Campbell Scientific CR23X Micrologger - Manual (Page 230)

SECTION 14. INSTALLATION AND MAINTENANCE
14-4
14.3 CR23X POWER SUPPLIES
The CR23X is available with either alkaline or
lead acid battery options. It may also be
purchased without a battery option.
10 D-TYPE ALKALINE BATTERIES
FIGURE 14.3-1. Alkaline Battery Orientation
While the CR23X has a wide operating
temperature range (-40 TO +80°C), the battery
bases have more limited operating ranges.
Exceeding these ranges will degrade battery
capacity and lifetime and could also cause
permanent damage.
14.3.1 CR23X ALKALINE BATTERY BASE
Install alkaline batteries as shown in Figure
14.3-1.
Temperature range: -25° to +50°C (Table
14.3-2).
The CR23X utilizes 10 alkaline D cells. After
battery installation, the power switch on the side
of the CR23X will turn the datalogger on and off.
A fresh set of ten high-quality alkaline D cells
can be expected to have about 10 amp hours at
20°C.
Voltage with ten new D cells is about 15.5 V. If
external power is connected to the CR23X with
the alkaline power supply, power will be drawn
from the source of highest voltage. In a typical
configuration using an external lead-acid
battery, the D cell voltage will discharge from
15 V to about 12 V before the lead-acid battery
starts to supply current. This means the D cells
will lose approximately 35% (15 Ah - 9.8 Ahr =
5.2 Ah) of their capacity before the external
power takes over.
The amp-hour rating decreases with
temperature as shown in Table 14.3-2.
Datalogger Instruction 10 can be used to
monitor battery voltage. Replace the alkaline
cells before the CR23X battery voltage drops
below 11.0 V.
A thermal fuse in the alkaline base will allow a
current drain of 1.85 A at 20°C (1.3 A at 50°C).
In event of a short, the thermal fuse will cut
power after about 40 seconds.
TABLE 14.3-2. Typical Alkaline Battery
Service and Temperature
Temperature ( o C) % of 20 o C Service
20 - 50 100
15 98
10 94
5 90
0 86
-10 70
-20 50
-30 30
NOTE: This data is based on one "D" cell
under conditions of 50 mA current drain
with a 30 ohm load. As the current drain
decreases, the percent service improves for
a given temperature.
14.3.2 CR23X LEAD ACID BATTERY BASE
Temperature range: -40° to +60°C
(Table 14.3-3).
Charging voltage: 17 to 24 VDC or
18 V RMS AC.
The CR23X includes a 12V, 7.0 amp-hour lead
acid battery, an AC transformer (18 V RMS AC),
and a temperature compensated charging
circuit with a charge indicating LED (Light
Emitting Diode). An AC transformer or solar
panel should be connected to the base at all
times. The charging source powers the CR23X
while float charging the lead acid batteries. The
internal lead acid battery powers the datalogger
if the charging source is interrupted. The lead