Anatomy of a “mild hybrid”

New high-voltage “mild hybrids” – which use 48-volt batteries – cut both fuel consumption and emissions by boosting acceleration with electric power following Stop/Start, and using regenerative braking

1 Hybrid controller Manages Stop/Start and tells electric motor/ generator when to charge battery or accelerate car

2 Battery controller

3 448-volt battery Lithium-ion. Charges or discharges at each Stop/Start cycle

4 AC/DC converter  Changes AC generator current to DC for battery

5 Electric motor/ generator: Starts engine. Drive belt connects to crankshaft to boost torque.
Charges battery during braking

6 Electric supercharger 48-volt turbine forces extra air into engine when spurt of power is needed

7 DC/DC converter Steps down 48-volt power for 12-volt accessories such as climate control,
sat-nav, gadgets

8 12-volt battery Conventional lead-acid battery

Power distribution centres

Engine

Global CO2 emissions

35.7 billion tonnes carbon dioxide (2014)

18.2% Manufacturing and construction

4.6% Other energy industries

15.7% Other

3.3% Shipping

1.9% Aviation

21.3% Road

35.0% Electricity, heat

Auto emissions targets (grams CO2 per km)

Mexico 145 2016

Brazil 138 2017

Japan 122 2020

China 117 2020

India 113 2021

South Korea 97 2020

U.S. 97 2025

Canada 97 2025 

EU 95 2021

Sources: Delph Automotive, Ricardo, European Commission