CareFusion MicroDL, Operating Manual

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Battery Management
There are two sources of internal battery power in the MicroDL.
The recorded data is stored in a battery-backed memory, supplied
by a Lithium power source with an expected life of at least 10 years.
This battery also supplies the timekeeping clock.
The microcomputer circuitry is supplied by a 9 volt, alkaline PP3
battery. The battery life is approximately 24 hours of continuous
use.
The battery voltage is monitored continuously and the following
warning message is displayed when the battery starts to become
exhausted:
The warning will flash for a few seconds and the unit will turn itself
off. Replace the battery by sliding off the battery cover at the back
of the unit, unclip the exhausted battery and replace with a new
battery of the correct type.
Note: if the battery is not to be used for long periods, the battery
should be removed to prevent damage to the instrument by possible
leakage.
Calibration Check
The MicroDL is calibrated to read in litres at body temperature,
barometric pressure, and saturated with water vapour (BTPS) for
FEV1 and FVC. The units of PEF are litres per second BTPS or litres