Siemens Simatic M7-400 Reference Manual page 41

Storing Backup Batteries
Backup batteries must be stored in a cool, dry place. The maximum storage time is
10 years.
Warning
!
Improper handling of backup batteries can cause injury and material damage. If
backup batteries are not treated properly, they can explode and cause severe
burning.
Please observe the following rules when handling backup batteries used in the
S7-400/M7-400 programmable controllers:
•
never charge them
•
never heat them
•
never throw them in the fire
•
never damage them mechanically (drill, squeeze, etc.)
S7-400, M7-400 Programmable Controllers Module Specifications
A5E00069467-07
General Technical Specifications
1-13