Tuesday, July 14, 2015

Bosch's 48V mild hybrid system to debut this year

With so many innovative vehicle concepts testing the market we almost forget that most vehicles sold are still traditional gasoline vehicles. Such vehicles can be made more fuel-efficient by adding a mild hybrid system.

A new trend in the development of mild hybrid systems has been the use of 48 Volt lithium-ion batteries. These batteries replace lower voltage systems, often using 12V lead-acid batteries (or occasionally even nickel-metal hydride (NiMH) batteries). This has been made possible by advances and cost savings in li-ion technology. According to Just-Auto a 48V architecture provides about four times the energy recuperation from regenerative braking than is available on the traditional 12V system. Full hybrids use much higher voltages, for instance the Toyota Prius hybrid synergy drive uses a 220V battery.

Many automotive suppliers have jumped on the band-wagon, including Continental, Johnson Controls and Bosch.

Automotive news Europe interviewed Bosch executives about this subject recently. In 2013, GS Yuasa, Bosch and trading house Mitsubishi Corp. formed a joint venture to develop low-cost, high energy-density lithium ion batteries by 2020. A Bosch executive told Automotive news that they are "on a good path" toward their goal of developing a lithium ion battery that costs half as much as today's batteries but has twice the energy density.
Such advances will greatly popularize the use of hybrid and electric-only drive trains. Bosch expects such drive trains to account for 15 percent of the global automotive market by 2020. Mild hybrids are expected to break through with the introduction of 48V technology and could account for most of those vehicles.

Bosch also is rolling out a new 48 V mild-hybrid system this year that it says will improve fuel efficiency at minimal extra cost. Bosch has named its system "Boost Recuperation System" (BRS) which features an electric motor, with a 48V 0.25kWh lithium-ion battery and DC/DC converter. The system potentially reduces fuel consumption by 5 to 18%.

BRS offers four functions:
- coasting
- start-stop
- recuperation
- torque boost
When coasting and during start-stop the 48V battery keeps the car's electronics and climate control running. Recuperation enables the car to recover braking energy. The battery can provide the vehicle a torque boost of up to 10 kW. 
Bosch's system debuts this year in a nameplate for Europe offered by a European automaker, executives said. They declined to name the customer. Bosch aims to sell the mild hybrid system in other markets, including North America.