Plug-in Hybrid Electric Vehicle
The next step towards electrifying the powertrain is moving to the plug-in hybrid electric vehicle(PHEV). The PHEV is a commuter car with a serial configuration that runs mostly on battery. It has no mechanical powertrain and relies solely on electric motors for propulsion. Instead of the IC engine transferring kinetic power directly to the wheels, as is common with the HEV, the IC engine engages only when the batteries get low to activate a generator and produce electricity for the electric motors. A fully charged battery is good for about 50km (30 miles), and the IC engine with generator has adequate power to drive beyond this distance.
The PHEV is ideal for commuting and doing errands in the neighborhood. When driving on the batteries there is no gasoline consumption, nor is there a gas tax and the roads are virtually free to use. PHEV users will notice only small increases in their utility bills for charging the batteries at home. No more hefty bills at gas stations — or so it seems.
Unlike the parallel HEV that relies on the battery for brief moments, the PHEV battery is in charge depletion mode,meaning that the battery must work harder than with the HEV. This adds stress and reduces longevity. While a capacity drop to 39 percent, as seen on the Toyota Prius battery in Table 12-3, has little effect on the overall performance of an HEV, the same loss on a PHEV would reduce the driving distance from the specified 50km to 20km (30 to 12 miles) before the IC engine kicks in. This would likely call for a battery replacement.
The Chevy Volt is one of the first PHEV cars. The 181kg (400 lb) battery has 220 Li-ion cells and stores 16kWh of energy to drive a 149hp (111kW) electric motor. Each prismatic cell has the size and shape of a paperback book. Temperature control keeps the battery at 20–25°C (68–77°F) during driving and while charging. An 115VAC outlet fills the battery in eight hours; a 230VAC reduces the charging time to three hours. GM specifies a commute of 64km (40 miles) before the 1.4-liter four-cylinder IC engine kicks in to activate the 53kW AC generator that powers the electric motors. Capacity fade with aging will manifest itself in reduced driving distance before the IC engine kicks in.
As good as the PHEV sounds, the long-term savings may be smaller than expected, especially if a battery replacement is necessary during the life of a car. With careful use and proper maintenance, a modern car can go for 15–20 years on the original IC engine; a battery replacement with the PHEV will likely be necessary at the car’s mid life point. Menahem Anderman, a leading expert on advanced automobile batteries, says we still haveno suitable battery for the PHEV and expresses concern that the reliability of lithium-ion technology for automotive applications has not yet been proven.
To obtain an acceptable driving range, the PHEV needs a battery that is five times larger than that of the HEV. While the HEV gets by with a moderate-size battery of 1–2kW, the PHEV battery is in the 5–15kWh range and costs up to $12,000. Car manufacturers must provide an eight-year warranty and the capacity threshold has yet to be determined.
Battery aging is an issue that car manufacturers avoid mentioning in fear of turning potential buyers away, and this concern increases with the PHEV. While we accept runtime declines on our cell phones and laptops and adjust to lower expectations accordingly, a car buyer paying big money for new technology may not be so forgiving. The motorist is familiar with ample power and minimal degradation in performance as the car ages and when driving in cold temperatures. The battery cannot match this performance, and the owner will need to tolerate a decrease in distance driven during winter, as well as accept a small reduction in delivered mileage with each advancing year due to battery aging. While a $2,000–3,000 battery replacement is feasible for an HEV, the $10,000–12,000 PHEV battery will determine the life of the car.
Modern cars do more than provide transportation; they also include amenities for safety, comfort and pleasure. The most basic of these are the headlights and windshield wipers. Buyers also want heating and air-conditioning, services that are taken for granted with IC-powered vehicles but will need to be used sparingly in a PHEV. Heat that is a natural by-product from the IC engine must be generated with battery power in the PHEV. The larger concern is air-conditioning; an AC unit to cool the cabin draws 3–5kW of power.
Many PHEV buyers will overlook these concerns; they value the environmental benefit and the pleasure of driving a vehicle powered by electricity. The drivers will adapt to a new lifestyle routine — wherein they charge their vehicle at night when the electric grid has excess capacity and drive measured distances during the day. Users of these cars will also appreciate the new charging stations being installed at workplaces and shopping malls.
Comments
Yeah, like they can’t say ‘my car broke’ now.
yeah phev vehicles are good but imagine the cost of maintenance. maybe in 5 to 10 years we will see the complaints of maintaining these cars. i am happy to stick with petrol cars i just have some minor problems like my door panels for cars are broken. so far no other problems.
Is it possible to charge and discharge a battery simultaneously?
Can I use the solar panels to charge the battery while the electric motor in the electric vehicle and is connected to the batteries ie.the batteries are discharging?
but of course your going to have people who forget to charge their car at night and then get angry when they cant get to work in the morning.
more people will use car excuses to have sickies “I put my car on charge but we had a blackout” etc