Campbell Scientific CVS4200 / BVS4300 Stationary Samplers - Manual (Page 39)

CVS4200 / BVS4300 Stationary Samplers
FIGURE 7-1. Battery performance curve
7.5.2 Sampler Controller Backup Battery
The controller contains a 3.6 V 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 5 V to approximately
3.3 V. The rate at which this voltage drops is slowed by the presence of a
supercapacitor. By the time the voltage has reached 3.3 V, 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:
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