Verifying Battery Ship Mode Entry and Wake Up

A ship mode command can reduce standby drain only if the system actually enters the intended state and avoids unintended wake events. The same design must also provide a reliable way to leave that state after storage. Verify entry, retention, and wake up as one sequence.

Read the supported state transitions

Identify the required input power condition, control pin states, register settings, and wake sources. The TI BQ25120A data sheet describes ship mode behavior and wake mechanisms involving input power and the manual reset interface. The exact entry and exit rules are device specific.

Record which registers and output states are retained or reset. A processor may restart with defaults that differ from the configuration used before ship mode, so the first firmware actions after wake belong in the review.

Measure total stored current

Measure battery current after the device has completed entry and relevant capacitors have settled. Include every circuit attached directly to the battery, not only the current through the switched system output. Protection, monitoring, pullups, and test connections can dominate a low current state.

Check the measurement instrument’s range changes and burden voltage. An autoranging meter can disturb a low power circuit or miss a brief wake pulse. Use a method appropriate to both the steady current and transient behavior.

Inspect potential wake inputs

Verify button polarity, required duration, release behavior, and any configurable interpretation. Test a short press, a valid press, a held button, and contact bounce according to the supported interface. Include input source attachment and removal. Repeat with the button already held when input power arrives.

Check that floating signals, leakage, or an external accessory cannot keep a wake input in an unintended state. Do not add a pull resistor without reviewing its own storage current and the pin’s documented electrical requirements.

Verify the first usable operation

Observe battery voltage, system rail, reset, and the wake signal from the initial event through successful firmware startup. Test the battery voltage range over which wake is required, within the approved operating limits. A status pin transition alone does not establish that the processor and peripherals started correctly.

Save entry commands, pin states, current measurements, wake timing, and initialization behavior. Repeat the sequence enough to expose state dependent failures and include a full power cycle as a separate case. A useful ship mode validation demonstrates a bounded storage drain and deterministic recovery, rather than merely showing that the main output turns off once.