Sutron Corporation X-Link Operations & Maintenance Manual, Rev 1.63 5/24/2016 pg. 188
22.2.
Power Budget Calculations
The power budget needs to be calculated for the proper selection of the station battery
and solar panel size. Simple stations with hourly sensor measurements and hourly
transmissions frequently get by with a 4 AHr battery and a 2 Watt solar panel.
Here are some key consumption figures at 12.5V:
X-Link Quiescent Current
= 0.50 mA
X-Link active
= 4.5 mA
GPRS Listening Enabled
= 9.6 mA (continuous operation average)
GPRS SMS transmission
= 15.5 mA (1 Tx average over 140 sec, 3/4 sig str.)
Transmitting GPRS
= 21 mA (1 Tx average over 140 sec, 3/4 sig str.)
Transmitting CDMA
= 27 mA (1 Tx average over 170 sec, 2/4 sig str.)
Transmitting Iridium
= 125 mA (1 Tx average over 15 sec, 5/5 sig str.)
Iridium Listening Enabled
= 29 mA (continuous operating average)
WiFi On
= 16.2 mA
Transmission averages are measured from exiting quiescent state to entering quiescent
state. A single GPRS transmission takes 140 seconds to complete the task and draws on
average, 21 mA over that time period.
Perform calculations to determine battery size and solar panel size following the guidance
found here:
http://www.sutron.com/customerservice/Conversions_Calcuations/PowerBudget.htm
Example: 2 sensors reading once per hour for 3 seconds at 25ma per sensor.
Transmission once per hour via GPRS. Listening disabled.
Task
Current
Percent Time
Average Current
Collecting
20 ma
3/3600
0.017 ma
Transmitting (3/4)
21 ma
140/3600
0.817 ma
Sensor
50 ma
3/3600
0.042 ma
Active
4.5 ma
5/3600
0.006 ma
Quiescent
0.80 ma
1
0.80
Total Avg Current
1.682 ma
Total Average
Power @12.5V
21.0 mW
Battery Life (4 AHr)
Full capacity
2,378 Hours/99 days
Rated Batt Life
75% capacity
1,783 Hr/74 days
Solar Size (10X)
210 mW (5 Watt
Panel is sufficient)
