Trelleborg is helping the automotive industry mitigate battery issues inherent in stop-start systems with a small but ingenious valve seal.
Stop-start vehicle systems are gaining popularity in the automotive industry for their role in increasing fuel economy and at the same time reducing environmental impact. The systems use a type of lead acid battery known as Absorbent Glass Mat (AGM), which incorporates a glass mat that absorbs and holds the acid while separating the positive and negative plates. This battery has many attributes, including long life and vibration resistance as well as being totally sealed and virtually spill-proof, maintenance-free and fully recyclable.
Start-stop vehicle technology puts a lot of strain on the battery because while the engine is off, the battery is the sole source of power to all the car’s electrical devices, such as the air conditioning, radio and navigation system. In advanced start-stop systems, which incorporate regenerative braking or passive boost, there is further stress to the battery. A key to the proper function of AGM batteries is the ability to release pressure from minor gassing that occurs during charging. This can lead to explosive fumes and degradation of battery performance.
To deal effectively with this issue, Trelleborg has developed the Ventseal Light, a patented design that is a combined seal and pressure-controlled valve. The valve deals with low pressure buildup and opens between pressures of 50 to 400 mbar, depending on the application. Once the pressure is released the device closes automatically to prevent leakage from the battery. Although it is a tiny component compared with the size of the battery, this critical part must provide reliable sealing throughout the life of the battery and operate at extreme temperatures. The valve allows for a high rate of charge and discharge, something that happens when the engine switches on and off to save on fuel consumption. With increased punitive legislation related to fuel consumption, stop-start systems have become more attractive, as they can save between 2 and 10 percent on fuel consumption.
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