TECH FOCUSMake Battery Health a Part of your Business
TROY, MI - Delphi recently introduced the IVT battery sensor to provide fuel economy and battery performance, measure elements of battery health and extend battery life. Key to an active energy management system, the sensor is able to precisely measure the three parameters essential to calculation of battery health: current (I), voltage (V) and temperature (T).
Today's typical vehicle is not able to measure battery charging and discharge current. There are few vehicles that claim to measure these parameters, and most that do lack the measurement accuracy and range of the IVT sensor.
Tri-State BasicsAccurate measurements of three battery states (current, voltage and temperature) enable the active energy management system to control battery charging and manage vehicle electrical loads, optimizing vehicle performance. State of Charge (SOC) is a measurement of the battery's charge level versus its capacity. It is calculated as a percentage of the battery's overall charge capacity. SOC is determined by monitoring the amount of current over time that is added to (charging) or taken from (discharging) the battery. During vehicle off cycles, battery voltage and electrolyte temperature also are used to verify SOC. When the SOC is sufficient, the alternator output voltage can be lowered to a level that maintains the charge. Decreasing this load on the alternator in turn lowers the engine's mechanical load, improving fuel economy up to 0.5 mpg. According to the Battery Council International, automotive batteries have an average life of 41 months. Premature battery failure is most often caused by rundown or deep discharge. SOC monitoring detects an energy drain so that the load control system can shut down the load, helping prevent rundown. State of Health (SOH) is a "measurement" of a battery's ability to deliver specified performance compared to a fresh battery. It takes into account the capacity, charge acceptance, internal resistance (power capability) and self-discharge. In addition, it is a measure of the useful lifetime consumed and amount remaining before replacement is required. Monitoring SOH allows the customer to schedule necessary service events such as battery replacement."The traditional methods for measuring battery current, voltage and temperature do not provide the level of accuracy and resolution necessary to provide meaningful inputs for optimum energy management," says Rob DeAnna, strategic business planner for Delphi.
This information is required by the active energy management system to control battery charging and manage vehicle electrical loads. This information is ever more critical as electrical content on vehicles increases, and batteries and alternators are called upon to work harder.
"This trend drives the need for more efficient energy management, which involves the balance of power generated, stored and required for vehicle start-up at all times," says John Kirk, Delphi sensor development engineer.
The active IVT
Available for the 2010 model-year platform, the IVT sensor will be able to collect the data required for calculating the three elements of battery health. This new sensor rolls a lot of benefits into one small package that incorporates electronic advances without sacrificing performance or efficiency.
Some key benefits of integrating the IVT sensor in an electrical/electronic system include:
* Improved fuel economy by reducing the alternator load when the battery is fully charged.
* Extended battery life by maintaining the battery at an optimal charge level.
* Ability to optimize battery and alternator size. Non-equipped vehicles require excess energy storage capacities (larger batteries) and high current charging systems (large alternators) to address marginal operating conditions, whereas a battery-managed system maintains a high State of Charge (SOC), permitting a smaller-sized battery and alternator to be used.
* Maintenance of engine crank reserve. Managed loads preserve a minimal acceptable charge.
* Continuous availability of safety critical functions, such as when an active system shuts down non-critical loads and alerts the driver of the condition.
* Extension of incandescent bulb life by operating at a lower average voltage.
* Helps vehicle manufacturers keep up with the electronic demands of new vehicle content.
Performance SpecificationsRangeAccuracyCurrentLow+/- 1A+/- 10mAOperating+/- 300Alarger of +/- 1% of reading
or +/- 80mAStarting-1200A to 300Alarger of +/- 3% of reading or +/- 400mAVoltage6V to 18V+/- 30mVTemperature-40°C to 85°C+/- 2°CTable source: Delphi Corp. 
