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Thursday August 21, 2008
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Power Use Calculations for MP406 Soil Moisture Sensor & Interfaces1. Power Use CalculationsThe following sets out the power supply calculations for a single SMD4-P interface with 4 x MP406 connected and then calculates the power consumption for a typical soil moisture station with 6 x SMD4-P and 24 x MP406 measuring soil moisture once per 20 minutes. 1 x SMD4-P interface uses 0.12 mA continuously for maintenance of the DataBus connection. In this "idle" state the interface is fully responsive and its clock continues to keep time. Power usage will accelerate up to 2.4 mA if a response is required but immediately drops back once the message is sent. The actual power consumption at 12 volts is 0.12 mA continuous and 25 mA for 5 seconds during measurement of the single channel. Then 1 x SMD4-P uses/day 0.12 mA x 24 hours = 2.88 mA hours 1 x MP406 sensor uses 25 mA when turned on and measuring soil moisture. Note: All 4 x MP406 connected to the SMD4-P interface are powered for the full time needed to take a reading by all 4 x MP406 in each 20 minute reading cycle. This is 5 seconds / MP406 or 20 seconds each / 20 minutes for each sensor.
Then power use to all 4 x MP406 connected to the SMD4-P interface per day is:
Then the power use of the SMD4-P interface with 4 x MP406 sensors with 20 minute readings per day is:
Then power use of 6 x SMD4-P interfaces each with a 4 x MP406 connected with 20 minute readings is per day 2. Power Supply Options
A 20 watt solar panel used in conjunction with a 20 ampere hour Gel Cell battery will provide sufficient power supply for continuous functioning of a system with 6 x SMDP-A interfaces and 24 x MP406 sensors. © 2003-2008, ICT International | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||