Building and Operating a Solar Powered APRS Weather Station

Clay Jackson

N7QNM

Who is this guy?

• Data Geek

• Licensed in 1991

• APRS since 1991

– WetNet

– Xastir

• Interested in weather for 50 years

• Weather Station since 1995

– Davis WM II

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Why report the weather?

• Personal Impact

– Sailing

– Search and Rescue

– Data

• Public Service

– CWOP

– NOAA/SKYWARN

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APRS

Automatic Position Reporting System

• © Bob Bruninga

• GPS Position Reporting

• But much more

– Search and Rescue

– Messaging

– Weather

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APRS Network

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APRS Weather

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N7QNM Weather

• Combine APRS and Weather

• Get involved in CWOP

• Old Weather Station

• Linux Bigot

• 1995

• Xastir

• Meteo

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Challenges

• Property in Eastern Washington

• Farming

• No power

• No Internet

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Design Criteria

• Solar Power

• Reach a Digi

• Self Contained

• Inexpensive

• Not many choices

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Components

• Weather Station

• TNC

• Radio

• Antenna

• Solar Panel

• Charge Controller

• Battery

• Solar Panel Bracket

• Stevenson Screen

• Mast/Mount

• Box for Radio/Battery

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Weather Station

• Argent Data ADS-WS1

• Dallas Semiconductor 1-wire based

• TNC/WX All-in-One

– Wind Speed/Direction

– Temp/Humidity

– Barometer

– Rain Gauge

• Inexpensive

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Radio

• ICOM T7H

• Daughter’s old radio

• Low power drain

• Small form factor

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Antenna

• Vashon Radio Club J-Pole at 12’

– 1ST model

• Cushcraft Ringo at 22’

– Improved digi/igate coverage

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Solar Panel

• Harbor Freight

– 5W Panel

– Discontinued

• New/Better technology

– 50W in almost the same form factor

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Charge Controller

• 3A Controller from All Electronics

• �http://www.allelectronics.com/make-a-store/item/SCN-1/3A-SOLAR-PANEL-VOLTAGE-CONTROLLER/1.html

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Battery

• Radio Shack 7AH Sealed Lead Acid

• 1st one failed

– Exceeded power budget due to weather station transmit parameter

• Current battery in service for over 1 year

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Solar Panel Bracket

• 1st Attempt

– Home Depot aluminum angles

– Too flimsy

• Custom fabrication

– ¼” Aluminum tubes

– Tork-Lift Welding (Kent)

– $125

• Oriented due South – 18 degree tilt

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Stevenson Screen • Keeps direct sun and rain off the

Temp/Humidity sensor

• Ambient Weather

– SRS100LX

– www.ambientweather.com

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Mast/Mount

• 1” 10’ Radio Shack mast

• 5’ section in a 5 gallon bucket of concrete

• Guy wires in 1 gallon (10 lb) buckets

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Box for Radio/Battery

• Cutler-Hammer from Home Depot

• Plywood backing for terminal strip

• Sealed against weather

• Heat dissipation apparently not an issue

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Power Consumption

• Weather Station 100 mA (max)

• Radio

– Receive – 16 mA muted

– Transmit

• 700 mA (low)

• 1.6A (high)

• Duty Cycle – 2 minutes on every 20

• Initial Budget ~800mA = .08AH

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Power Input

• 12 V (nominal) panel

– Actually between 10 and 15 V

• 5 W Rating

• De-Rate 50%

• Worst case 200 mA = .2AH

• Duty Cycle

– 3 hours/day in mid-winter

– 12+ hours/day in summer

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Power Realities

• Being conservative was the right approach

• Weather station parameters

– Change in wind direction triggers transmit

– Initially set to 20 degrees

– Transmitting every 2 or 3 minutes during wind events

• Need high power to hit digipeater/igate

– Inversions common in winter

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Real Consumption

• Transmit Avg about 5 times/hour

• Power consumption close to 2A during transmit

• .2AH (instead of .08)

• Break even power consumption

• About 35 hours of battery life with no charge

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Construction

• 5 Gallon bucket with 2” pipe

• Sealed Cutler-Hammer box to contain radio and battery

• Weather Station in Stevenson Screen

• Mast and Antenna on Solar Panel Bracket

• Terminal Strips for wiring

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Testing

• Back yard at old home

• Sensors sheltered from wind

– Missed the wind direction issue entirely

• Used 5 Gal bucket w/2” pipe as temporary support

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Improvements

• Added a 10’ mast section

• Changed antenna

– Cushcraft 2M Ringo

• Change reed switch in rain gauge

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More Improvements

• Additional 1-wire Sensors

– Soil Temp

– Insolation (Solar)

• Cloud Cover

– Steel Ball and Camera

• Changes to Xastir

– Weather Server

– Record weather from other stations

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Weather Network

• KC7RAS-8

– Columbia Center in Seattle

– ADS-WS1

• Hard power

• Aspirated Box

• Mocom Exciter

• Anemometer failed at 60K

• N9VW

– Has my old Davis WMII

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CWOP

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CWOP Details

• 10,000 Registrations

• 6,000 active stations/day

• 40,000+ observations

• “Ground Truth” for NOAA/NWS

– Another Amateur Radio Public Service

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Sample QC Graph

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Q & A

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THANK YOU!

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Building and Operating a Solar Powered APRS Weather Station

Clay Jackson

N7QNM