Campbell Scientific PVS4100/4120/4150 Portable Automatic Samplers - Manual (Page 35)

Section 3. Operation
3-5
3.3.2 Battery: Microprocessor
SAMPLER CONTROLLER BACKUP BATTERY
The controller contains a 1/2AA, 3.6V lithium backup battery to maintain user
settings during loss of system power. If power is removed for any reason, the
controller will start a planned shutdown procedure which will save all user
settings while its operating voltage is reduced from 5V to approximately 3.3V.
The rate at which this voltage drops is slowed by the presence of a
supercapacitor. By the time the voltage has reached 3.3V, the controller has
safely stored all user settings and entered a “sleep” mode. This is an extremely
low-power mode which is maintained by a trickle of current from the lithium
battery, and can be maintained for many years under normal circumstances.
The battery is located on the top left hand side of the controller. It is accessible
by the removal of the clear cover, and should be changed under powered
conditions. Since the controller is a low-power device, this uncovering can be
safely done, taking care that no conductive implement contacts sensitive circuit
components.
If the controller starts to exhibit certain operating anomalies such as loss of
user settings after sustained power outages or an inability to “wake up” after a
normal shutdown, it may be due to a low or totally discharged backup battery.
To predict the probability of these events, regular examination of the battery
condition is encouraged. The battery status is easily determined while the
controller is active. The process will not affect a running program. Battery
status can be checked by use of the following touchpad sequence:
VIEW, OTHER OPTIONS,
select MAINTENANCE, ENTER, then select B/U BATTERY TEST, ENTER
The display will then show “PASSED”, “LOW” or “FAULT”. The latter two
require battery replacement.
TO REPLACE BATTERY
1. Make sure the controller is powered.
2. Remove touchpad (clear) cover from the controller, remembering to
handle internal ribbon cable and connector with care.
3. Locate the battery holder on the normal left side of the circuit board. The
battery is a 1/2” cylinder about 1” in length. The positive (+) end of the
battery has a raised button. Note the button’s relative position in the
holder. It should be pointing away from the display side of the board.
4. Place new battery in holder, noting position of button with respect to the
polarity indicators in the holder.
5. Check battery status, as above. If necessary, locate small white button at
top of the control board (under display) and push to restore factory
defaults.
6. Replace cover securely and re-enter user settings.