State of Charge Calculation with Dynamic Drift
The Orion BMS calculates the state of charge of the battery primarily by tracking the current going in and out of the battery, a technique commonly referred to as coulomb counting.
While this method is accurate, no system is ever perfect. Because of this, the Orion BMS uses settings from the battery profile to look for discrepancies between the calculated state of charge (based on voltage) and the measured state of charge (based on coulomb counting). When differences are found, the BMS will cause the calculated state of charge to “drift” towards the correct state of charge.
Some other BMS systems correct the state-of-charge instantly rather than drifting. While that may not seem like a problem, often times external systems are monitoring the state of charge of the battery and are basing decisions on that number. An SOC drift allows for the state of charge to be adjusted over time, gives advanced warning to other systems, and avoids oscillations.