SLUUDA0A April 2026 – July 2026 BQ27Z855
SHELF mode operates the same as SHIP mode with a minimized amount of measurements and firmware processing. However, device power consumption in SHELF mode is reduced from SHIP mode by turning off the CHG and DSG FETs and hardware protector (all hardware-based protections and IWAKE). Due to the FETs being off in SHELF mode, the system is not powered without a charger attached, so the exit conditions are different from SHIP mode and the FET control logic is not performed.
In SHELF mode, the device measures voltage and temperature at periodic intervals and current is not measured or coulomb counted. Current is assumed to be and reported as 0 mA. The measurements performed each interval are:
Firmware processing is minimized by reducing the number of calculations. Some calculations are performed less frequently: only after voltage and temperature are measured. These less frequent calculations include updating firmware-based protections, lifetime data, and the voltage and temperature range of the advanced charge algorithm. Other calculations, such as updating RemainingCapacity() and FullChargeCapacity, are not performed at all with the assumption the system is off and will not communicate with the gauge.
SHELF mode is entered based on voltage through SLEEP or by command through NORMAL or SLEEP. Exit from this mode is through MAC SHELF_DISABLE (0x000c) or GPIO exit (when Ship Mode Config[IO_EXIT] = 1).
| Status | Condition | Action |
|---|---|---|
| Activate |
(OperationStatusA()[SLEEP] = 1 AND Voltage() < Power Shelf Mode Voltage Threshold for Power Shelf Mode Voltage Delay) OR (MAC SHELF_ENABLE (0x000b) received AND Power Ship Mode Command Delay elapsed AND |Current()| ≤ Sleep Current) |
OperationStatus()[SHIP] = 1 The device enters RELAX mode. Current() = 0 mA, AverageCurrent() = 0 mA The device wakes up every 60 s to measure voltage and temperature. The device does NOT coulomb count or measure current. Turn off the CHG and DSG FETs. Turn off the protector (all hardware-based protections and IWAKE). |
| Exit |
MAC SHELF_DISABLE (0x000c) received OR GPIO Settings GPIO Ship Exit pin grounded (when Ship Mode Config[IO_EXIT] = 1) |
OperationStatus()[SHIP] = 0 Return to NORMAL mode |
If the gauge is UNSEALED and the MAC SHELF_ENABLE (0x000b) command is sent twice in a row, the gauge enters SHELF mode immediately and skips the normal delay sequence.
The configuration options for SHELF are in the following data flash.
| Class | Subclass | Name | Type | Min | Max | Default | Unit | Description |
|---|---|---|---|---|---|---|---|---|
| Power | Shelf Mode | Voltage Threshold | I2 | 0 | 32767 | 2200 | mV | Cell based SHELF voltage trip threshold |
| Power | Shelf Mode | Voltage Delay | U2 | 0 | 255 | 10 | s | Cell based SHELF voltage trip delay |
| Power | Ship Mode | Command Delay | U1 | 0 | 255 | 0 | s | Delay to enter SHELF mode after MAC SHELF_ENABLE (0x000b) is received. This DF is shared with SHIP mode; see Power Ship Mode Command Delay in the SHIP Mode DF table. Send MAC 0x000b twice in UNSEALED mode to bypass delay and enter immediately. |