Campbell Scientific CSM1 Card Storage Module - Manual (Page 26)

Appendix C. Card Batteries
C-2
To optimize the life of the back-up battery:
a) Leave the card plugged into a powered-up CSM1 for as long as possible.
b) When using the cards at very high or low temperatures, try to return them
to a temperature close to room temperature as soon as they are unplugged
from the CSM1, e.g. in a very cold situation, unplug the card and transfer
it to the inside pocket of your coat.
c) When the card will not be used for long periods, remove the battery from
the card and store it separately.
C.2 Battery Status Detection
There are three levels of battery status detection. The exact detection is done
within the card itself; the status line only reflects the output from the card. The
exact battery voltage thresholds the card indicates vary with the card
manufacturer. The terminal voltage of the battery also varies with battery type
and with temperature. Therefore the exact capacity of battery available when
the level detector indicates the intermediate capacity (1 on the status line, LOW
with CSMCOM), is not fixed. In particular, at low temperatures where the
battery voltage is reduced, the LOW indication may be rather pessimistic.
The CSM1 only prevents data storage in the card when the card indicates the
battery is dead (0 on status line). If the card is being used at very low
temperatures and is almost exhausted, the dead indication may be given when
the card is still able to hold data. In an emergency, you may be able to continue
to use the card for a short period by warming the card, which will cause the
battery voltage to rise slightly, before placing it in the CSM1.
Some card types only measure the battery voltage when the card
is first powered up. The level of indication is then held in a latch.
Other cards monitor the battery voltage continuously. NOTE