From March 2018, all new car models in the EU will require eCall technology that can automatically communicate with the 112-based emergency response service in the event of an accident.
This is a safety critical system with a direct impact on life and death.
The eCall system is a module within the vehicle with GPS and a mobile communications function to alert emergency services if the vehicle detects a collision. Vehicles will also include a manual option to give the driver or passengers extra security if required.
eCall modules are therefore required to offer a fail safe solution at all times and in any condition.
In the event of an accident, there will always be the potential for the main power source in a vehicle to be disabled or disconnected, making the requirement for a secure, independent power source to be fully functional.
The basic requirements for the back-up battery must be able to:
- Hold sufficient charge to power a voice call for up to 15 minutes.
- Discharge stored energy at anytime that the vehicle is in motion. In European GSM networks, a voice communications system must be capable of supplying peak loads of up to 2.5A.
- Have the potential to last the lifetime of the vehicle.
To add to this, any engineers must also consider external conditions trying to encompass as many potential environments from around the world as possible. This can include minus temperatures in freezing conditions to extreme heat from prolonged exposure to direct sunlight (paying serious attention to the location on the vehicle).
The above can rule out Primary (non-rechargeable batteries).
A suitable candidate for this power source is NiMH which is stable over time and more extreme temperatures than Lithium-ion offering the reliability and longevity that is required from manufacturers.
However, it should be noted that conventional NiMH batteries are typically rated for operation at up to +65°C.
To support this market, Varta Microbattery GmbH have introduced the V...HRT Powerful range of NiMH button cells.
This is a family of high rate, and high temperature cells functioning from -20°C to +85°C.
At extreme low temperatures, the solution to the problem is not only internal to the cell, but helped by external innovationals also. VARTA Microbattery has implemented a foil heater which is affixed directly to the flat surface of the cell. Driven by power from the vehicle’s battery, which is guaranteed to be available up to the point at which the vehicle is in a collision, this foil heater can heat the cell from -40°C to 0°C in less than 10 minutes.
Application_Note_eCall_en.pdf 144.9 KB