SLUUB65B May 2015 – December 2022
Full charge termination is detected on the basis of voltage-, current-, and capacity-based conditions or SOC level, depending on the setting configured in FC Set %.
FC Set % | Termination Criteria |
---|---|
–1 | FC bit is set based on charge termination detection with current/voltage. |
Any other value | FC bit is set based on StateofCharge(). |
AverageCurrent() is not used for the qualification because its time constant is not the same as the Current Taper Window. Two current qualifications are done to prevent false current taper qualifications. False primary charge terminations happen with pulse charging and with random starting and stopping of the charge current. This is particularly critical at the beginning or end of the qualification period.
It is important to note that as the Current Taper Window value is increased, the current range in the second requirement for primary charge termination is lowered. If the Current Taper Window is increased, then the current used to integrate to the Min Taper Capacity is decreased and this threshold becomes more sensitive.
Once full charge termination conditions are met, the Flags()[FC] bit is set to indicate charge termination to the host. Additionally, if Pack Configuration [RMFCC] = 1, then RemainingCapacity() is set equal to FullChargeCapacity() upon full charge termination. The fuel gauge exits charge termination and associated flags are cleared when SOC decreases below FC Clear %. FC Clear % sets a StateOfCharge() percentage threshold at which the Flags() [FC] bit is cleared.
The gauge also records voltage at charge termination and stores it in V at Chg Term. It is used by the gauge to learn the depth of discharge (DoD) of a full battery for a given system. This is updated by the gauge after every charge termination to account for variations between systems and different temperatures.
V at Chg Term defaults to 4200 mV but can be initialized to the nominal charging voltage of the system.
FC Set % and FC Clear % only affects the Flags() [FC] bit, which does not affect the charge termination process.
Subclass ID | Subclass | Offset | Name | Data Type | Value | Unit | ||
---|---|---|---|---|---|---|---|---|
Min | Max | Default | ||||||
34 | Charge | 0 | Charging Voltage | I2 | 4000 | 5000 | 4350 | mV |
36 | Charge Termination | 0 | Taper Current | I2 | 0 | 1000 | 100 | mA |
2 | Min Taper Capacity | I2 | 0 | 1000 | 25 | mAh | ||
4 | Taper Voltage | I2 | 0 | 1000 | 100 | mV | ||
6 | Current Taper Window | U1 | 0 | 60 | 40 | s | ||
9 | FC Set % | I1 | –1 | 100 | –1 | Percent | ||
10 | FC Clear % | I1 | –1 | 100 | 98 | Percent | ||
82 | State | 3 | V at Chg Term | I2 | 0 | 5000 | 4350 | mV |
The CHG bit in the Flags register is used to indicate when charging is complete.
[CHG] bit is cleared:
[CHG] bit is set:
TCA Set % and TCA Clear % only affect the Flags() [CHG] bit, but does not affect the charge termination process or the gauging function.
Subclass ID | Subclass | Offset | Name | Data Type | Value | Unit | ||
---|---|---|---|---|---|---|---|---|
Min | Max | Default | ||||||
36 | Charge Termination | 7 | TCA Set % | I1 | –1 | 100 | –1 | Percent |
8 | TCA Clear % | I1 | –1 | 100 | 98 | Percent |