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

By David Herron

Can you drive an electric car away from charging network coverage areas?

We want to drive our electric cars everywhere, just like gasoline car drivers can do. 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, driving in any area lacking charging stations raises the question of how you'll recharge the car. The fear is if there are no charging plugs available you'll be stuck out of energy.

Of course gasoline car owners have a similar problem. There are areas with no gasoline stations, and gasoline car drivers can be just as stuck without fuel as would an electric car driver. The difference is the gaps with no electric car charging are much larger than the gaps with no gasoline stations.

The truth is you can drive anywhere there are power outlets - 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.

The key is knowing where the power outlets are. Plugshare is your friend because you can set the filters to show power outlets known to be friendly to EV owners.

The second key is to carry a portable high-power charging station and make sure you can adjust the charging rate.

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?

See How do I charge away from home?

Charging an electric car from a regular power outlet

The automakers in their infinite wisdom decided recharging an electric car 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: A Field Guide to electric vehicle service equipment (EVSE's)

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. Limiting yourself to the low-power station sold with the car limits that freedom. There are a few high power compact charging stations that give you a full 6+ kiloWatt charging rate.

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.

Some electric cars support changing the charging rate from settings on the dashboard, but not all. Most EVSE's do not support changing the charge rate at the EVSE. The Tesla portable charging unit has adapter plugs informing the EVSE of the maximum charge rate, and it automatically adjusts to match.

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 6-20 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.
  • 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 Daily Driving and longer trips on electricity - 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 cars 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.


Range Confidence is Copyright © 2016-17 by David Herron

Can you drive an electric car away from charging network coverage areas?

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