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2. HowTo replace batteries for S7-400

Why is a battery fault signaled when you insert a back-up battery, even though the battery is new?

Description:

With the S7-400 lithium (lithium/thionylchloride) batteries are used. In the case of lithium batteries with this technology a certain passivation film develops over long periods of storage which affects the immediate functioning of the battery. Under certain circumstances this can lead to an error message when the power supply unit is switched on. The power supply units of the S7-400 are able to clear the passivation film of the lithium battery through a defined loading of the battery. This process can take a few minutes. Once the passivation film has been cleared and the lithium battery has reached its rated voltage, you can acknowledge the error message of the power supply unit with the FMR button.

 

Since the storage time of the lithium battery is usually not known, we recommend the following procedure:

 

    Insert the backup battery(ies) in the battery compartment.

    Acknowledge any battery failure message from the power supply unit with the FMR button.

    If you cannot acknowledge the battery failure, wait a few minutes and try again.

    If you still cannot acknowledge the battery failure, remove the battery(ies) and short-circuit them for 1 to a maximum of 3 seconds.

    Replace the battery(ies) and try once again to acknowledge with the FMR button.

    When the display of the battery failure message goes off, the battery(ies) is(are) ready to operate.

    If the display of the battery failure message does not go off, the battery(ies) is(are) empty.