A range extender is a fuel-based auxiliary power unit (APU) that extends the range of a battery electric vehicle by driving an electric generator that charges the vehicle's battery. This arrangement is known as a series hybrid drivetrain. The most commonly used range extenders are internal combustion engines, but fuel-cells or other engine types can be used. [1]
Range extender vehicles are also referred to as extended-range electric vehicles (EREV), range-extended electric vehicles (REEV), and range-extended battery-electric vehicle (BEVx) by the California Air Resources Board (CARB). [2]
Many range extender vehicles, including the Chevrolet Volt and the BMW i3, are able to charge their batteries from the grid as well as from the range extender, and therefore are a type of plug-in hybrid electric vehicle (PHEV). [3] [4] Historically PHEV, HEV and MHEV were primarily powered by combustion (bigger engine and fuel tank with smaller battery and electric motor(s)). While EREV are the opposite. [5]
The key function of the range extender is to increase the vehicle's range. Range autonomy is one of the main barriers for the commercial success of electric vehicles, and extending the vehicle's range when the battery is depleted helps alleviate range anxiety. [6]
A range extending vehicle design can also reduce the consumption of the range extending fuel (such as gasoline) by using the primary fuel (such as battery power), while still maintaining the driving range of a single fuel vehicle powered by a range extending fuel such as gasoline. The range extending fuel is generally considered to be less environmentally and economically friendly to use than the primary fuel source, so the vehicle control system gives preference to using the primary fuel if it's available. However, due to range limitations with the primary fuel source, the range extending fuel allows the vehicle to get many of the cost and environmental benefits of the primary fuel, while maintaining the full driving range of the range extending fuel source. [7] That said, the benefits (cost, carbon emissions) derived from using a vehicle with a range extender ultimately depend on how the vehicle is driven, and in particular how often the range extender is used. [8]
As an example, cars such as the Chevrolet Volt and the BMW i3 with optional range extender are equipped with sufficiently large batteries to drive 80–160 km (50–100 miles), which is enough for many trips but not sufficient to drive long distances. As such, the driver may use battery power for commuting and daily driving, but still be able to drive from New York to Boston (about 320 km, 200 miles) by using the auxiliary gasoline internal combustion engine, without stopping frequently to charge the battery (which can take hours). The vehicle owner therefore accrues the benefits of using cheaper and less carbon-intensive electric power for most driving, while maintaining the ability to embark on longer trips with the same vehicle.
When a range extender uses conventional fuels they can re-fuel at regular fuel stations, which provides them with a similar driving range to conventional automobiles. [9] [10] [11]
As an REEV is only propelled by the electric motor it can do away with the weight and cost associated with the gearbox transmission system typically used in internal combustion engine cars. Further, as the range extender does not need to increase or decrease output in line with the power needs of the vehicle (this task is handled by the electric motor) the range extender can be sized to satisfy the vehicle's average power requirement rather than its peak power requirement (such as when accelerating). The range extender can also operate much closer to its most efficient rotational speed. These design features allow an REEV to convert fossil fuel energy to electric power and vehicle motion relatively efficiently.
According to 2012 Amendments to the Zero Emission Vehicle Regulations adopted in March 2012 by the California Air Resources Board (CARB), a range-extended battery-electric vehicle, designated as BEVx, should comply, among others, with the following criteria: [2]
Range extenders are commonly used in marine (autonomous underwater vehicle), aircraft and Generator/Utility, automotive [13] and hybrid electric vehicle applications. [14]
General Motors describes the Chevrolet Volt as an electric vehicle equipped with a 16 kWh battery plus a "range extending" gasoline powered internal combustion engine (ICE) as a genset and therefore dubbed the Volt an "Extended Range Electric Vehicle" or E-REV. [3] [4] [15] In a January 2011 interview, the Chevy Volt's Global Chief Engineer, Pamela Fletcher, referred to the Volt as "an electric car with extended range." [16] The Volt operates as a purely electric car for the first 40–80 km (25–50 miles) in charge-depleting mode. When the battery capacity drops below a pre-established threshold from full charge, the vehicle enters charge-sustaining mode, and the Volt's control system will select the most optimally efficient drive mode to improve performance and boost high-speed efficiency. [3] [17] [18]
According to General Motors' real time tally of the distance driven by Volt owners in North America, by mid June 2014 they had accumulated more than 800 million all-electric km (500 million miles). GM also reported that Volt owners driving is more than 63% in all-electric mode. Volt owners who charge regularly typically drive more than 1,560 km (970 miles) between fill-ups and visit the gasoline station less than once a month. [19] A similar report, issued by GM in August 2016, reported that Volt owners have accumulated almost 2.4 billion km (1.5 billion miles) driven in EV mode, representing 60% of their total distance traveled. [20]
The BMW i3 all-electric car with at least 22 kWh battery capacity offers an optional gasoline-powered range extender APU. [21] The range extender is the same 647 cc two-cylinder gasoline engine used in the BMW C650 GT scooter with a 9 L (2.0 imp gal; 2.4 US gal) fuel tank. The US model originally had its tank electronically limited to a smaller 7 L capacity. [22] The range extender engages when the battery level drops to 6%. It generates electricity to extend the range from 130–160 km (80–100 miles) to 240–300 km (150–190 miles) [23] [24] Performance in range-extending mode may be more limited than when it is running on battery power, as BMW designed the range extender as a backup to enable reaching a recharging location. [25]
According to BMW, at the beginning of the i3 release, the use of range-extender was much more than the carmaker expected, more than 60%. Over time it has decreased significantly, with some people almost never using it, and by 2016 it is being regularly used in fewer than 5% of i3s. [26]
The range-extender option costs an additional US$3,850 in the United States, [27] an additional €4,710 (~ US$6,300) in France, [28] and €4,490 (~ US$6,000) in the Netherlands. [29]
The range-extender option of the BMW i3 was designed to meet the CARB regulation for an auxiliary power unit (APU) called REx. According to rules CARB adopted in March 2012, the 2014 BMW i3 with a REx unit fitted will be the first car to qualify as a range-extended battery-electric vehicle or "BEVx." CARB describes this type of electric vehicle as "a relatively high-electric range battery-electric vehicle (BEV) to which an APU is added." The APU, which maintains battery charge at about 6% after the pack has been depleted in normal use, is strictly limited in the additional range it can provide. [2] [30]
Other range-extended electric vehicles include the discontinued Cadillac ELR and the discontinued Fisker Karma. [31] [32] [33] In June 2016, Nissan announced it will introduce a compact range extender car in Japan before March 2017. The series plug-in hybrid will use a new hybrid system, dubbed e-Power, which debuted with the Nissan Gripz concept crossover showcased at the 2015 Frankfurt Auto Show. [34] The technology, without the plug-in ability, had been deployed to the Nissan Note e-Power and Nissan Kicks e-Power.
The LEVC TX London taxi was launched in 2017 and features a 33 kWh battery that is charged by a 1.5-litre gasoline engine. [35]
The Li Auto One is a large SUV which combines a 41-kWh battery with a small 1.2-litre gasoline engine. [36] [37]
This approach has also been used for heavy vehicles, such as Wrightbus's Gemini 2 [38] and New Routemaster [39] buses.
Hydrogen fuel cells have also been used as a range extender for battery electric buses, allowing them to have greater range. [40] For example, the Mercedes-Benz eCitaro has a range of 280 kilometres (170 mi) as a battery electric model, with the eCitaro fuel cell bus having a range of 400 kilometres (250 mi) thanks to a 60kW Toyota fuel cell that recharges the battery. [41]
Ford has patents for a bed mounted gasoline-powered generator for their fully electric pickups. [42] Rivian has patents for bed mounted additional batteries for increased range. [43] Rivian electric trucks can charge each other for extended range. [44]
The 2010 Wolverine 3 program included an ICE range extender for its unmanned aerial vehicle. [45]
A range-extended electric vehicle uses a series hybrid drivetrain.
A hybrid vehicle is one that uses two or more distinct types of power, such as submarines that use diesel when surfaced and batteries when submerged. Other means to store energy include pressurized fluid in hydraulic hybrids.
A green vehicle, clean vehicle, eco-friendly vehicle or environmentally friendly vehicle is a road motor vehicle that produces less harmful impacts to the environment than comparable conventional internal combustion engine vehicles running on gasoline or diesel, or one that uses certain alternative fuels. Presently, in some countries the term is used for any vehicle complying or surpassing the more stringent European emission standards, or California's zero-emissions vehicle standards, or the low-carbon fuel standards enacted in several countries.
A plug-in hybrid electric vehicle (PHEV) or simply plug-in hybrid is a type of hybrid electric vehicle equipped with a rechargeable battery pack that can be directly replenished via a charging cable plugged into an external electric power source, in addition to charging internally by its on-board internal combustion engine-powered generator. While PHEVs are predominantly passenger cars, there are also plug-in hybrid variants of sports cars, commercial vehicles, vans, utility trucks, buses, trains, motorcycles, mopeds, military vehicles and boats.
Mild hybrids (MHEV) are generally cars with an internal combustion engine (ICE) equipped with a minimally extended battery and an auxiliary electric combined motor and generator in a parallel hybrid configuration that is not enough for an electric-only mode of propulsion but does allow the engine to be stopped whenever the car is coasting, braking, or stopped, and then restarted once power is required again. Mild hybrids may employ regenerative braking and some level of power assist to the internal combustion engine.
Hybrid vehicle drivetrains transmit power to the driving wheels for hybrid vehicles. A hybrid vehicle has multiple forms of motive power.
A hybrid electric vehicle (HEV) is a type of hybrid vehicle that combines a conventional internal combustion engine (ICE) system with an electric propulsion system. The presence of the electric powertrain is intended to achieve either better fuel economy than a conventional vehicle or better performance. There is a variety of HEV types and the degree to which each functions as an electric vehicle (EV) also varies. The most common form of HEV is the hybrid electric car, although hybrid electric trucks, buses, boats, and aircraft also exist.
An alternative fuel vehicle is a motor vehicle that runs on alternative fuel rather than traditional petroleum fuels. The term also refers to any technology powering an engine that does not solely involve petroleum. Because of a combination of factors, such as environmental and health concerns including climate change and air pollution, high oil-prices and the potential for peak oil, development of cleaner alternative fuels and advanced power systems for vehicles has become a high priority for many governments and vehicle manufacturers around the world.
The Chevrolet Volt is a plug-in hybrid car that was manufactured by General Motors, and also marketed in rebadged variants as the Holden Volt in Australia and New Zealand and the Buick Velite 5 in China, and with a different fascia as the Vauxhall Ampera in the United Kingdom and as the Opel Ampera in the remainder of Europe. Volt production ended in February 2019.
All-electric range (AER) is the maximum driving range of an electric vehicle using only power from its on-board battery pack to traverse a given driving cycle. In the case of a Battery electric vehicle (BEV), it means the maximum range per recharge, typically between 150 and 400 miles. For a plug-in hybrid electric vehicle (PHEV), it means the maximum range in charge-depleting mode, typically between 20 and 40 miles. PHEVs can travel considerably further in charge-sustaining mode which utilizes both fuel combustion and the on-board battery pack like a conventional hybrid electric vehicle (HEV).
The history of plug-in hybrid electric vehicles (PHEVs) spans a little more than a century, but most of the significant commercial developments have taken place after 2002. The revival of interest in this automotive technology together with all-electric cars is due to advances in battery and power management technologies, and concerns about increasingly volatile oil prices and supply disruption, and also the need to reduce greenhouse gas emissions. Between 2003 and 2010 most PHEVs on the roads were conversions of production hybrid electric vehicles, and the most prominent PHEVs were aftermarket conversions of 2004 or later Toyota Prius, which have had plug-in charging and more lead–acid batteries added and their electric-only range extended.
Voltec, formerly known as E-Flex, is a General Motors powertrain released in November 2010. The Voltec architecture is primarily a plug-in capable, battery-dominant electric vehicle with additional fossil fuel powered series and parallel hybrid capabilities.
Miles per gallon gasoline equivalent is a measure of the average distance traveled per unit of energy consumed. MPGe is used by the United States Environmental Protection Agency (EPA) to compare energy consumption of alternative fuel vehicles, plug-in electric vehicles and other advanced technology vehicles with the energy consumption of conventional internal combustion vehicles rated in miles per U.S. gallon.
The Cadillac ELR is a two-door, four-passenger luxury plug-in hybrid compact coupé manufactured and marketed by Cadillac for model years (MY) 2014 and 2016 – with a hiatus for MY 2015. Using a retuned version of the Chevrolet Volt's Voltec EREV drivetrain, the ELR's lithium-ion battery pack delivered an all-electric range of 37–39 miles (60–63 km) and a top speed of 106 mph (171 km/h).
The BMW i8 is a plug-in hybrid sports car developed by BMW. The i8 was part of BMW's electrified fleet and was marketed under the BMW i sub-brand. The production version of the BMW i8 was unveiled at the 2013 Frankfurt Motor Show and was released in Germany in June 2014. Deliveries to retail customers in the U.S. began in August 2014. A roadster variant was launched in May 2018. Production ended in June 2020.
The BMW ActiveE was a demonstration electric car based on the BMW 1 Series small family cars. It was the second vehicle after the Mini E to be developed under BMW Group’s Project i. The electric drive system was the latest addition to BMW’s EfficientDynamics programme. The US Environmental Protection Agency official range is 151 kilometres (94 mi), with an energy consumption of 33 kW·h/100 miles, and the agency rated the ActiveE's combined fuel economy at 2.3L/100 km.
Range anxiety is the driver's fear that a vehicle has insufficient energy storage to cover the road distance needed to reach its intended destination, and would thus strand the vehicle's occupants mid-way. The term, which is now primarily used in reference to the practical driving range of battery electric vehicles (BEVs), is considered to be one of the major psychological barriers to large-scale public adoption of electric cars.
The BMW i3 is an electric car that was manufactured by German marque BMW from 2013 to 2022. The i3 was BMW's first mass-produced zero emissions vehicle and was launched as part of BMW's electric vehicle BMW i sub-brand. It is a B-segment, high-roof hatchback with an electric powertrain. It uses rear-wheel drive via a single-speed transmission and an underfloor lithium-ion battery pack with an optional range-extending petrol engine.
The BMW i is a sub-brand of BMW founded in 2011 to design and manufacture plug-in electric vehicles. The company initially released two vehicles: the i3 all-electric car and the i8 plug-in hybrid. The all-electric iX3 SUV was released in late 2020, while iX SUV and the i4 all-electric liftback sedan followed later in 2021.
The second generation Chevrolet Volt is a plug-in hybrid electric compact car produced by General Motors under the Chevrolet brand. It debuted at the 2015 North American International Auto Show to replace the original Volt, on sale since 2010. Retail deliveries as a 2016 model year began in October 2015 in the U.S. and Canada, and it was released in Mexico in December 2015. Availability of the 2016 model was limited to California and the other 10 states that follow California's zero emission vehicle regulations. It went on sale as a 2017 model year in the rest of the U.S. in February 2016. Volt production ended on February 15, 2019.
There are numerous versions of vehicle propulsion systems. Many of those came into fruition due to need for cleaner vehicles. Each of them might have many abbreviations and some might be misleading. This article explains shortly what defines them.