When the battery light in the car starts flashing, it is not a good sign, and that’s the way it has been for decades. Sensors measure current flow, voltage and temperature of the car battery, and indicate when the critical level approaches. Therefore, traditional battery sensors have long been indispensable in battery management in cars – even though the classic state of charge (SoC) measurement is not always very accurate. This is due to its somewhat faulty measuring method, which is based on cell voltage and internal resistance, as at least older persons may know from their own experience.
However, in recent years, ever more sophisticated and complex sensors have provided increasingly more accurate solutions in battery technology. In combination with ever smaller controllers, communication boards and wireless transmission options, they enable the realization of ever more powerful battery management systems (BMS). These enable countless new, safe and customer-friendly applications to be realized at low additional cost and in the smallest space.
While temperature sensors for preventing overheating have long become state-of-the-art in battery solutions, new, completely individual sensor solutions are now being added. For example, the Swiss company Tefag Elektronik recently announced a device that works with sensors for pressure monitoring of battery cells that will be used in a vacuum. More information about this will be available at electronica in November.
Motion sensors are now also increasingly being used in battery solutions. With the sleep sensor function in solutions from Ansmann, these prevent garden tools from discharging themselves and losing capacity during a period of hibernation. There is also a snooze mode that only reduces standby power consumption. Tefag Elektronik uses a similar technology to bring the batteries of defibrillators through the often long sales and storage times until their first use.
The market is observing contrary trends when it comes to the topic of standard monitoring. Especially in view of the continually increasing safety requirements, temperature self-monitoring of the battery, for example in medical technology, is becoming increasingly important and temperature sensors are therefore often used on every cell in multi-cell battery solutions. This applies not only to medical and safety technology. Tefag Elektronik customers have also decided in favor of such a one-to-one coverage solution for energy systems of transport vehicles in the logistics sector, which are used 24/7 in fully automated operation under demanding conditions, according to the company.
In contrast, engineers at the Ruhr University Bochum, Germany are working on a contrary concept for electric cars. The battery of an electric car consists of individual blocks, each containing up to twelve cells. Instead of monitoring each of these cells with its own voltage sensor, the goal of the team there is to get by with a single voltage sensor. “Besides the cells, the sensors are a major weight and also cost driver,” explains Philip Dost, Research Assistant Power Systems Technology and Power Mechatronics, at the Ruhr University Bochum, the relevance of the topic sensor technology for battery management. However, so the objection of other experts, in case of doubt, the question of safety must first of all be clarified.
Engineers working on charging technology for the automotive sector, such as Deutronic, announce new adaptive charging and monitoring algorithms with dynamic adaptation to a wide variety of batteries and consumption situations.
Also new is the way in which warnings or also sensor data are output from the battery. Ansmann has taken on a pioneering role here. The warning light has become increasingly obsolete. In some cases, it is even replaced by an app. At electronica 2018, Ansmann will once again be presenting new applications for its standardized, cost-effective intelligent battery systems for networking and monitoring rechargeable, mobile battery systems for logistics vehicles and systems. With its standard integrated Bluetooth communication interfaces, the intelligent battery system reports any system data of its battery pack or packs to a fixed or mobile third-party device via Bluetooth. In the basic version of the app, the power still available, number of charging cycles and battery wear are remotely monitored and reported. Further functions are integrated according to customer requirements.
The system is already being used successfully by several electric scooter and electric bike fleets in commercial delivery service, and bike rental for monitoring and maintenance of the bikes. “Safety is still the top priority in battery management. We quite rightly have an excellent reputation here,” emphasizes Thilo Hack, Head of Industrial Solutions at Ansmann. “Furthermore, however, we are now able to offer outstanding, service-oriented solutions with little effort, in particular, for the fleet management segment. These solutions help customers to work efficiently with their ever-increasing number of mobile devices and vehicles. This is a new, multi-facetted field with great potential.”