Common Electricity Questions for the C-Max Energi

What’s the difference between a charger, charge station and EVSE?  The Ford C-Max Energi uses a J1772 compatible charge station, also called an EVSE, which means “electric vehicle service equipment.”  The electrical components involved in charging the Energi are located in the car and the charge station.  Although the electronics that convert the AC of the house to the DC used by the Energi is located in the vehicle, it is common to refer to the EVSE or charge station as the charger.

What’s the difference between Level 1 and Level 2 chargers?  The Level 2 chargers are faster.  There are two types of chargers for the C-Max Energi, AC Level 1 and 2 both with the same J1772 connector.  A Level 1 charger is supplied with the C-Max Energi.  A Level 2 charger can be purchased and installed in your home.  Level 2 chargers are often available in public locations for free.  A Level 2 charger will charge about three times faster for a C-Max Energi.  According to various posts, the Level 2 chargers are somewhat more efficient, about 80% compared to 72% for the Ford Level 1 charger[The SAE International charging configurations and ratings terminology sheet is here.]

I’ve tried faster J1772 Level 1 and Level 2 chargers, but the C-Max Energi doesn’t charge any faster.  Why?  Because charging equipment is inside and outside of the C-Max Energi.  I haven’t been able to find specifications for the on-board charging regulator for the C-Max, but based on charging times of 7 hours at 120V and 2.5 hours at 240V, it appears as though the Energi is limited to 1.4 kW for Level 1 and 3.3 kW for Level 2 chargers.  It won’t speed charging times for a Level 1 or Level 2 charger with faster kW specifications.  Level 1 AC chargers use the standard AC 120V receptacle and can operate at 1.4 kW drawing up to 12 amps of current and 1.9 kW drawing up to 16 amps.  Level 2 AC chargers use standard AC 240 V split phase and can operate at 3.3 kW, 7.2 kW and 19.2 kW drawing up to 80 amps for the 19.2 kW 2009 specification.

How much electricity is required to charge a C-Max Energi? About 8 kWh for a full charge with the Ford 120V Level 1 charge station supplied with the C-Max Energi.  This is based on measured full charges with our Energi using a Kill-A-Watt meter.

How efficient is the Ford 120V Level 1 charge station?  72%.  Tom in San Diego posted in the Fordcmaxenergiforum results of testing the efficiency of the Ford 120 Volt charge station that comes with the Energi.  It is only 72% efficient (see the graph below).

Ford 120V Charge Station Efficiency

Ford 120V Charge Station Efficiency

How much does this electricity cost?  Electricity costs vary widely.  There could be a discounted price for charging at night.  At my home (which is typical), the cost is 12 cents per kWh.  The cost to fully charge the battery would be about one dollar.

Are there public charging locations?  What do they cost?  There are more than 10,000 public charging locations in the U.S.  About 85 percent of the public chargers are free.  There are different ways to find charger locations.  (As of August 2013, free chargers are less common.  In Utah, Walgreens has started charging $2.50 per hour, which would make the electricity more expensive than refueling with gasoline and less convenient.)

How much does it cost to drive with electricity rather than gasoline?  It depends on your cost for electricity at home and how often you use free public chargers.  Using 12 cents per kWh you can drive about 24 miles in the city for one dollar.  Assuming you drive 20 city miles each day on electricity and you pay 12 cents per kWh, your annual cost for electricity will be about $410.  According to the EPA, the C-Max Energi has ratings of 108 MPGe city, 92 MPGe highway, and 100 MPGe combined.  The EPA uses 33.7 kWh per gallon-equivalent to calculate the MPGe.  The corresponding miles per kWh would be 3.20 city, 2.73 highway, and 2.97 miles/kWh combined.  The cost of a kWh is typically 12 cents.  Assuming 72 percent efficiency when charging, for one dollar a C-Max Energi could be driven 19.2 miles city, 16.4 miles highway, and 17.8 miles combined.  [The calculation is ((108/33.7)/.12)*.72 for the city.]  As with gasoline, how you drive will affect your cost.  The EPA states the 2012 Nissan Leaf gets miles per kWh of 3.15 city, 2.73 highway, and 2.94 combined.  My personal experience with a Nissan Leaf is better.  My average is 4.1 miles per kWh after driving more than 8,000 miles in a Nissan Leaf.

Ford C-Max Energi Charge Port

Ford C-Max Energi Charge Port with Nissan Leaf J1772 Charger

What is the range of the C-Max Energi when driving with electric energy only?  When C-Max Energi is put in EV Now mode, it uses only electric energy (EV).  According to the EPA, the electric energy range for the Energi is 21 miles.  According to a Forum post by Tom in San Diego, 21 miles is consistent with his experience (see the graph below).  The distance you drive with electric energy will be dependent on how and where you drive.

Ford C-Max Energi EV Range

Ford C-Max Energi EV Range

Do I need to use the charger that comes with the C-Max Energi to charge it?  No.  Any 120V AC Level 1 or 240V AC Level 2 charger with the J1772 connector will charge the C-Max Energi.  The Tesla and Nissan fast chargers are not compatible with the J1772 standard or the C-Max Energi.

How long does it take to charge the C-Max Energi?  According to Ford, it takes 7 hours with the 120V AC Level 1 trickle charger that is supplied with the C-Max and 2.5 hours with a 240V AC Level 2 charger.  Based on full charges with our Energi, it takes 6 hours with the 120V AC Level 1 charger.  Based on full charges with our Energi, it takes just over 2 hours with a 240V AC Level 2 charger.  These times assume the battery is fully discharged.  It probably isn’t.

Are there any special requirements for a charger?  The 120V AC outlet that you plug your Level 1 trickle charger into should be on a dedicated 15-20 amp circuit.

Ford Level 2 J1772 Charger

Ford Level 2 J1772 Charger


What does it cost to upgrade to a Level 2 charger in my garage?  The cost depends on the charger you select and the cost of installation.  Installation costs vary from a couple hundred dollars to thousands of dollars, depending on your home.  Although any J1772 charge station will charge the current C-Max Energi at its fastest possible rate, it may make sense to install a 30 amp charger to support future vehicles.  The increased cost is not that significant.  It is also important to make sure that the cord is sufficiently long to satisfy current and future vehicles.  There are a few good choices.  ClipperCreek now has the HCS-40.  This 30 amp EVSE with a 25 ft cord sells for $590.    Bosch has the 30 amp PowerMax EVSE with an 18 ft cord priced at $593.  Another good alternative is the Schneider Electric EV Link 30 amp at Home Depot for $599 with an 18 ft cord.  If you decide to install a 240V Level 2 charger, it makes sense to have an electrician install a 240V outlet in the garage on a dedicated line.  That makes it possible to move the charger to another location.  The tax credit for installing a charge station expired on December 31, 2013.

Where is the 120 volt charger stored in the C-Max Energi?

C-Max Energi Charge Port Storage

C-Max Energi Charge Port Storage is Behind Driver’s Seat

There is a compartment in the floor behind the driver’s seat for storing the charger.

When I’m done charging, can I just pull the charger from the 120V outlet?  No. Do not pull the charger’s wall plug from the outlet while the vehicle is charging. This can damage the cord or outlet.  Disconnect the J1772 connector from the C-Max Energi first.

Are there concerns about the high voltage of the C-Max if I’m involved in an accident?  Yes.  A short blog was published on this, “Emergency Response for The Ford C-Max.”  The C-Max High Voltage disconnect is located behind the rear passenger side seat.

C-Max High Voltage Disconnect

C-Max High Voltage Disconnect is Located Behind the Rear Passenger Side Seat

Are there two batteries for the Ford C-Max Energi, for “hybrid” and “plug-in” operation?  No.  However, from the user perspective there appears to be two.  The software for the drivetrain divides the battery into a 1.1 kWh “hybrid” battery and a 6.5 kWh “plug-in” battery according to an article in Automotive Engineering Online.  As far as I can tell, Ford never charges the battery to 100% or discharges it to 0% to prolong battery life.  A full charge of the Energi adds about 5.5 kWh of charge to the battery and requires about 8 kWh from the wall (electric meter).  When the potential energy is high (at the top of a hill, canyon or mountain) and a long descent is encountered, after the “hybrid” battery is fully charged the “plug-in” battery will start charging.  As a test, I drove up American Fork Canyon until the “hybrid” and “plug-in” batteries were completely discharged and the ICE (internal combustion engine) started.  I then turned around and descended to the starting point.  The hybrid battery was fully charged and the “plug-in” battery had a 30% charge after returning to the start.

This blog was first published December 28, 2012.  It was updated January 5th, 16th, 19th, March 2nd, August 27th, September 11th, 2013 and January 20th, 2014.



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Arches and Canyonlands National Parks on Less Than One Tank

Ford C-Max Energi near Courthouse Towers

Ford C-Max Energi near Courthouse Towers in Arches National Park

My first road trip was a four-day Labor Day Weekend trip to Arches and Canyonlands National Parks.  I’ve been putting a lot of “hybrid” miles on our new Ford C-Max Energi.  I haven’t been driving fast (almost always 65 MPH or slower).  I try to travel as far as possible on EV when the electric motor is efficient.  When ascending elevation, I use the ICE (internal combustion engine) and then let off the accelerator as soon as possible near the crest of the hill and run in EV.  I’ve also used the pulse and glide technique, using the ICE to gain speed somewhat faster than necessary, let off the accelerator a couple MPH and then let the Energi glide in EV.  Probably more than anything, I just sit back, relax, enjoy music and try not to be in a rush.

I filled the tank at a gas station close to my house on departure and return.  I started with a full charge with the C-Max Energi in EV Later mode.  I used the excess electricity when I thought the electric engine would be most efficient.  The trip was 564.2 miles according to the odometer.  The gas pump display stated I used 12.666 gallons at $44.95.  According to the C-Max Energi’s display, I used 4.1 kWh and 11.73 gallons.  The C-Max displayed my MPGe for the trip as 47.5.

I visited the Island in the Sky District of Canyonlands National Park stopping for short hikes.  My first stop was False Kiva at sunset.  It’s a classic photo location and it wasn’t a disappointment.  The sunset was spectacular.

False Kiva in Canyonlands National Park

False Kiva in Canyonlands National Park

I then spent the night taking nightscape photos at Mesa Arch.  I spent the entire night at the Arch (I slept for a hour or so without pad or bag on the slickrock, no food, camping gear, etc. – just water).  It was quite warm.  The classic photo op of Mesa Arch at sunrise was worth it too.

Mesa Arch at Sunrise

Mesa Arch at Sunrise

I spent the next three days with family in Arches National Park and the Moab area.  Every night I drove to the Windows section of Arches at night for photography.  There were a lot of other tourists and photographer’s there every night, but not as many as during the day.

North Window Arch and Milky Way

North Window Arch and The Milky Way


I love the many spectacular locations nearby on the Colorado Plateau.  Arches was quite crowded though.  One location near the Devil’s Garden Campground turned out to be a favorite without the crowds.  Broken Arch at sunrise is spectacular.

Broken Arch at Sunrise

Broken Arch at Sunrise

I’m getting to know the Energi better.  I really enjoy driving it.

$2.45 Gasoline Plus 93 Cents Electricity

I’ve had an epiphany.  It was staring at me all the time.  I need to combine my interest in electric vehicles with my love of nature, photography, and astronomy.  I have trips planned to Arches National Park, Great Basin National Park, Capitol Reef National Park, and California Sea Arches/Lava Beds National Monument within the next 30 days.  I know.  I keep busy.  Yesterday, from my house in Highland I drove through American Fork Canyon past Timpanogos Cave National Monument, along the Alpine Loop Road, onto the Cascade Springs Scenic Drive, over the gravel road to Midway, and through Provo Canyon past Bridal Veil Falls back to my home.  The 56.7 mile round-trip cost $2.45 in gasoline (at $3.60 per gallon), 93 cents for electricity (out of the wall, assuming the charger is just 72% efficient).  For less than the cost of one gallon of gasoline I took a road trip that could easily fill a day of fun outdoor activities.

Cascade Springs Loop Trip Meter

Trip meter for alpine loop trip from my house.


I’m having fun with the C-Max Energi.  I need to stop blogging and get ready for the trip to Moab.  Here’s a few photos along the way.

C-Max Energi Alpine Loop

C-Max Energi on Alpine Loop Road


C-Max Energi Cascade Scenic Drive

C-Max Energi on Cascade Scenic Drive


C-Max Energi Midway Gravel Road

C-Max Energi on gravel road to Midway Utah