Campbell CR300 Series Product Manual page 21

WARNING:
Sustained input voltages in excess of 32 VDC on CHG or BAT terminals can damage the
transient voltage suppression.
Ensure that power supply components match the specifications of the device to which they are
connected. When connecting power, switch off the power supply, insert the connector, then turn
the power supply on. See
Following is a list of CR300 series power input terminals and the respective power types
supported.
BAT terminals: Voltage input is 10 to 18 VDC. This connection uses the least current since
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the internal data logger charging circuit is bypassed. If the voltage on the BAT terminals
exceeds 19 VDC, power is shut off to certain parts of the data logger to prevent damaging
connected sensors or peripherals.
CHG terminals: Voltage input range is 16 to 32 VDC. Connect a primary power source, such
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as a solar panel or VAC-to-VDC transformer, to CHG. The voltage applied to CHG terminals
must be at least 0.3 V higher than that needed to charge a connected battery. When within
the 16 to 32 VDC range, it will be regulated to the optimal charge voltage for a lead acid
battery at the current data logger temperature, with a maximum voltage of approximately
15 VDC. A battery need not be connected to the BAT terminals to supply power to the data
logger through the CHG terminals. The onboard charging regulator is designed for
efficiently charging lead-acid batteries. It will not charge lithium or alkaline batteries.
USB port: 5 VDC via USB connection. If power is also provided with BAT or CHG, power will
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be supplied by whichever has the highest voltage. If USB is the only power source, then the
SW12 terminal will not be operational. When powered by USB (no other power supplies
connected) Status field Battery = 0. Functions that will be active with a 5 VDC source
include sending programs, adjusting data logger settings, and making some
measurements. The maximum excitation on VX1 and VX2 is reduced to 2500 mV.
NOTE:
The Status field Battery value and the destination variable from the
(often called batt_volt or BattV) in the Public table reference the external battery
voltage. For information about the internal battery, see
Troubleshooting power supplies (p. 127) for more information.
Battery()
Internal battery (p. 109).
2. Wiring panel and terminal functions
instruction
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