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Fiat Adding Bosch Stop-Start System to Fiat 500; Bosch Projects 50% of Euro New Vehicles to Have Stop-Start by 2012

A specially adapted starter and the engine control unit are the central components of the Bosch stop-start system. Click to enlarge.

Beginning in March 2009, Fiat will feature a Bosch start/stop system on the Fiat 500. (Earlier post.) Bosch supplies the specially adapted starter, the engine management system, and the battery sensor. Bosch has been manufacturing this start/stop technology since 2007, and has already delivered more than 500,000 starters to BMW and Mini. (Earlier post.)

In the Fiat 500, the system will initially be available in combination with the Dualogic automated manual transmission and a 1.2-liter engine. Fiat plans to install the system in other variants and models as early as 2009.

Bosch also supplies the engine control unit for the Fiat 500, including the software used to analyze all the relevant sensor data and to stop and start the engine. In addition, the battery sensor is also supplied by Bosch. It computes the current state of battery charge and relays this information to the energy management system.

In 2008, roughly five percent of all new vehicles in Europe are equipped with a start/stop system. By 2012, we estimate this will be every second newly registered vehicle—most of them with Bosch technology.

—Stefan Asenkerschbaumer, president of the Bosch Starter Motors and Generators division

In the next few months, series production of other cars featuring this Bosch technology is to start—the Kia cee’d, for example.

Test drives by Bosch engineers show that stop-start systems reduce fuel consumption, and thus also CO2 emissions, in the New European Driving Cycle (NEDC) by up to 5%. In the urban component of the NEDC, the saving can be as high as 8%. Stop-start systems automatically stop the engine when the vehicle is stationary, for example at traffic lights. The engine is restarted as soon as the driver depresses the clutch pedal to put the vehicle back into gear. As starter-based systems are largely based on existing components, their cost-benefit ratio is excellent. This approach is also suitable for cold starts in diesel engines.

Bosch has considerably increased the specified number of starts of the start/stop starter and as a consequence increased its service life compared with a conventional starter. Bosch strengthened the bearings subjected to heavy loading in the starter, and further improved the planetary gear. The commutator is optimized for longer life.

Next to the starter, the control software, and a battery sensor, the system as a whole includes a crankshaft sensor and the respective sensors at the pedals. A high efficiency alternator in combination with a deep-cycle resistant battery means that the amount of time the vehicle can remain stationary with the engine switched off is increased.



Great - bring it on - all cars should have this, especially diesels - to reduce pollution in urban areas as much as fuel and CO2 savings.

Then find a way of enabling a car to crawl through heavy traffic on battery alone - even < 20 KPH would help in very congested situations (like I see outside my door every morning).


How does it work with air conditioning?


How does it work with air conditioning?


How does it work with air conditioning?


"especially diesels" should read "especially spark ignition engines" since they consume 3 times more than diesels at idle.



"spark ignition engines" may consume 3 times more than diesels at idle, as you claim.

But what if diesel fumes and their micro/nano particles are 20 times more toxic?


Neil, turn on your car's ignition so that the engine is not running, but the battery is on. The A/C or heat will come on. Sure, if you do that for a long time, you will kill the battery, but for a short time, it will work. I assume these cars are equipped with sensors so that if one is stuck in traffic a particularly long time, the car will automatically start back up before juicing the battery completely.

I think this is a great idea and it should be on every car now. It would be great if we could get the cars to be able to inch forward in traffic without the ICE and without all the added complexity (and loss of trunk space) of a full hybrid.

This seems to be great for non-rush hour city driving (stop lights) but I don't ever take my car out of gear in bumper to bumper traffic (highway or city).


What you describe turns on the blower motor and neither the heat nor a/c will come on in any vehicle that uses the standard automotive heating and cooling systems (only newer full hybrids with all electric heating/cooling systems will operate as you describe and not anything that this stop/start system will be used on). You may, at best, get a minute or two of heat and probably less than that of cooling out of whatever is left from when you shut the vehicle off.

Henry Gibson

All air conditioning for cars should be done with electric compressors powered from the battery or alternator. All other pumps and fans in cars should also be electrically powered and all belts eliminated. The flywheel can now be the rotor of an integrated starter alternator. Larger lead batteries should be installed to both capture regeneration power and keep the airconditioning going while the engine is stopped. LG has a %40 more efficient free piston electric refrigerator compressor that can be adapted to cars.

Since nothing is mounted on the engine, welded sealed pipe can be used in the Ac system instead of hoses so there can be no leakage from a totally sealed system. for more than the life of a car.

Electric water pumps and radiator fans can also keep the car warm longer with the engine stopped and cool the engine at low speeds in traffic jams. Systems have long been developed to power the steering wheel and assisted brakes from electric motors.

The method of starting an engine with carefully positioned pistons and fuel injection and spark seem much more robust and certainly more novel. Henry For could have developed such a system for his Model T to save on much cranking. It would have only needed a few electric buttons and manual injectors.

Perhaps full electric valve control will allow a return to starting with compressed air but this time for cars not for diesel trucks. Eventually Scuderi may even build a prototype air hybrid engine. ..HG..

MG, it is a given nowadays that a diesel engine (which will have to conform to Euro 5) will have a DPF, in which case ... the comparable gasoline engine will be emitting more particulates!

In any case, idle is hardly the load condition in which either particulates or NOx are worst-case for a diesel engine.

Gasoline engines need stop/start more than diesel engines.

Regarding heating and A/C, when the weather is temperate, neither is a critical issue. Even the much-hallowed Prius keeps the engine running if the engine coolant temperature is too low ...

Brian P

sorry, above post was mine.

No, there is no way possible that Henry Ford would have been able to use Mazda's method of stop-start functionality in a daily driven vehicle. Even 40 years ago any auto manufacturer would have been hard pressed to do a reliable proof of concept in the labs. The technology probably could have been done as early as the mid 90's with OBD-IIs requiring more sensors and more powerful ECU controllers (thus opening the door for more careful engine monitoring) but it would likely have been unacceptable for mass appeal. Now the electronics are developed well enough and the customer base is more willing to accept a start-stop system.

The problem with converting everything to electric is one of power budgets and nothing more at this time. All electric pumps for everything from a/c, p/s and water pumps to brake assistance would increase vehicular efficiency but the modern cars 12 (14.4) volt system is overloaded as is. Convince customers to give up their 120W 8 speaker stereos, heated power seats, navigation systems, etc and you'd probably have enough left in your power budget to have everything run purely on electricity.


Not a fan, sorry
Half hearted compromise technology that removes the responsibility for best practice from the original vehicle design to the component supplier.It may well provide the claimed benefits in city driving but will certainly encourage a lazy attitude to design from the manufacturers.
The brake regeneration is compromised by (more) belt drive.
Do away with the starter completely and replace with large diam starter generator flywheel(clutch/ dual or torque converter) takeoff assist as seen on various European mild hybrid designs .
Reduced parts count 1 less belt and tensioner , reduced weight replace starter and alternator with higher powered electric assist. Better weight distribution, power handling ability.
Space saving and the ability to incorporate crank position sensors.


This is great news. I hope it spreads to all cars.

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