Going Electric: Things to Consider

What you should know before you buy an all-electric vehicle

9 September 2011

There’s a lot of excitement about those new all-electric automobiles, but you may experience several drawbacks if you do buy one, according to Saifur Rahman, an IEEE Fellow and director of Virginia Tech’s Advanced Research Institute, in Arlington. For instance, several electric vehicles on one residential street can contribute to a brownout or even a blackout by overloading the local distribution transformer. If you are on the road, you may find it difficult to recharge your vehicle because even though EV charging stations are being built, they are still few and far between. And there are significant environmental concerns about the disposal of used up EV batteries in landfills. 


TRANSFORMER TROUBLE
Buy an all-electric and you may also have to pay for a home charging station to recharge your battery. The stations come in three varieties. A Level 1 charger plugs into a regular 110/120-volt, 20-ampere outlet. But it may take longer than one night to do its job. Anywhere from 10 to 21 hours is more like it, depending on the car model and the battery.


A Level 2 unit is heftier, a dedicated 220/240-V, 40-A unit that must be installed by an electrician. This is the type EV automakers recommend you use. It could take about three hours to charge a battery that’s half depleted and about eight hours to charge a battery that’s dead, depending on the car model. Rahman estimates a Level 2 charger will cost about US $2000 in the United States, plus the electrician’s fee.


Level 3 chargers will go into the quick-charging, 480-V stations that owners of all-electrics hope will be popping up everywhere. Chargers at such stations could bring a half-charged EV battery to full capacity in 10 to 30 minutes. Such setups, said to be in the planning stages in many cities, will be the “gas stations” for all-electrics.


But if your neighborhood has too many all-electrics plugged in and if no load-control programs are added, there is a chance the local transformers could be overloaded. Most pole-mounted transformers in the United States are rated at 50 000 volt-amperes (50 kVA) and typically serve four to eight homes. At any time, each home could be pulling in about 8 kilowatts, but plug in two or three EVs drawing 5 kW or more each, turn on a few 240-V appliances such as air conditioners, electric ovens, or clothes dryers—each of which draws from 5 to 7 kW—and you and your neighbors could be sitting in the dark.


“The impact of electric vehicles will be felt at the local distribution point—the home,” says Rahman, who does see a bright side. “Because the number of EV owners will be small at first and spread across different time zones, transmission- or generation-level overloads will not be a problem, as some claim.”


Installing larger pole-mounted transformers providing 100 kVA or more could help. Installed, each of these would cost several thousand dollars, but the question is, Who will pay for that? It’s unreasonable to ask consumers without an EV to come up with the money, Rahman says. Nor is it feasible to ask the few initial electric car owners. Rahman suggests that rather than upgrading the transformer, it makes more sense to add a control device on each charging station that turns off other 240-V appliances in the home when the EV needs to be charged, or delay charging the car.


“This station could be made intelligent enough to sense when other 240-V devices are running,” he explains. “If it senses two appliances are on and there’s not enough capacity in the transformer, it will either turn off the appliances or not charge the car. This will make the electric car transparent to the power company.” Such a feature, he says, could be added at a small cost.


CHARGING DILEMMA

Another problem is finding a place to put the charging station. If you live in a house with a garage, charging your car should be relatively simple. But you’ll have a real problem if you live in an apartment or town house and don’t have an assigned parking spot with room for a charging station.


The options are limited. A Level 2 home charging station would be hard-wired to your house, so you couldn’t take it with you to your sister’s or bring it to your workplace and plug in your car. That means you’ll probably need a public charging station. These will be expensive, so don’t expect to see them anytime soon in public garages, in your company parking lot, or sprouting along highways. Public stations will require a new infrastructure, involving 240-V lines with several hundred amperes of spare capacity for EVs—which might not always be available. A roadway station that can charge four to eight EVs at a time could cost upward of $25 000 to build, Rahman says.


“Running the lines costs money, and existing garages may not have the physical space and/or spare electrical capacity to add stations,” says Rahman, who calls building such stations “a significant bottleneck” to EV sales, one that will likely be overcome only by government incentives.


The slow speed of charging the battery will also affect the infrastructure, with cars potentially tying up Level 2 charging stations for several hours, though it’s expected that the roadway stations will use 480 V.


BATTERY BRIEFING

Cars such as the Chevrolet Volt, Ford Focus Electric [below], and Nissan Leaf warranty their proprietary battery packs for eight years or 161 000 km, whichever comes first. The Volt relies on a 16-kilowatt-hour manganese spinel lithium-polymer prismatic battery pack for its 64-km range. The Leaf uses a 24-kWh lithium-nickel-manganese polymer battery for a 160-km range. The Focus Electric can go 160 km with its 23-kWh lithium-ion battery pack.


But battery capability fades with time. A battery delivers less range after a couple of thousand charge-discharge cycles. Battery life is also affected by how people drive, whether the battery is charged in minutes or hours, and the climate. An EV’s range will decrease as it ages—and the more aggressively it is driven, the faster that happens.


As the batteries are improved, they could last 10 years, longer than the life of many vehicles. But replacing a failed battery could cost from $3000 to $12 000, depending on the car model.


“And if your battery goes dead, you can’t simply run to your local garage for a replacement,” Rahman points out.


Then there’s the dilemma of what to do with spent batteries. According to the U.S. Environmental Protection Agency, rechargeable batteries are not an environmental hazard if they are not dumped in landfills. But the European Union has a battery recycling law requiring vendors to reclaim for recycling at least a quarter of the batteries they manufacture and sell, including lithium-ion. 


“Because the ion of lithium is not a benign metal, it will have an impact on the environment,” Rahman says. 


As the EV batteries age, their ability to hold charge will diminish, but they can still be useful in homes and offices as backup sources of electricity, Rahman points out. “For example, if homeowners or small businesses want to have high-quality power for short durations (maybe several hours) for whatever reason or to avoid peaking charges by not using as much electricity when the power company faces supply crises, these discarded EV batteries can meet those needs. As these opportunities are identified and the value of such applications are realized, a secondary market will grow to trade for such batteries.”


Read more in this issue to learn what IEEE is doing in the area of all-electric and hybrid vehicles, including conferences and standards as well as projects undertaken by IEEE student members.

Learn More