Friday, June 1st 2012
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Start stop systems

Technology update June 2012

Moditech's vehicle technology experts are constantly reviewing and evaluating new vehicle technology information to keep the Crash Recovery System vehicle database up to date. For this reason, they are able to see trends within the automotive industry in the early stages. One such trend that is emerging is the widespread introduction of start/stop systems in new vehicles, especially for the European market.


How does this affect emergency response? Find out in our technology update!


Start-stop systems automatically shut down and restart the internal combustion engine to reduce fuel consumption and emissions, for instance when the vehicle stops at a traffic light. To engage an auto-stop the driver needs to put the transmission to idle and release the clutch. As soon as he steps on the clutch again, the engine will restart and the vehicle can continue driving. The start-stop system is only operational if certain parameters are correct, such as a sufficiently charged battery and the right operating temperature of the engine.

This is nothing new or groundbreaking, nor does it have any real affect vehicle accidents. Nevertheless, it is possible that as systems and components change in vehicles equipped with start-stop systems, there may still be changes to certain rescue-relevant vehicle components. The biggest concern is that this frequent starting of the vehicle's engine will affect the occupant's comfort. An example of this would be because of the increased energy requirement during the restart; it may prevent the radio from working for a short period of time. When the normal 12-volt battery cannot supply the required energy, the car manufacturers can choose from two (2) options:


The increased energy demand can be covered by adding an additional battery. This battery will not necessarily be the same size as a conventional battery. Some manufacturers rely on a much smaller auxiliary battery that can be placed in areas of the vehicle that are more difficult to access (such as thefoot well area). Vehicle manufacturers recommend that emergency responders should always disconnect all batteries in the vehicle to shut down the vehicle's electrical system. This is why theCrash Recovery System shows all possible battery locations for a specific model, and guides the user to these batteries and indicates which battery is the main battery.



As an alternative, some manufacturers use an ultra-capacitor as the energy storage device to restart the engine. This design, known as E-Booster, covers the high-energy demand needed when restarting a diesel engine. Ultra-capacitors are able to store a hundred times more energy than a conventional capacitor and at least ten times more than a 12 volt battery with a high service life of a million charge cycles.

The problem with such ultra-capacitors is not the electrical danger as they operate with only 5.2 volts but the potential damage to the capacitor in the event of a collision or during extrication activities as these capacitors contain the chemical acetonitrile as a solvent. Acetonitrile is highly flammable and harmful by inhalation, ingestion, and/or skin contact.


Emergency responders should need to exercise caution not to damage an ultra-capacitor while working on a vehicle with rescue tools. On vehicles currently available with this technology (Peugeot and Citroen vehicles with e-HDI engines) the ultra-capacitor is mounted in the left front fender area. The position of these capacitors, as well as some background information, has now been added to theCrash Recovery System. If an existing ultra-capacitor has been damaged in the accident, responders should take extra precautions when working in close proximity the device. The manufacturer of the capacitor and of the vehicles advice responders to wear full personal protective equipment, includingrespiratory protection.