Electrification Technologies (Part 1): Continental's 48V mild hybrid

European introduction from 2016, widespread adoption projected for around 2020



 This report will take up mild hybrid systems equipped with Continental AG's 48-volt starter generators based on a lecture the company presented at the Automotive World expo in January 2016. Nissan Motor Co., Ltd.'s and Honda Motor Co., Ltd.'s strategies for electrification will be reported separately. 

 Regulations concerning fuel efficiency and CO2 emissions are being tightened in countries and regions all over the world. There are limits to how much internal combustion engines (ICE) can be improved in response to this, and several types of electrification are expected to be advanced. Widespread adoption of plug-in hybrid systems and 48-volt powered mild hybrid systems in particular is anticipated.

 Two models equipped with Continental's mild hybrid system (named "48-Volt Eco Drive" system by the company) will go on sale in Europe in 2016, and be launched in the U.S. and China between 2017 and 2018.

 Moreover, Continental is planning to introduce the Side-mounted Starter Generator system around 2020 and Inline Starter Generator system around 2025, both of which are advanced versions of the 48V Eco Drive system. Robert Bosch GmbH and Valeo S.A. have announced similar systems (described in the latter half of this report).

 In 2011, five German OEMs (Audi, Volkswagen, Porsche, Daimler, and BMW) agreed to formulate common specifications for 48V power supplies used in 48V mild hybrid systems. In 2013, they further defined the LV148 standard and requested the cooperation of parts suppliers. Because of this, underlying technology for 48V components is being readied for implementation. Compared to electric or full hybrid vehicles, OEMs did not need to assign significant development resources, which allowed for a set up where parts suppliers could make proposals.

 The main components are a belt starter generator, a lithium ion battery acting as a 48 V power supply, and a DC-DC converter for converting power from 48 volts to 12 volts. Continental's hybrid system adopts a 48V supply because power supplies that are 60 volts or higher must abide by stricter safety standards.


48 V hybrid prototype car
A 48V mild hybrid prototype car co-developed by Continental and Schaeffler that is based on the Ford Focus. The prototype improves fuel efficiency by 17% over the base model. It meets the Euro 6 emission standards. (Photo: Schaeffler)
48V Eco Drive systemのメリット
A conceptual image depicting the advantages of the
48V Eco Drive system (Photo: Continental)

Related Reports:
European OEMs and suppliers plan to launch 48V hybrid systems after 2016 (February 2015)
Latest electrification technologies:Bosch, Schaeffler, ZF, and Jatco (November 2015)

Tightening regulations on fuel economy and CO2 emissions around the world

 In Europe, which has the toughest CO2 emissions regulations, governments are calling for passenger car fleet average CO2 emissions to be lowered from 130g/km in 2015 to 95g/km by 2020/2021.

Regulations for passenger car CO2 emissions from 2020 onward

EU USA Japan China
2020/2021 2025 2020 2020
95g/km 97.8g/km 105g/km 116.8g/km

Source: ICCT (The International Council of Clean Transportation) (Note) The European Union requires 95% of new cars registered in 2020 and all new cars registered in 2021 to meet a regulated value of 95g/km. In 2015, the regulated value was 130g/km.

 The next chart indicates the measures Continental expects to be taken for reducing European CO2 emissions from 127 g/km in 2013 to 95 g/km in 2020. Figures on the green background indicate expected improvements of 11 to 14 g/km through electrification. 

EU: Measures being taken to achieve a CO2 emission target of 95 g/km in 2020

(gCO2/km) Current value Improvements Target
Market average as of 2013 127
Reduction of vehicle air resistance and weight 3-5
Combustion system improvements 10
Drivetrain efficiency (incl. engine friction reduction) 3
Powertrain electrification & Super-credits (see Note1) 4-7
Eco innovations (see Note2) 7
Connected Powertrains (navigation system linked to the cloud, etc.) 2-3
Improvement total and forecast for 2020 29-35 92-98
Target for 2020 95
(Notes) 1. Credit refers to preferential treatment when calculating CO2 emissions. Super-credits means bonus counting for sales of vehicles with low CO2 emissions (below 50 g/km) as 1.67 or 2 vehicles, and etc.
2. Eco-innovation refers to credits provided for new technologies that do not influence emissions tests, but result in CO2 reduction effects. These include examples like eco-mode buttons, adaptive cruise control, and bi-xenon or LED lights.



Forecasts for expansion of 48V mild hybrid vehicles

Market Development Continental forecasts that there will be 4 million 48V mild hybrid vehicles (HVs) around the world in 2020. It also anticipates that mass production will start reducing costs from around 2020, which will lead to period of greater growth, and that 48V systems will be equipped in 13 million vehicles in 2025.

Electrified vehicle market forecast

(Million vehicles)
2015 2020 2025
EV Less than 1 1 3
Plug-in + Full HV 2 6 11
48V Mild Hybrid 0 4 13
Total Less than 3 11 27

Source: Continental



Electrification by region and segment: 48V systems expanding in Europe and China

 The table below shows Continental's prediction about which segments in the global automotive market the various electric drive systems will find widespread adoption into.

 It is expected that Europe, where a 95 g/km emission regulation will come into force in 2020 and 2021, will see early popularization of 48V mild hybrid systems. The projection goes on to suggest that 48V systems will be widely used in the B through E segments, but that the B, C, and D vehicles segments in particular will see heavy adoption due to high demand for these vehicles and need to electrify them at low cost.

 Moreover, according to forecasts by AVL List GmbH, a provider of powertrain development and other engineering services, 48V systems will become prevalent in Europe and China and that almost all mild HVs will be powered by 48 V systems in these two regions. It is also highly likely that 48V systems will become prevalent in emerging markets other than China. Meanwhile, in Japan, the use of full hybrid and 12 V mild hybrid systems is forecasted to keep expanding in the future, but 48V systems are not expected to see much popularity.

 In addition to 48V mild HVs, European OEMs are concentrating their energies on building more plug-in hybrid vehicles (PHVs) in the D and E segments. Many of these are heavy and emit large amounts of CO2. OEMs want to continue selling profitable D/E-segment models, and so converting to PHVs is effective for that purpose. Additionally, PHVs are entitled to "super credits," in which they are counted as more than one car at the time CO2 emissions are calculated. D/E-segment PHVs also allows the development costs to be added to their prices, and German OEMs are planning to aggressively launch D/E-segment PHVs because of this.

 Since many roads in Europe are designed for high speed driving, the diffusion of full hybrids other than plug-in hybrid systems is expected to be limited.

Optimum electric drive systems for each segment

E-MotorPower Vehicle segment CO2 Savings potential in NEDC
Electric Vehicle 50-90 kW 100%
Plug-in Hybrid 50-90 kW 50-75%
Full Hybrid 20-40 kW 20-30%
48V Mild Hybrid 5-15 kW -10%
12V Start-Stop <5kW 3-4%
Source: Continental
(Notes) 1. Dark colored cells (a ◎ mark is added when this page is printed) are forecasted to have strong demand.
2. This table reflects research done on the global market as a whole.



Advantages of the 48V mild hybrid system

 Continental's 48V mild hybrid system is the same as conventional hybrid systems in that the torque assist and recovery of braking energy during deceleration improve fuel efficiency. However, the price is lower in comparison with full hybrids (around EUR 1,000) which can lead to multiple advantages.

 Moreover, the use of a 48V power supply and motor opens up various possibilities. During actual driving, the system is allowed to do sufficient work as the auxiliary components are converted to 48V and the engine runs in an efficient condition, and HC emissions can be reduced during cold starts by heating the catalyst, among other examples. Equipping electrified superchargers is also expected to become popular.

Advantages of 48V Systems

Easy integration and low costs  Continental's 48 V belt starter generator (BSG) system, which is to be introduced in 2016, can be integrated into vehicles as a replacement for 12 V BSGs without major design changes.
 The 48V systems fills the large gap between current 12 V start-stop systems and expensive full hybrid systems. Moreover, the 48V system does not need the measures against electric shocks required by law for power supplies that are 60 volts and higher.
Enhanced recovery of braking energy  The 48 V system recovers braking energy with higher efficiency than 12 V systems. The recovered energy is stored in a more powerful lithium ion battery (has a capacity of 0.46 kWh).
Comfort during engine start-up  This enables a quick, quiet engine start.
48 V electric components  Continental considers high output air-conditioning compressors and highly efficient cooling pumps and oil pumps as candidates for 48V conversion. 12V power supplies will soon become insufficient to supply power to the air‐conditioning compressors, electric rolling stabilizers, and other electric components in large vehicles.
 Superchargers are also expected to be adopted. Although a 12V supercharger can work, conversion to 48V will mean offer full functional capability.

(Note) A characteristic of Continental's BSG system is the adoption of liquid cooling and an induction motor. The liquid-cooled system ensures high reliability, and unlike air-cooled systems, does not require the selection of an installation location. Moreover, using an induction motor is less costly because it has no permanent magnet.


The 48V systems support for the engine
Load point shift (gasoline engine)  The 48 V motor assists the engine when it is burning fuel at 2000-3000 rpm, which is a favorable combustion efficiency. This enables the engine to perform in higher load conditions during actual driving (this results in an improved actual fuel economy and reduced CO2 emissions).
Electrically heated catalyst (gasoline engine)  Cold start hydro carbon (HC) emissions are lowered 50% by heating the catalyst and reducing its light-off time. This is also demonstrated when idling for a long time or in coasting mode. Continental has already implemented this technology with the trademark of "EMICAT."
Emission control (diesel engine)  The motor reduces peak loads on the engine. This leads to the NOx reduction of 10% in the current NEDC test, and by 20% in the WLTC test, which will be used in Europe from 2017.

(Note) WLTC is an acronym for Worldwide Harmonized Light Duty Driving Test Cycle. A working group in the  United Nation's World Forum for Harmonization of Vehicle Regulations (WP.29) has been investigating a harmonized global standard for testing emissions and fuel economy since 2009. Japan is also considering the introduction of this new testing standard. The WLTC will reflect actual driving conditions more accurately than the current testing method.



Continental to begin producing Side-mounted type generators in 2020 and inline type in 2025

 The 48V mild hybrid system, which is to be introduced in 2016, has a structure that replaces the current 12V starter generator with a 48V one, and Continental says that this requires no major design changes on vehicles.

 Moreover, Continental jointly developed a prototype car (based on the Ford Focus 1.0-liter EcoBoost engine and six-speed manual transmission) with Schaeffler Technologies AG & Co. KG, which has a side mounted starter generator module that place the starter generator between the engine and transmission, and presented it in 2014 (it emulates a belt drive system). The prototype car lowered CO2 emissions by 17% from 114 g/km to 94.6 g/km, which raised the vehicle's level from Euro 5 to Euro 6. Mass production will start from around 2020.

 Continental is also developing an inline starter generator architecture, which phases out the belt and integrates a starter generator over the crankshaft axis, and is aims to start mass production from around 2025.


48 V system architectures Continental's three planned 48 V system architectures and respective fuel saving effects. The improvement of 13% is relative to the fuel economy of a vehicle without a start-stop system. (Photo: Continental) Side mounted Belt Starter Generator A side mounted belt starter generator module jointly exhibited by Continental and Schaeffler at IAA in September 2015. The starter generator is in the back left of the photo, and the drive axle and two clutches are in the right foreground. A belt connecting the components can be seen between them. (Photo: Continental)

Three 48V architectures

Production start Type Motor output Description
2016 Belt Starter Generator (BSG) 14kW  The existing belt driven alternator is replaced by a 48V starter generator. This replacement requires no major design changes for vehicles. The BSG system will remain as a model for emerging countries even after the launches of the following two variants.
2020 Side Mounted Starter Generator 19kW  Newly adding Schaeffler's electronic clutch (e-clutch), has made uncoupling the starter generator from the engine possible. This results in an increase in recovered braking energy, and improves fuel economy additional 5% in comparison to the original BSG system (a 18% reduction in total).
 The new electronic clutch automatically disengages the starter generator from the engine when the driver takes their foot off the accelerator pedal, and the vehicle enters coasting mode, which improve the fuel economy during high speed driving. In test runs Continental's prototype car was in coasting mode around 20% of the time.
2025 Inline Starter Generator 25kW  A motor is located on the crankshaft axis between the engine and transmission. A permanent magnet motor is used. Electrically-driven parking and creeping is made possible by disengaging the engine with the clutch. This model will be designed specifically for developed nations.
 Phasing out the belt does away with the friction loss it causes, and this offers the potential of a further 2% reduction in fuel consumption.


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