For Renault Zoe owners and EV enthusiasts diving into vehicle diagnostics, accessing data via the OBD2 port opens up a world of information about the car’s systems, especially the Battery Management System (BMS). Initial explorations often involve interpreting CAN bus data, and records like 0x445 are commonly assumed to hold crucial details about battery health, specifically the highest and lowest cell voltages. However, recent observations are challenging this straightforward interpretation, suggesting that the 0x445 data might not be as directly informative as initially believed for accurate battery monitoring.
Analyzing 0x445 CAN Records: Anomaly Detected in Voltage Readings
The expectation when examining 0x445 records is to find dynamic values that reflect the highest and lowest cell voltages within the Renault Zoe’s battery pack. This data is vital for ensuring optimal battery performance and preventing cell damage. However, analyzing captured 0x445 data reveals a peculiar pattern. Instead of consistent fluctuations that mirror real-time voltage changes across individual cells, the data sequence shows an initial shift in values followed by a prolonged period of unchanging records.
Consider this observed data sequence from CAN-filtered 0x445 records:
80, 57, aa, 73, ff, ff, 80
80, 55, f8, 73, ff, ff, 80
80, 55, f8, 73, ff, ff, 80
80, 55, f8, 73, ff, ff, 80
80, 55, f8, 73, ff, ff, 80
80, 55, f8, 73, 29, 8b, 80
80, 55, f8, 73, 29, 8b, 80
80, 55, f8, 73, 29, 8b, 80
80, 55, f8, 73, 29, 8b, 80
80, 55, f8, 73, 29, 8b, 80
80, 55, f8, 73, 29, 8b, 80
... and so on ...This data raises questions. If 0x445 truly represents highest and lowest cell voltages, why does the sequence stabilize after the initial records? In a functioning BMS, especially under varying conditions like charging or discharging, one would anticipate continuous updates reflecting cell voltage fluctuations. The observed static nature of these records, particularly when the vehicle is at rest with no load or charger connected, is unexpected.
Current Sensor Disconnection: A Confusing Factor Influencing 0x445 Data
Further complicating the interpretation of 0x445 data is the unexpected influence of the current sensor. It’s noted that disconnecting the current sensor leads to “ff” values appearing in bytes 4 and 5 (B4 and B5) of the 0x445 records. This observation is puzzling because the highest and lowest cell voltages are inherent properties of the battery pack itself, independent of whether a current sensor is connected or not.
Renault Zoe OBD2 port access for BMS data analysis, highlighting the area used to retrieve vehicle data including battery information.
The fact that disconnecting a component seemingly unrelated to voltage readings affects the 0x445 records casts doubt on the direct correlation between these records and solely the highest and lowest cell voltages. It suggests that 0x445 might encode information beyond just voltage extremes, or that the BMS data interpretation requires a more nuanced understanding.
Conclusion: Towards a Deeper Understanding of Renault Zoe BMS Data
The initial analysis of Renault Zoe Obd2 data, specifically the 0x445 records, reveals inconsistencies with the straightforward assumption that they directly represent highest and lowest cell voltages. The static data patterns and the unexpected influence of the current sensor indicate a more complex data structure or interpretation is needed.
Further investigation is crucial to accurately decode the information contained within 0x445 and other BMS related OBD2 data. This may involve correlating CAN data with direct cell voltage measurements, as initially planned in the observed research, to build a more comprehensive understanding of Renault Zoe BMS diagnostics and ensure accurate battery monitoring via the OBD2 port. Understanding these nuances is essential for both vehicle owners and the broader EV community interested in in-depth vehicle health monitoring and diagnostics.
