VEGA PLICSMOBILE GSM_GPRS radio module - Manual (Page 9)

4 Battery operation and power saving mode
4 .1 Battery operation
If no network-supported voltage supply is available,
PLICSMOBILE can be also powered via the battery. You can find
detailed specification for voltage supply in chapter "Technical data".
The power saving mode should be switched on in battery operation
and time-controlled measured value transmission and the sensor
should be set to HART multidrop mode to increase the running time
(details se chapter "Power saving options").
4 .2 Battery sizing
When selecting an external battery/accumulator, the
following points must be observed:
Power consumption in power saving mode:
If a battery or an accumulator is used which cannot be charged
cyclically, then the power saving mode should be activated. With an
operating voltage of e.g. 12 V, a standby power consumption of
0.3 mW must be taken into account. With an assumed lifetime of e.g.
one year, the requirement is approximately 2.6 Wh, which corresponds
to a battery capacity of 0.22 Ah at 12 V. The standby power
consumption with specific operating voltages is stated in the
"Technical data".
Power requirement complete measurement cycle incl. measured
value transmission:
A measurement cycle lasts approximately 60 to 120 seconds
(dependent on sensor type and network quality) and includes
automatic switching on of the sensor (HART multidrop mode with
4 mA), recording of the measured value, measured value transmission
and a return to the power saving mode. During this time, a power of
approximately 20 mWh is required. For example, with one measure-
ment per day, this adds up to approx. 9.6 Wh per year, which
corresponds to a battery capacity of approx. 0.8 Ah at 12 V.
Examples for battery capacitance dependent on the number of
transmission cycles
Number of mes-
sages/day Annual consumption PLICSMOBILE
Standby energy
demand Energy demand
for message
transmission Required bat-
tery capacitance
with 12 V
1 2.6 Wh 9.6 Wh 0.8 Ah
2 2.6 Wh 16.8 Wh 1.4 Ah
PLICSMOBILE • GSM/GPRS radio module 9
4 Battery operation and power saving mode
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