet you're using. An electrical fire is possible if you make a mistake.

Some possible methods to adjust the charging rate:

  • The J1772 protocol automatically adjusts the charging rate, but this requires that the charging station know the limits of the power outlet it is connected to.
  • Some electric cars support changing the charging rate from settings on the dashboard, but not all.
  • Very few EVSE's allow the user to change the charging rate.
  • The OpenEVSE and GoPlug chargers let the user change the charging rate by pressing buttons to enter the setup mode.
  • The Tesla universal mobile connector has adapter plugs that automatically inform the charging station what plug is being used, and it can limit the charging rate.

I own an OpenEVSE, a very portable charging station you build as a kit. By pressing the setup button you can change the charging rate from 6 amps up to (I think) 40 amps. Once selected, the OpenEVSE overrides the charging rate requested by the car, so your charging session fits within the constraints.

For example, one place I frequent has several NEMA L6-20 plugs available. These are 240 volt outlets and the charging session must be limited to 16 amps. A quick adjustment on the OpenEVSE takes care of that.

See Electric car charging within electrical code and power outlet limits

Driving into no-charging-station-land

Some areas still have signs warning "Last gas for N miles" because there's no gasoline stations. Those signs do get ignored from time to time, and people get stuck with no fuel. That nearly happened to me the last time I drove across the Mojave Desert, not because I ignored the warning signs, but because of the distance between gasoline stations that were still in business.

The problem is not unique to electric car owners. But, where a gasoline car owner might carry an extra fuel tank, it's not practical to do that with an electric car because of the size/weight required.

On the other hand, if that area has electricity it's possible to charge the electric car --- if you bring along a charging station, and have the right adapter cables. The outline is:

  • Plan ahead carefully, making sure you know what kind of power outlet is available. The Plugshare application lists places known to make their power outlets available to EV drivers.
  • RV parks often have high power outlets meant to be used by RV's and can easily be used by an EVSE
  • Carry a charging station that's both compact and high power
  • Bring any extension cords required to reach from the power outlet to where the car will park
  • Bring any adapter cables to match the power outlet to the plug on your charging station
  • Plan the travel time knowing you'll be stopping to charge

For some details see these other pages

Using a portable generator to recharge

Another pragmatic option is to carry a portable genset and a gasoline tank. As long as the gasoline supply holds out, the genset will generate electricity you can use to charge the car.

To power a 6+ kiloWatt charging station, the genset should have a larger capacity, perhaps 8 kiloWatts.

Clearly there will be a way to calculate the kiloWatt-hours that can be generated from the gallons of gasoline you can carry. That, along with knowledge of your car's energy efficiency, will give you an estimate of the driving range.

Portable solar array?

Yes you can do this, but it'll be bulky. For example a few have designed trailers with fold-out tilting solar arrays that they deploy at any stop.

Can a long-range electric car ignore charging station gaps?

Long-range electric cars currently have 300-350 miles range, or about the same as a gasoline car. Gasoline car drivers do get stuck out of fuel from time-to-time even with their range advantage. Therefore, an electric car driver is also vulnerable.

Even the much-vaunted Tesla Supercharger network has gaps large enough that a 100+ kiloWatt-hour Tesla would have trouble.

In Solving range anxiety in daily driving - putting range confidence into practice we showed how a 200+ mile range electric car can take a long distance trip through the Midwestern US with its relatively low density of charging stations. Clearly, it's more possible for a longer range electric car to cross a long gap with no charging coverage. It will require careful planning, of course.

A shorter range electric car can take such trips with extra careful planning, as long as the driver is comfortable with making do with regular power outlets.

Bottom line is the electric car drivers must currently make careful plans when taking a long-range trip or into areas with no charging stations.


On one trip I had traveled by airplane to Florida, and on a lark rented a Nissan Leaf because it was available at a good price. In 2012 the charging network was nowhere as developed as it is today. I needed to drive between the outskirts of Tampa, where our hotel was, and Daytona Beach, and to do daily round-trips on Saturday and Sunday. We stopped at a shopping mall on the way to the hotel and charged there for awhile. And PlugShare showed a couple charging stations in-between. The key to success that weekend was the 120 volt power outlet made available to me at the hotel, and another made available in the Daytona Speedway paddock. I tried using ChargePoint but of course had left my membership card at home. A Nissan dealer's charging station proved to be handy while having dinner at the shopping mall next door.

That trip would have been a failure if I'd not wangled permission from the hotel and the race track to use power outlets, and if I did not have the line cord charger. Even a lowly 120 volt power outlet can be incredibly useful.

Another example comes from the travels of Terry Hershner. He is an avid electric motorcycle rider who specializes in long distance travel on electric motorcycles. Since 2012 he's undertaken several cross-country trips on electric motorcycles, including lots of places with no charging station support. On trips he carries a variety of adapter cords on his bike. The common place to charge is campgrounds, since they often have NEMA 14-50 outlets that will be used by RV owners. He has also used 14-50 outlets at laundromats, and at machine shops.

Range Confidence is Copyright © 2016-17 by David Herron

About the Author(s)

David Herron : David Herron is a writer and software engineer focusing on the wise use of technology. He is especially interested in clean energy technologies like solar power, wind power, and electric cars. David worked for nearly 30 years in Silicon Valley on software ranging from electronic mail systems, to video streaming, to the Java programming language, and has published several books on Node.js programming and electric vehicles.
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