Quantifying Transient Resistance Measurement Errors Driven by Data Acquisition Delay
Data acquisition delay inflates cell transient resistance measurements by capturing double-layer charging decay rather than pure ohmic voltage drops.
Multiplexed Sampling
Meaning
Sequential measurement techniques allow a single processor to monitor multiple input channels by switching between them at high speeds. Using multiplexed sampling reduces the hardware complexity and cost of a large battery management system. It relies on a switch to connect each cell in a series to a central converter.
Switching Mechanism
Electronic gates open and close in a predefined order to route signals to the measuring device. During multiplexed sampling, the system captures one channel at a time, creating a small time offset between the first and last reading. This staggered approach is effective for slowly changing variables like temperature.
Signal Skew
Discrepancies arise when high frequency events occur across different cells simultaneously. Because multiplexed sampling cannot read every cell at the exact same instant, the resulting data set may show a phase shift that does not exist in the physical pack. Software algorithms must compensate for this timing error during high power transients.
Economic Priority
Implementation of this method is driven by the need to balance performance with the expense of the monitoring electronics. A system utilizing multiplexed sampling requires fewer analog to digital converters than a parallel architecture. This choice lowers the total part count for mass produced electric vehicle battery packs.