Faster Charging a Major Advantage for Ford EV
Ford's biggest selling point for its 2012 Focus Electric ($39,600) is that it charges twice as fast as other electric vehicles when using a Level 2 240-volt supply. Having tested a Focus Electric for a couple of days, I can confirm that the claim is both true and a compelling advantage indeed.
In the simplest terms, a depleted Focus battery can be fully recharged in about four hours compared with about eight hours for a Nissan Leaf. The Mitsubishi i-MiEV, which I recently reviewed, uses a smaller battery and takes closer to seven hours. But it's not just about full charges; it's about how many miles you can drive in a given day, and some other less obvious advantages.
For the record, the Leaf and i-MiEV offer optional ports for DC quick charging, known as Level 3, which the Focus doesn't support. (Ford says it's waiting for a standardized connector.) But Level 2 is what matters most because Level 3 charging would be cost prohibitive for the home, and no car that relies solely on battery power is viable if all you have is 120-volt household power, known as Level 1.
How does the Focus Electric charge faster than its competitors? It's pretty simple, really: Its onboard charger has a capacity of 6.6 kilowatts. All the other EVs, and the Chevrolet Volt, are limited to 3.3 kW.
To define terms, a "charger" isn't what you probably think. The thing with a cord you install on a wall or find on a post in a public setting isn't the charger; it's the electric vehicle supply equipment, or EVSE. Nissan calls it a "dock." Technically, the charger is aboard each vehicle. It converts AC power to DC and manages the battery pack's charging process.
Before I get into the reasons behind all of this, here are some of the less obvious advantages I observed in two days with the Focus Electric:
- Faster cabin conditioning: When I remotely preheated the Focus Electric, it drew more than 5 kW from the EVSE, meaning it was warming the cabin more quickly. (Conditioning the cabin before you unplug and drive preserves range.) We know that our Leaf's cabin heater can use 4.5 kW or more when driving, yet we've witnessed that it's limited by its own 3.3-kW charging rate when plugged in.
- More miles per day: This is the simplest calculation of all. If you're adding twice the range of another EV over the same charging period, you can get more miles out of your car in a day's time. Sometimes I'll come home with our Leaf and then need to take another car out for the evening while the Leaf recharges. With the Focus, a few hours of charging were enough to give me the range I needed to take it out again.
- Charging at a higher rate while you're shopping makes more sense: Walgreens is one of the most aggressive adopters of Level 2 charging, but we question if plugging in a Leaf for a 10-minute stop is worth the effort, even if it's free. But a Focus might be a different story.
- Fewer dollars per mile: Most charging happens overnight when electricity costs less, but for the sake of argument, faster charging means you're better able to exploit off-peak rates when they're available. A Focus could finish charging while another EV might linger into the higher-rate period.
- More miles per dollar (or $2): A big reason to buy an EV is for cheap home charging, but you may have the opportunity to charge publicly. Most public Level 2 charging remains free, but when you're billed, it's typically by time rather than the amount of electricity used (a legal issue that's still being sorted out). So if you add 20 to 30 miles of range for every hour of charging, you're getting more for your money than a Leaf owner, who adds 10 to 15 miles in the same period.
With all these advantages, why don't the other EV makers have 6.6-kW charging? They say it's an issue of size and cost, though Nissan has announced that the 2013 Leaf will support 6.6 kW. What's frustrating is that, for the most part, the onboard charger is the sole bottleneck.
However, not all Level 2 EVSEs can charge at the higher rate. Level 2 charging is standardized and requires 240 volts, but to deliver 6.6 kW to the car, you need two things: an EVSE that can supply that much, and enough current going into it. (A notable mass-market exception is the Voltec-branded Level 2 EVSE Chevrolet sells as an option for the Volt.)
Our SPX Power Xpress EVSE has been flawless when charging a Leaf, Volt and i-MiEV, typically drawing about 3.4 kW. When I charged the Focus Electric, it drew 5.6 kW rather than the full 6.6 kW. Unfortunately I wasn't aware of a hidden setting on our EVSE intended for use with a 30-amp circuit, even though I had 40 amps. My mistake. This limited its output to a possible 5.7 kW versus 7.7 kW.
Even at this level, the depleted Focus Electric battery charged in four hours and 10 minutes. With the correct setting, the car would have broken four hours easily, and this is what's frustrating about the charging rate among other EVs. It typically takes eight hours to charge our long-term Leaf with this setup.
Both our existing EVSE and the networked ChargePoint unit in our parking garage — which delivered more than 6 kW when we plugged it into the Focus — have been ready for this charging rate for more than a year. The same is true of the AeroVironment EVSE purveyed by Nissan and Mitsubishi as well as the Leviton device Ford has selected. The cars themselves have been the limiting factor, until the Focus Electric came along.