Mild hybrids (also known as power-assist hybrids, battery-assisted hybrid vehicles or BAHVs) are generally cars with an

internal combustion engine An internal combustion engine (ICE or IC engine) is a heat engine in which the combustion of a fuel occurs with an oxidizer (usually air) in a combustion chamber that is an integral part of the working fluid flow circuit. In an internal combus ...

equipped with an

electric machine In electrical engineering, electric machine is a general term for machines using electromagnetic forces, such as electric motors, electric generators, and others. They are electromechanical energy converters: an electric motor converts electricity ...

(one motor/generator in a

parallel hybrid Hybrid vehicle drivetrains transmit power to the driving wheels for hybrid vehicles. A hybrid vehicle has multiple forms of motive power. Hybrids come in many configurations. For example, a hybrid may receive its energy by burning gasoline, but sw ...

configuration) allowing the engine to be turned off whenever the car is coasting, braking, or stopped, and then quickly restarted once power is again required. Mild hybrids may employ

regenerative braking Regenerative braking is an energy recovery mechanism that slows down a moving vehicle or object by converting its kinetic energy into a form that can be either used immediately or stored until needed. In this mechanism, the electric traction mo ...

and some level of power assist to the internal combustion engine (ICE), but mild hybrids do not have an electric-only mode of propulsion.

Overview

The mild hybrid's

electric motor An electric motor is an Electric machine, electrical machine that converts electrical energy into mechanical energy. Most electric motors operate through the interaction between the motor's magnetic field and electric current in a Electromagneti ...

provides greater efficiency through the use of a single device that is essentially an integrated starter/alternator sometimes known as a generator-motor unit. A typical mild-hybrid setup uses a belt-powered generator-motor unit driven off the engine to supply power to a small battery. The generator is also powered through regenerative braking, enabling power that would otherwise be dissipated as heat to be recaptured and recovered for use in powering the vehicle. The small power assist generated by mild-hybrid systems can help supplement the gas engine in low-speed situations or handle the demands of engine start/stop functionality. Vehicles equipped with a mild-hybrid system typically see anywhere from a 1–4 miles per gallon improvement in fuel economy relative to comparable models without the technology. Mild hybrids do not require the same level of battery power and do not achieve the same levels of fuel economy improvement as compared to

full hybrid Hybrid vehicle drivetrains transmit power to the driving wheels for hybrid vehicles. A hybrid vehicle has multiple forms of motive power. Hybrids come in many configurations. For example, a hybrid may receive its energy by burning gasoline, but sw ...

models. One example is the 2005-07

Chevrolet Silverado The Chevrolet Silverado is a range of trucks manufactured by General Motors under the Chevrolet brand. Introduced for the 1999 model year, the Silverado is the successor to the long running Chevrolet C/K model line. Taking its name from th ...

, Parallel Hybrid Truck (PHT) a full-size

pickup truck A pickup truck or pickup is a light-duty truck that has an enclosed cabin, and a back end made up of a cargo bed that is enclosed by three low walls with no roof (this cargo bed back end sometimes consists of a tailgate and removable covering) ...

with a single 7 kW 3-phase electric motor mounted in the bell-housing between the engine and a conventional 4L60E transmission. Chevrolet was able to get a 10% improvement on the Silverado's city

fuel efficiency Fuel efficiency is a form of thermal efficiency, meaning the ratio of effort to result of a process that converts chemical potential energy contained in a carrier (fuel) into kinetic energy or work. Overall fuel efficiency may vary per device, wh ...

by shutting down and restarting the engine on demand, and the reduction of parasitic accessory loads. However the PHT had no power assist features or all-electric "electric vehicle" (EV) capability, and very limited

features.

Advantages and disadvantages

Compared with a

vehicle, mild hybrids may provide some of the benefits of the application of hybrid technologies, with less of the cost–weight penalty that is incurred by installing a full hybrid series-parallel drivetrain. Fuel savings would generally be lower than expected with use of a full hybrid design, as the design does not facilitate high levels of

or necessarily promote the use of smaller, lighter, more efficient internal combustion engines.

Examples

General Motors

General Motors The General Motors Company (GM) is an American Multinational corporation, multinational Automotive industry, automotive manufacturing company headquartered in Detroit, Michigan, United States. It is the largest automaker in the United States and ...

mild hybrids including the

Parallel Hybrid Truck The Chevrolet Silverado is a range of trucks manufactured by General Motors under the Chevrolet brand. Introduced for the 1999 model year, the Silverado is the successor to the long running Chevrolet C/K model line. Taking its name from the ...

(PHT) and numerous cars and SUVs equipped with the BAS Hybrid system, often use a 36- to 48-volt system to supply the power needed for the startup motor, as well as a source of power to compensate for the increasing number of electronic accessories on modern vehicles. GM's belt alternator starter (BAS) mild hybrid system uses a belt drive to start the

(ICE) through its motor–generator unit (MGU), then once started the engine drives the 14.5 kW motor-generator to charge the batteries. The BAS hybrid system also utilizes

to replenish the system's 36 V battery and can provide moderate levels of power assist. According to the EPA, a 2009 Saturn Vue Greenline equipped with the BAS Hybrid system delivers a 27% improvement in combined fuel economy over the non-hybrid version (FWD 4cyl).

Honda

Honda's

Integrated Motor Assist Integrated Motor Assist (commonly abbreviated as IMA) is Honda's hybrid car technology, introduced in 1999 on the Insight. It is a specific implementation of a parallel hybrid. It uses an electric motor mounted between the internal combustion e ...

directly attaches a brushless DC motor between the flywheel and transaxle, providing both assistance during acceleration and regeneration during coasting/braking. It has been produced in various voltages and power outputs, as dictated by the size and weight of the vehicle application. Models equipped with the

include the

Honda Insight The is a hybrid electric vehicle that is manufactured and marketed by Honda. Its first generation was a two-door, two passenger liftback (1999–2006) and in its second generation was a four-door, five passenger liftback (2009–2014). In its ...

(1999–2006, 2009–2014),

Honda Jazz The Honda Jazz nameplate has been used by the Japanese manufacturer Honda to denote several different motorized vehicles since 1982: * 1982–1986 — The first generation Honda City when marketed in Europe, as Opel owned the City name * ...

(2011– )

Honda Civic The is a series of automobiles manufactured by Honda since 1972. Since 2000, the Civic has been categorized as a compact car, while previously it occupied the subcompact class. , the Civic is positioned between the Honda Fit/City and Honda Acc ...

(2003–2015),

Honda Accord The , also known as the in Japan and China for certain generations, is a series of cars manufactured by Honda since 1976, best known for its four-door sedan variant, which has been one of the best-selling cars in the United States since 1989. ...

(2005–2007), and

CR-Z The Honda CR-Z is a sport compact hybrid electric automobile manufactured by Honda and marketed as a "sport hybrid coupe." The CR-Z combines a hybrid gasoline-electric powertrain with traditional sports car elements, including a 2+2 seating arran ...

(2010–2016).

Others

During the 2008 Olympic Games in Beijing in August, Chinese automobile manufacturer

Chang'an Motors Chang'an Automobile Co., Ltd. is a Chinese state-owned automobile manufacturer headquartered in Jiangbei, Chongqing.Infineon Infineon Technologies AG is a German semiconductor manufacturer founded in 1999, when the semiconductor operations of the former parent company Siemens AG were spun off. Infineon has about 50,280 employees and is one of the ten largest semicond ...

Toyota is a Japanese multinational automotive manufacturer headquartered in Toyota City, Aichi, Japan. It was founded by Kiichiro Toyoda and incorporated on . Toyota is one of the largest automobile manufacturers in the world, producing about 10 ...

sold mild hybrid versions of the

Toyota Crown The is an automobile which has been produced by Toyota in Japan since 1955. It is primarily a line of mid-size luxury cars that is marketed as an upmarket offering in the Toyota lineup. Introduced in 1955 as the Toyopet Crown, it has served ...

executive sedan between 2001 and 2003 and the mid-size Crown Sedan between 2002 and 2008 in the Japanese domestic market. These models combined a BAS hybrid system with the standard straight-6 petrol engines for increased fuel economy. Toyota now sells a full hybrid version of the Crown under their brand name

Hybrid Synergy Drive Hybrid Synergy Drive (HSD), also known as Toyota Hybrid System II, is the brand name of Toyota Motor Corporation for the hybrid car drive train technology used in vehicles with the Toyota and Lexus marques. First introduced on the Prius, the tec ...

MINI The Mini is a small, two-door, four-seat car, developed as ADO15, and produced by the British Motor Corporation (BMC) and its successors, from 1959 through 2000. Minus a brief hiatus, original Minis were built for four decades and sold during ...

and BMW have start and stop, and some with regenerative braking, in all of their vehicles sold in Europe running 4-cylinder engines with manual transmissions.

Citroën Citroën () is a French automobile brand. The "Automobiles Citroën" manufacturing company was founded in March 1919 by André Citroën. Citroën is owned by Stellantis since 2021 and previously was part of the PSA Group after Peugeot acquired ...

proposes a stop and start system on its C2 and C3 models. The concept-car ''C5 Airscape'' has an improved version of that, adding regenerative braking and traction assistance functionalities, and

ultracapacitors A supercapacitor (SC), also called an ultracapacitor, is a high-capacity capacitor, with a capacitance value much higher than other capacitors but with lower voltage limits. It bridges the gap between electrolytic capacitors and Rechargeable ba ...

for energy buffering. In 2004 VW brought two mild hybrid concept cars to Shanghai for the Challenge Bibendum.

Suzuki is a Japan, Japanese multinational corporation headquartered in Minami-ku, Hamamatsu, Japan. Suzuki manufactures automobiles, motorcycles, All-terrain vehicle, all-terrain vehicles (ATVs), outboard motor, outboard marine engines, wheelchairs ...

have announced the

Suzuki Baleno The Suzuki Baleno nameplate has been used by the Japanese manufacturer Suzuki to denote several different subcompact cars since 1996. * From 1996 to 2002, the Suzuki Baleno that was sold in Europe and Asia-Pacific was a rebadged Suzuki Cultus C ...

with integrated SHVS-technology in 2016 on the new

Suzuki HEARTECT platform The HEARTECT platform is an automobile platform that underpins various Suzuki models since 2014. __TOC__ Construction The platform is claimed to utilize " Advanced High Tensile Steel" and "Ultra High Tensile Steel", which are intended to incr ...

. Suzuki has had experience with this mild-hybrid technology in their

Suzuki Ciaz The Suzuki Ciaz is a subcompact sedan produced by Suzuki since 2014. It is developed to replace the Suzuki SX4 sedan in several Asian, African and Latin American markets. It went on sale for the first time in India, the largest market for Suzuk ...

References

{{Reflist Hybrid powertrain Hybrid vehicles de:Hybridelektrokraftfahrzeug#Mild-Hybrid