Friday, May 23, 2014

Will an EV Fit Our Driving Lifestyle?

We find that in discussions with acquaintances about the subject of EV ownership that the most common reservation about ownership of the current crop of EVs offering ranges of 75 to 80 miles is, "Yes, but what if I suddenly decide to . . ."  In nearly every case, these comments have been made by individuals who have absolutely rigid daily schedules with invariable driving routes, and are the least impulsive of characters.

I, on the other hand, am known to set off on a mission with little to no notice.

And yet, after seven and a half months of EV ownership, we have yet to jump in one of our gasoline-powered vehicles because a trip exceeds the range of our Focus Electric.

To be fair, we're trying harder than most to make the EV work. To that end, we're sometimes defining our itinerary by the requirements of recharging on the road. If we were driving a hydrocarbon-fueled car, some of those trips would have been different, and a few would have taken significantly less time due to fueling (charging). We're treating this EV ownership as a learning adventure, and so it's interesting and fulfilling to go through these new experiences. But we're actually doing more exploring than we would have before owning the EV; driving more often, and further from home than we typically would, just to see how bad it is.

And you know? It's not bad at all.

Sure, once our round trip exceeds 70 miles, it takes some extra thinking (which I find fun, but many wouldn't). When it's a LOT further - approaching two full battery charges, we look for excuses to spend the hours charging doing something useful or fun in proximity to the charging site. Did we do this before owning an EV? No. But the point is that rather than Cramping Our Style, our EV has encouraged us to explore its limits. We haven't called AAA to tow us to a charging site. And we've never gotten caught out so that we end up sitting in our car waiting for enough charge to get to our next waypoint.

So what's the takeaway?

When we were deciding whether an EV would fit our lifestyle, I discovered that we'd only driven our daily driver about 5,000 miles during the previous 12 months. As it stands right now, we're on track to put about 8,000 miles on the Focus Electric every 12 months. That's how enthusiastically we've been using it.

Living in Los Angeles, round-trip distances to points of interest can certainly challenge even two full charges (160 miles) of our Focus Electric. And yet we've never resorted to another form of intra-city transport since getting an EV. 

As I've written previously, the current state of public charging infrastructure is such that it's unlikely to be truly useful to most people. But I think the 80 mile typical range of a single, daily EV charge suits the majority of drivers. For anyone with a predictable itinerary under 60 miles per day (many sources claim the average daily U.S. commute is 32 miles, and I'm allowing for impromptu side trips), the cost of operation and ease of use make an EV a perfectly serviceable second car (we actually think of our EV as our primary vehicle, and our small motorhome as a secondary vehicle for even short- and medium-distance adventures).

Thursday, May 22, 2014

Avoid Automatic Temperature Control to Minimize Range Impact from Air Conditioning in a Ford Focus Electric

It’s now May 2014, and we’re entering our 7th month of leasing a 2013 Ford Focus Electric. Here in Southern California, we’re having a hot spell, with temps touching 100 degrees, and thus we enter a new phase of our experiment that is EV Ownership: hot weather operation.

Not having an internal combustion engine (ICE) from which to utilize waste heat, the Ford Focus Electric (FFE) uses power from its main 325 volt, 23 kilowatt-hour lithium-ion propulsion battery to power what is obviously some kind of electrical resistance heater, probably not unlike the glowing wires in your toaster or hair dryer. Based upon my observations and crude calculations (using data from the FFE’s own range-estimating battery gauge), the heater uses electricity at a rate of around 6,000 watts - about the same as the typical household electric oven, and what I'm guessing the FFE requires to move through the air at 30 mph. This has a devastating impact upon vehicle range. The FFE has a nominal range of 80 miles or so (potentially going over 120 miles in low-speed, stop-and-go traffic, or only 60-65 miles at 65 mph on a hilly road). If the heater were powered for the duration of a full-battery trip, its total range would be reduced by about 30% - dropping the range from 80 miles to around 56. Yikes.

I’m sure we’re not the only EV users who choose to wear warm clothes and make do with our seat heaters whenever possible. We live in Los Angeles, and our mild local weather played a part in our decision to take the EV plunge. I probably wouldn’t have "gone electric" if we lived in the FFE’s home state of Michigan. Between low-temperature battery efficiency loss and having no choice but to run the heater, I wouldn’t be surprised to lose half of the Focus’ range in truly cold climes. But SoCal winters rarely reach the 30s, so that’s not an issue.
In my early experiments with the FFE’s HVAC (Heating, Ventilation and Air Conditioning) system, I was as struck by the apparently small range impact of the A/C system as I was by the traumatically high burden of heating the cabin. This is particularly impressive, since the FFE has an electrically-powered refrigerant compressor, and because A/C compressor load has historically been a significant contributor to energy use, even in conventionally-powered automobiles. (Since writing this, I’ve read that electric A/C compressors are a trend in automobiles in general, so they apparently provide some efficiency benefits.) Furthermore, the Focus Electric’s A/C system is fairly effective, maintaining a comfortable cabin even during an hour of 100 degree driving, despite bright California sunshine and the FFE’s generous greenhouse.

Doing experiments today in 98 degree weather, I observed a 10.7% reduction in estimated range by engaging the A/C and selecting “LO” temperature (the HVAC system never stops cooling at this setting). But as I raised the target temperature on the HVAC system until it exceeded what was the apparently the cabin's current temperature (at 71° F), the battery range dropped precipitously (see graphic below), reducing range by over 26%. Obviously, the system was engaging its electric heater to modulate the HVAC temperature.

In an internal-combustion vehicle, with its vast supply of free waste heat, mixing in warm air with dry, refrigerated air to adjust temperature is a practical approach (though running a compressor full-time does impact fuel use and vehicle emissions). But in the range-challenged world of BEVs (Battery Electric Vehicles), it is decidedly NOT practical.

I appreciate that the Focus Electric is a “conversion” of sorts - that is, it’s not a ground-up design of a vehicle intended to run on electric propulsion alone. Ford obviously makes and sells only enough of these to fulfill federal mandates or incentives (only a few thousand have been produced in two years), and their decision to engineer a BEV based upon their successful and mature Focus platform is sound (Ford proudly mentions that Focus Electrics are built amongst their fossil fuel-burning siblings on the same production lines in Wayne, Michigan). I accept that like some of the other adaptations of existing platforms, there are compromises that manufacturers and users have to accept: the cargo area is severely diminished by battery pack; just maintaining a fog-free windshield costs 30% of the vehicle’s range; and vehicle dynamics reveal that Ford didn’t engineer the Focus Electric’s suspension for that added 600-odd pounds of battery.
(I’m a harsh critic of any product in general, and automobiles is a lifelong hobby, so I’m particularly picky about vehicle design and performance. But though I sound negative, the Ford Focus Electric is generally a dandy car, and we enjoy using it daily.)
But having the energy-sapping 6 kW heater turn on in a BEV when it’s 100 degrees outside is absurd. Perhaps there’s some reason they don’t want to cycle the electric refrigerant compressor off and on, as conventional auto A/C compressors did for decades. Perhaps the sensibility of the designers is to always provide low-humidity cabin air, regardless of outside temperatures. Many contemporary automobiles run their A/C compressors full-time, mechanically routing some or all of the dehumidified “conditioned” air through the engine-coolant heater core as necessary to supply the cabin with desired air temperatures. But this is an electric car, and it’s already a hard sell to convince the public to buy automobiles with 1/4 of the range of their existing vehicle, and which takes hours instead of minutes to refuel. Further crippling the range of the vehicle in hot weather (and most chemical batteries neither like being hot nor cold) because the heater is employed to counter the A/C system's cooling - that’s just asinine. And although the gas-engined Focuses probably use warm-air blending in their HVAC systems - and the FFE has no doubt inherited much of that system - Ford probably had to design and manufacture an electric heater which surely didn’t exist in the conventional Focus. So they must have had the opportunity to configure the control systems not to energize the heater when in “A/C” mode.

In the last few days, I’ve discovered that operating the Focus Electric’s air conditioning system in high-90s weather and bright sunshine results in: 1) a comfortable cabin environment; and 2) the HVAC system’s apparent inability to reduce cabin temperatures much beyond that comfortable temperature. So while it appears that the target temperature on the HVAC system can be set to a typical temperature: say, 72 or 74 degrees, with the attendant 11% range loss in 100-degree conditions - the reality is that if the outdoor temperature then drops to, say, 85 degrees, the A/C system is then able to achieve those target temps. At the point at which the target temp is achieved, the FFE turns on its heater to maintain that target, as evidenced by a sudden reduction in estimated range. So ironically, the energy consumption for cooling the cabin in the hottest weather is far lower than if the temperatures are cooler (if the HVAC system is allowed to automatically control the temperature).

My strategy for minimizing energy usage while cooling the cabin is simply never to set a target temperature. I set the HVAC target temperature to the “LO” minimum setting, and adjust the cabin temp by adjusting the fan speed, Recirculation mode and vent openings. This prevents the system from ever reaching a target temp and energizing the heater.
  • If it gets too cool:
    • Decrease HVAC fan speed
    • Re-aim the vents away from occupants
    • Close vents partially or completely
    • Turn the Recirculation mode off, so that the system uses warmer outside air
  • If it gets too warm:
    • Open vents and aim more directly at occupants
    • Increase HVAC fan speed
    • Turn Recirculation mode on, so that the system ingests pre-cooled cabin air
Manually turning the A/C mode switch off and on when the cabin feels too warm or cool, like automobile HVAC thermostats of days past, will also work. This will use the least energy short of using no refrigeration at all. But this is a very inconvenient and invasive way to operate the vehicle.
(NOTE: It’s important to also set the temperature target to “LO” when simply ventilating without running the A/C system, for the same reason. If for any reason the HVAC system measures the cabin temperature as being lower than the requested temperature - i.e., the air cools as the sun sets - it wil energize the heater. Again, in internal-combustion cars, this warming of air is essentially free. But in an EV, this shouldn’t be the automatic behavior of the HVAC system.)

I find this all more than a little disappointing. This is the first vehicle we've ever owned that had a fully "automatic" HVAC system, allowing the left and right cabin occupants to simply pick a temperature and ignore the system, which then provides comfortable temperatures by whatever means necessary. But since the system is hardly energy-efficient or well-designed for EV use, I'm unlikely to ever engage the automatic feature.

Some of the inefficiency of internal-combustion engines (ICE) results in constant waste heat emitted from the cooling radiators and exhaust pipes of those vehicles. Our Focus Electric's cost of operation is a fraction of a similar ICE vehicles, partly because its systems suffer less thermal loss. However, having to then generate cabin heat for occupant comfort and safety becomes an energy burden which must be accounted for and borne by the same economically- and dimensionally-limited electro-chemical batteries which currently constrain EV range and refueling time.

In this particular case of the Ford Focus Electric, I think a lot of improvement might be gained by minor software and hardware changes. If I could, I'd just disable the electrical heater in the summer altogether (although I think it may be involved in battery pack heating and cooling, which probably takes place year-round).

I recently read in an online forum of Focus Electric users that some anomalous behavior of the HVAC system (sometimes powering up with the blower in full blast, always turning on the A/C mode with the fan, etc.) could be remedied by rebooting the car's infamous MyFord Touch system. This suggests that perhaps the “heater with A/C” behavior about which I’m ranting here is under software (designed by Ford, and running on the Microsoft Auto operating system) control. So there’s some possibility - even hope? - that the behavior could be changed - or at least made user-optional - by a future firmware upgrade. Yeah, right.

I'd like to think that purpose-built electric vehicles might incorporate better ideas about scavenging and routing the inevitable waste heat created in the vehicle's energy and propulsion systems, keeping them in thermal reservoirs for use in cabin climate, and generating additional heat as economically as possible. In our Focus Electric, simply attempting to prevent the windshield from fogging in cold weather - a safety-related issue - requires energizing the monstrous battery-zapping heater. Ideally, there should be a very low-power defogging heater which can run constantly in these conditions.

Carrying around stored electrical energy for automobile propulsion remains a challenge in search of a solution. Although the Tesla Model S would appear to have achieved something with a claimed 300 mile range, it's 85 kilowatt-hour battery contributes substantially to its $90,000+ price (which may not be profitable) and certainly to the car's massive 4,700 pounds. And while the Model S has a range which sounds similar to a fossil-fueled car, even its proprietary, semi-exotic and rare Supercharger charging stations take 30 minutes to add 170 miles of range. Use existing public charging infrastructure to recharge your Tesla Model S, and it takes the same 20 miles/hour as most other EVs - not even remotely like a gas-station fill-up. If future battery solutions provide similar range at a fraction of the cost and half the weight and volume, having a comfortable cabin in an EV will cease to be an extravagance.

For now, you can stay as warm or as cool as you like, as long as you're not trying for maximum range.

5/26/2014: I've performed additional testing. Here are some results.

The behavior where the FFE’s HVAC system energizes the heater while in A/C mode is complex. Here are observations I have made which characterize the system’s apparently energizing the electric heater to balance cooling in order to maintain a target temperature. Notice that the results are dependent upon a combination of ambient temperature and selected HVAC target temperature:
  • First, configured the Message Center display (left of the speedometer) to display MyView, and configured MyView to display Accessory Power. With HVAC off, the Climate level displayed no power use.
    • With outdoor temperature reported as 98°F, in bright sunshine:
    • Turned on the HVAC system, and turned on the A/C (NOT using “Auto” mode).
    • Set target temperature to 73°F. 
    • MyView displayed about 1kW of power use for Climate.
    • After allowing the A/C to cool the cabin for 20 minutes of driving, only small variations in Climate power use occurred. 
      • This is apparently because when outside temperatures were very high and the vehicle was in direct sunlight, the A/C was unable to achieve the temperature.
      • Increasing the target temperature while observing the Climate power level, the power level increased to 5+kW when the target temperature was set to 78°F - apparently the current measured cabin temperature.
    • CONCLUSION: At very high outdoor temperatures, the system is incapable of cooling the cabin to what might be considered typical comfort temperatures: i.e., 72-75 degrees F. Because the system cannot achieve the selected temps, the heater is never energized to balance the refrigeration system. 
  • With outdoor temperature reported as 80°F, in bright sunshine:
    • Turned on the HVAC system, and turned on the A/C (NOT using “Auto” mode).
    • Increased the target temperature until MyView’s Climate power increased to over 5kW - in this instance, this occurred at 75°F.
    • Reduced the target temperature to 74°F at which point Climate power dropped to less than 1kW. (Setting the temperature to "LO" appears to constantly use 1 to 1.5kW, so setting a target temperature does potentially use less power, but only if the user constantly adjusts the temperature to chase the cabin temp.)
    • After allowing the A/C to cool the cabin for less than a minute, Climate power raised to 5+kW.
    • After a few minutes more of operation, Climate power fell again to under 1kW. Allowing the system to continue to run resulted in the repeated cycling of the 5+kW Climate reading.
    • CONCLUSION: At warm outdoor temperatures (which in conjunction with greenhousing effects create uncomfortably warm cabin conditions), the A/C system can easily cool the cabin to the desired temp. When that temperature is achieved, the HVAC system energizes the heater to balance the refrigerated air. 
  • With outdoor temperature reported as 62°F, at night:
    • Turned on the HVAC system, and turned on the A/C (NOT using “Auto” mode).
    • Increased the target temperature until MyView’s Climate power increased to over 5kW - in this instance, this occurred at 64°F.
    • Reduced the target temperature to 62°F at which point Climate power dropped to around 1kW.
    • After allowing the A/C to cool the cabin for 20 minutes, Climate power never increased.
    • CONCLUSION: Uncertain. The implication is that the A/C system was incapable of reducing the cabin temperature enough for the interior thermometer to register 62°F. It’s unlikely that any user would wish to cool their cabin in these conditions, however.

Sunday, May 11, 2014

10 Things You Should Know About Charging Electric Vehicles

This is a recap of concepts I've covered at length in previous posts.
  • 1) It's pointless to be able to "search for nearby charging stations," unless you're prepared to wait at least 1 hour for every 20 miles of charge you need.
  • 2) There aren't nearly enough public charging sites to actually matter. If one happens to be in walking distance of a place you need to go, consider yourself lucky. (By the same token, if you know of a charging site at which you'd like to charge, it's not likely to be available - see #5.)
  • 3) Yes, you can travel further than the full range of your EV's battery by stopping to charge. But if you do not plan carefully, you will either be stranded or find yourself sitting in your car for hours while it charges.
  • 4) Public charging stations work, but how useful they are depends upon your level of commitment and/or spirit of adventure.
  • 5) There's no guarantee or even likelihood that any given public EVSE will be available. It may be:
    • non-existent
    • non-operational (broken, or never completed as an installation project)
    • charging another EV
    • inaccessible because an EV or ICE (internal-combustion engine) vehicle is using the space only for parking
  • 6) Even though most public charging stations deliver around 6-7kW (kilowatts), some don't.
    • Those that can achieve at least 6-7kW replenish most vehicles at about 20 miles/hour. But some vehicles can only charge at about half that rate (i.e., some Nissan Leaf models have only 3.3kW chargers), and some public EVSEs don't provide more than 2-3kW, even to vehicles capable of charging at higher rates.
  • 7) Most for-pay public charging stations provide a way for EV users who have not previously established an account to pay for charging.
    • This involves a telephone call, a credit card, and a way to identify the charging station.
  • 8) For-pay charging services may bill: a) by the hour of charging; b) by the kilowatt-hour (amount of electricity transferred); or c) by the hour of being plugged in (regardless of charging).
  • 9) Regardless of your vehicle's battery capacity, the time required to replenish the battery at most public charging sites is about the same:
    • Most "Level 2" EVSEs provide around 6 kilowatts, providing about 20 miles of range for every hour of charging.
  • 10) For many users, public charging is irrelevant. If you don't drive more than 70 miles a day, don't worry about it.