Originally published on EV Tech Expo.
This post has been kindly sponsored by The Electric & Hybrid Vehicle Technology Conference.
By Daniel Kok, PhD
In June this year, car manufacturer Mercedes-Benz announced that it will introduce 48V mild-hybrid battery technology across its prestigious S-Class range in the next few years. The German giant is the latest in a long list of manufacturers keen to embrace 48V systems, with the mild-hybrid market set to grow to more than $250bn by 2031.
The need for fuel-efficient technologies such 48V vehicle systems is evident. US President Barack Obama has set an ambitious CO2 emission target of 70-80g/km by 2025, putting pressure on US manufacturers to come up with solutions quickly. In Europe, the European Union-led global CO2 emission target could be as low as 60-70g/km by 2030.
It’s clear that 48V technology will have a role to play in achieving these targets, but the modest efficiency gains – typically a 5-10% fuel consumption saving in real-world conditions – are less than those of full hybrids or electric vehicles.
The relative simplicity of adopting 48V systems within existing vehicle designs and the low cost of integration make the technology attractive for manufacturers, but greater opportunities exist than simply additional support for a vehicle’s powertrain. To take full advantage of the increased opportunity of 48V, designers will have to optimize the vehicle’s electrical architecture.
“The peak power draw from chassis and comfort systems can coincide with the peak power draw from the powertrain system,” says Daniel Kok, who manages Advanced Electrified Powertrain Systems at Ford Motor Company in Michigan. “In the end, the total power capability of the 48V system is often limited by what the [typically lithium-ion] battery can provide.”
In June this year, Alistair Davidson of the Advanced Diesel-Electric Powertrain (ADEPT) consortium, claimed that “lead-carbon batteries are the most cost-efficient way of meeting stringent future CO2 emission targets.” The team’s so-called intelligent electrification of a Ford Focus can deliver the fuel efficiency and C02 reduction of a full hybrid-diesel powertrain, all at reduced cost.
The emerging industry is developing quickly, but because some manufacturers want to develop their own proprietary solutions, it is at risk of fragmentation, leading to calls for the development of a set of international standards. In 2014, Audi, BMW, Daimler, Porsche and Volkswagen proposed the LV 148 standard to define a 48V power supply including its functions and interfaces, but enthusiasm for it has been muted as organizations seek to develop their own solutions.
The argument for an international standard is that it would help improve collaboration between the automotive industry and suppliers, thereby unlocking significant economies of scale. The issue is an increasingly important one as the industry gears up to meet the more stringent Worldwide harmonized Light vehicles Test Procedures (WLTP).
To more closely mimic real-world driving conditions, the new test will see the C02 effect of stop-start systems reduced by 50%, posing a significant challenge for the industry. Working under a common standard could speed up the development process, but in a competitive market that might be difficult to achieve.
In a world still reeling from the emissions scandals of the past year, the standard could go some way to helping re-establish consumer faith in the opportunity and ability for mild-hybrid technology.
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