SLUUB65B May 2015 – December 2022
In certain applications, it can be difficult to achieve traditional Qmax updates for systems with noisy standby currents that prohibit the dV/dt requirement from being met and whose total time in relax never reaches 5 hours, or for systems that rarely enter RELAXATION at all. The Fast Qmax feature provides a complement to traditional Qmax updates to more reliably account for aging effects in such systems by allowing Qmax updates to be achieved with only one or no qualified DOD points from a battery RELAXATION state. The feature is enabled via the Pack Configuration C [FastQmax] bit and uses several conditional checks to determine when fast Qmax-specific DOD point collection is allowed to start and when these are qualified for use in a fast Qmax update.
The Fast Qmax Update algorithm is not used during a learning cycle if Update Status ≠ 2.
The algorithm begins taking new discharge-based fast Qmax DOD points every 30 seconds once the following conditions are detected:
The algorithm qualifies and saves the discharge-based fast Qmax DOD point at the end of discharge when the following conditions are met:
The algorithm also qualifies and saves a charge-based fast Qmax DOD point 50 mV when full charge termination is achieved (that is, Flags()[FC] is set).
The Pack Configuration C [FastQmax] bit only controls enable/disable of DOD point collection in the near end of discharge region. DOD points at end of charge are always recorded for fast Qmax purposes.
As a result, it is possible to get fast Qmax updates with DOD points from relaxation, end of discharge, and end of charge. However, a fast Qmax update will not happen immediately upon end of charge, and will only be enforced if an attempt to record a new OCV has failed during battery relaxation following a full charge event. A Fast Qmax update is disqualified if:
Subclass ID | Subclass | Offset | Name | Data Type | Value | Unit | ||
---|---|---|---|---|---|---|---|---|
Min | Max | Default | ||||||
80 | IT Cfg | 39 | Fast Qmax Start DOD % | U1 | 0 | 100 | 92 | % |
41 | Fast Qmax Start Volt Delta | I2 | 0 | 4200 | 200 | mV | ||
43 | Fast Qmax Current Threshold | U2 | 0 | 1000 | 4 | HourRate | ||
40 | Fast Qmax End DOD % | U1 | 0 | 100 | 96 | % |