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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41 thoughts on “Common Electricity Questions for the C-Max Energi

  1. I haven’t heard of that. A J1772 240V charger at Home Depot is $300 more. The Ford charger that I’m aware of is about $1000 more. If you find out about a $500 charger that is Level 2, please let me know.

  2. The estimated power you listed to charge the car (8.5kWh) is an over-estimate. The battery may be 7.6kWh and the charger may indeed be about 90% efficient, but the engineers at Ford would never allow the battery to get down to zero charge. In fact, doing so with a lithium battery would turn it into a brick. To ensure that the battery is safely padded, they probably don’t let it go below 20% (even though it will say it goes lower). From my brief experience so far (a few days of charging), it looks like it draws a little more than 1kW for about 6-6.5 hours.

    • It is an over-estimate. Ford uses 6.5 kWh for EV and 1.1 kWh for HEV. I haven’t found a reference for how far they let the battery discharge. I haven’t seen documentation supporting more than 80% discharge would turn it into a “brick”. If you find more than comments on forums, please let me know.

  3. Stop inaccurately using the term “charger”. In almost every case where you use the word “charger”, you actually mean EVSE. In J1772 L1 and L2 AC charging, the charger is on-board the car. See diagram at (ignore the DC quick charging part, that’s for the optional CHAdeMO port on the Leaf).

    As I posted elsewhere (this is more generally applying to EVs and PHEVs):
    “Calling them the right thing is important because there can be serious confusion re: charge rate and hardware (e.g. if you buy and install the wrong EVSE, wasting money OR you wanted a higher charging rate and got a lower max input/output OBC, which can’t be upgraded or bought the wrong EV/PHEV). There are a bunch of limiting factors to charge rate like max output of EVSE, line voltage, max output and input of the car’s on-board charger, etc.

    The ’11 and ’12 Leaf only had a 3.3 kW on-board charger (same deal w/the current Volt and Spark EV), while cars in that era of those Leafs like the Focus Electric and Fit EV had 6+ kW on-board chargers. The Rav4 EV has 10 kW OBC, like the Model S does standard. The Model S can be equipped with a 2nd 10 kW OBC (look under under High Power Home Charging). Notice they refer to:
    Second 10 kW onboard charger
    High power wall connector

    With the ’13 Leaf, a 6 kW OBC is optional (standard on the SV and SL trims while optional on the cheapest trim, the S), POTENTIALLY increasing the charge speed at 200+ volt AC charging. See

    The Aerovironment EVSE (both Nissan branded and non) at which has been sold since the ’11 Leaf has a max output of 30 amps but a 3.3 kW OBC car will only pull 16 amps @ 240 volts, at max (if memory serves). A 6.x kW OBC car will pull somewhere between 25 and 30 amps at 240 volts.

    If you buy an EVSE that can output only 20 amps (e.g. Clipper Creek LCS-25), you will not be charging a Leaf or other vehicle w/6+ kW OBC at full speeds.

    The $450 Bosch unit cited at only has a 16 amp output at max for the cheapest version. This will make no difference for a 3.3 kW OBC car (e.g. Spark EV, Volt, Plug-in Prius (possibly only 2.x kW OBC), ’11 or ’12 Leaf, ’13 Leaf S w/o optional 6 kW OBC, etc.) but will if you have a higher wattage OBC.

    To take full advantage of a 10 kW OBC car (e.g. Model S or Rav4 EV), the EVSE must support 40 amps at 240 volts (see, for example).”

    Some details about J1772 standard at

    An L1 and L2 EVSE has no knowledge of the battery’s voltage, state of charge, temperature, cell voltages, etc. It also performs no conversion of AC to DC nor does it alter the line voltage.

    • I just discovered that your post was in “pending” yesterday. I realize that EVSE is technically correct, but charger is frequently used by manufacturers, retailers, and potential customers. I don’t see that using EVSE clarifies this. The text of this article makes the distinction that you’re concerned about at least somewhat clear. However, based on your advice, I have made some changes to the article.

    • I don’t have the 240 unit.I use the one that came with the car. I live in new york the outside temp.Only givgives me about 13 miles of a charge. Am I doing something wrong.I will up grade to the 240.when I get some extra money

      • A Level 2 J1772 EVSE (“240″) will not increase your distance traveled. Your distance of 13 miles is probably because of a cold battery and use of the heater. We’ve driven the Ford C-MAX Energi and Nissan Leaf through winters in Utah. In winter, the mileage you get will be significantly less.

    • For the C-Max Energi, they will charge at the same rate because the Energi is limited to 3.3 kW. If you get a plug-in that is capable of faster charging, e.g., 6.6 kW Ford Focus or 2013 Nissan Leaf, the 30 Amp Level 2 EVSE will charge faster.

  4. Quick question :
    We have the opp to charge in a garage from a 120v outlet. Any suggestions on how to secure the charger while its charging in a public place? Its an expensive piece of equipment and chances of theft in a public unsecured setting can be very high.

    IF we do use an extension cord, where and how should we place the charger

    • With the 120v charger that comes with the Nissan Leaf you can put a paddle lock on the latch so it cannot be removed from the car. The Ford charger doesn’t have this simple feature. I don’t have a suggestion. It may be possible to drill a hole in the Ford charger’s latch. An extension cord isn’t recommended. You’re on your own if you decide to use one.

      • So, here in North Carolina we do not have a garage. We did use a heavy duty extension cord with the charger that came with the car. After nearly daily/nightly charging for 20 months, in January I had to unplug mid-charge. The extension/plug end was so hot that the prong end melted and the ground pin fell out of the cord. I don’t suppose there is anyway that the charger is under warranty from Ford. My dad (who actually owns the car) thinks this might be a good line to pursue, however, I am leaning towards that as a fruitless effort.

        Basically we never got around to running a 220 line out to the driveway. And buying a more permanent charger.

        I am missing my electric miles!

        • It’s interesting that you used it without overheating so many times before. You can always ask your dealer if it’s covered by the warranty. You can buy chargers that are far less expensive than the Ford. If you use an extension cord, you better make sure the gauge and length of the cord can handle the current draw of the charger in the future. You probably don’t want to start a fire!

    • I have found this depends on whether the climate control is on or off. If you turn off the climate control before turning off the car, you will probably see it shows 20-22 miles ( of course as soon as you turn it back on it will drop – climate control is costly!)

        • If toggling the climate control on and off doesn’t change the estimated range, it seems very strange to me. Jeff is correct that a number of about 14 is quite typical when climate control is on and the battery is charged fully.

    • Its just like any other Plug-In/EV, the EV Range is Dynamic to the driving style and temp conditions. IT will adjust over the course of your driving techniques and style to perform better than the 14 visible miles. In my VOLT ill get 46miles range displayed in summer and 25 in winter. Sometimes it shows 25 and stays there for a while…and I return on my computer over 30miles EV range.

      • I have noticed on my C max energi that over the last few days when I plug in overnight in the morning I show a battery with 41 miles range! When I drive it does feel like the range on these days is more but not twice my normal 21 miles. Any thoughts?

        • The vehicle makes a poor prediction based on a recent trip (or trips) that used little energy. I know I’ve seen 38-39 miles many times. I don’t recall seeing 41 on our C-Max Energi, but I don’t recall for sure what the highest number is. It doesn’t mean much. It could be a fun challenge to see how high the “predicted EV” range could be pushed with a long downhill descent (or multiple descents).

  5. What about charging frequency? For example, if I go on a five mile trip and return home and then want to drive 60 miles, is it okay to recharge after a short trip or does the battery need to be depleted before recharging again?

    • My practice is to connect the charger whenever we return home, on the Nissan Leaf and Ford C-Max Energi, regardless of how much the battery is discharged. I cannot find anything in the C-Max Energi manual on this subject. However, here’s an article that could imply there is a memory effect for lithium-ion batteries, including those used in EV and PHEVs: Also, keep in mind that your battery has at least an 8-year 100,000-mile warranty, and up to 150,000-mile warranty in some states.

  6. This reminds me a lot of the Organic Transit ELF Solar charged electric motorized/human powered hybrid Velomobile.Their philosopy is related too as short to medium distances can be solar powere (not the same though).

    • It does look interesting. You get portability which will be advantageous for some. Personally, I prefer the higher amperage EVSE to better support future vehicles.

    • I find it depends on the outside temperature and the climate control. If outside it is moderate (60-70) and the climate control is off during the whole drive, I get 20-22 miles. Otherwise it is less. Myfordmobile will tell you if you are fully charged or not.

    • Yes. This isn’t a problem. Here’s what the Wiki states on the J1772 standard, that the C-Max Energi uses: The J1772 standard includes several levels of shock protection, ensuring the safety of charging even in wet conditions. Physically, the connection pins are isolated on the interior of the connector when mated, ensuring no physical access to those pins. When not mated, J1772 connectors have no voltage at the pins, and charging power does not flow until commanded by the vehicle.

  7. Does the Siemens VC30GRYU Versicharge 30-Amp Electric Vehicle Charger with Flexible Indoor/Outdoor and 20-Feet Cord work with the 2014 Ford C-Max Energi?

  8. I installed the Siemens VC30GRYU Versicharge 30-Amp EVSE for my 2014 C-Max Energi. Should I set the kWh to its max of 7.2 or cut that to 3.5 kWh? Can the C-max handle the 7.2? Does it cost me more to run at 7.2 vs. 3.5? Does it matter?

    • It doesn’t matter. The C-Max Energi is limited by the electronics within the vehicle. It would charge at the same rate for either setting.

  9. Again, thanks. Approximately how many kW are used to charge a fully empty battery? I am trying to determine how to reimburse my employer when I plug in. Thanks?

    • Roughly 8 kWh is what I measured with the Level 1 (see above). A level 2 J1772 would be less, a little less than 7kWh.

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