Siemens S7-400 Installation Manual page 166

Starting Up
Reducing the Passivation Layer
Lithium batteries (lithium/thionyl chloride) are used as backup batteries for the
S7-400. In lithium batteries of this technology, a passivation layer can develop after
storage for a very long time, and the immediate functional capability of the battery
may not be certain. This may result in an error message when the power supply
module is switched on.
The power supply modules of the S7-400 are capable of reducing the passivation
layer of the lithium battery with a defined load on the battery. This process may
take some minutes. When the passivation layer has been reduced and the lithium
battery has reached its rated voltage, the error message of the power supply
module can be acknowledged with the FMR button.
Since the storage time of the lithium battery is not usually known, we recommend
the following procedure:
• Insert the backup battery/batteries in the battery compartment.
• Acknowledge any battery error message of the power supply module with the
FMR button.
• If the battery error cannot be cleared, try again after a few minutes.
• If the battery error still cannot be cleared, remove the battery/batteries and
short-circuit it/them for one to three seconds maximum.
• Reinsert the battery/batteries and try to acknowledge with the FMR button
again.
• If the battery error message goes off, the battery/batteries is/are operational.
• If the battery error message does not go off, the battery/batteries is/are
discharged.
Removing a Backup Battery
Chapter 7 describes how to remove the backup battery (batteries).
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S7-400 and M7-400 Programmable Controllers Hardware and Installation
A5E00069481-04