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Bosch Passes 1M Mark for Start-Stop Systems

In August 2009, the one millionth vehicle was fitted with a Bosch start-stop starter. (Earlier post.) In the New European Driving Cycle (NEDC), start-stop systems reduce fuel consumption, and thus CO2 emissions, by up to 5%. In the NEDC urban cycle, the saving is as much as 8%.

Elements of the Bosch Start-Stop system. Click to enlarge.

While only 5% of all new vehicles in Europe were equipped with this system in 2008, Bosch predicts that this share will increase to 50% by 2012. Bosch start-stop technology already features in models made by BMW and Mini, Fiat, Kia, and Volkswagen, among others.

Start-stop systems stop the combustion engine when the vehicle comes to a halt at a red light or in a traffic jam, starting it again automatically when the clutch is depressed and the vehicle is put back into gear. For this system, Bosch supplies a special starter, whose electric starter motor as well as low-noise, enhanced meshing mechanics provide safe, fast, and quiet engine starts.

The system also includes control software, which is generally integrated into the engine ECU, and a battery sensor, one of whose tasks is to record the current battery charge and relay this information to the energy management system. This ensures that the engine is only stopped if the battery has stored enough energy to start the engine again quickly. The system is rounded off by a crankshaft sensor, sensors on the pedals, and a deep-cycle resistant battery.

For start-stop operation that is as uninterrupted as possible, Bosch also offers a new series of alternators. In the models of the “Efficiency Line” (EL) series, Bosch engineers have improved the electrical design and used new diodes, and in this way achieved an efficiency of as much as 77%. In addition, these alternators ensure that the battery is well-charged even when the engine is idling or running at low revolutions. A well-charged battery is a condition for start-stop. The combination of Bosch EL alternator and start-stop system can reduce fuel consumption (and thus also CO2 emissions) in urban driving by as much as 10%.



Anyone got any idea what the specs are for these deep cycle resistant batteries?
Are they using lead acid or NiMH?
The Merc is the first to use lithium, so the others can't be using that.


Some car makers, like BMW and Rover (for LandRover) used recently "Absorbed glass mat (AGM) batteries" for their Stop-Start systems. You can search for their specs. I didn't see that some maker used other chemystries just for that purpose. E-Motor used in the Merc is much more powerful (~15 kW) than these ISGs for just Stop-Start purpose.


I would hope they could evolve the stop-start system into a stop-start/crawl system where it can crawl the car through heavy traffic, initially < 10 mph.

Then as batteries and the technology in general improve, the top "crawl" speed can be increased to 20, 30 and maybe 40 mph.

They you have evolved from a mild hybrid into a full hybrid in a planned manner.

This would be particulily useful for diesels which cause pollution in urban areas.

Henry Gibson

Yes crawl tecnology!!! The integrated flywheel alternator-starter has been known for years??? ..HG..

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