SLUUB65B May 2015 – December 2022
The fuel gauge can indicate detection of slow developing shorts, or micro shorts, within the battery if the [SE_ISD] bit in Pack Configuration B is set. The gauge compares the self-discharge current calculated based on RELAXATION mode to the AverageCurrent() measured in the system. The self-discharge rate is measured at 1-hour intervals. When battery SelfDischargeCurrent() is less than the predefined –Design Capacity/ISD Current threshold, the [ISD] of Flags() is set high. The [ISD] of Flags() can be configured to control interrupt pin (HDQ or SE) by enabling the INTERRUPT mode.
It is recommended to test this feature and tune ISD Current to obtain the optimal value to avoid both false positives and false negatives.
To help avoid false positives, a filtering the amount of change allowed in SelfDischargeCurrent() register is possible. A large value of ISD I Filter restricts large fluctuations in the value of SelfDischargeCurrent() if the most recent current value read by the gauge is significantly different from the previous readings. A small value of ISD I Filter allows the value of SelfDischargeCurrent() to update to a value that is closer to the most recent value read by the gauge. The SelfDischargeCurrent() is most accurate when the load on the gauge has been completely removed. The Min ISD Time parameter defines the amount of time(hrs) the gauge needs to wait after the initial DOD measurement is made in RELAXATION mode before comparing SelfDischargeCurrent() to the computed threshold.
Subclass ID | Subclass | Offset | Name | Data Type | Value | Unit | ||
---|---|---|---|---|---|---|---|---|
Min | Max | Default | ||||||
48 | Data | 19 | ISD Current | U2 | 1 | 32767 | 10 | Hour Rate |
48 | Data | 21 | ISD I Filter | U1 | 0 | 255 | 127 | Count |
48 | Data | 22 | Min ISD Time | U1 | 0 | 255 | 7 | Hour |
The [ISD] flag can be configured to control an interrupt pin (SE or HDQ) by enabling INTERRUPT mode. See Section 6.3, INTERRUPT Mode, for details.