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04-17-2017, 07:00 AM
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#1
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2 Rivet Member
2016 30' Classic
Washington, DC
, Washington, D.C.
Join Date: Dec 2015
Posts: 39
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APRS to monitor your Airstream?
We currently full-time in our 30' Classic but, every few weeks, we put the Airstream into storage while we check on our apartment back in DC.
I'd love to be able to use APRS to monitor things like battery voltage, interior temperature, etc. Has anyone else done this?
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05-21-2017, 12:14 PM
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#2
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Rivet Master
2015 30' Classic
Pleasanton
, California
Join Date: Jan 2015
Posts: 745
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Paul,
I think having the ability to monitor battery voltage and internal temperature is a great idea. I've already been caught out with my batteries dead after leaving the "Use" switch on while in storage only to find them dead when picking up the trailer for a weekend trip!
I've been thinking about the best way to implement this and here are the options I've come up with so far:
1. APRS using ArgentData's Radio Shield 2. This solution requires an Arduino and SRB MX145 Transmitter. The Radio Shield 2 looks pretty easy to program and sending EMAIL messages to an APRS Igate looks relatively straightforward. Total cost is $36 (shield) + $69.50 (VHF) radio + Arduino and packaging.
2. APRS using Tracksoar. This is probably the smallest solution. Again, modifying the software looks pretty easy and the board provides some expandability - SPI and I2C interfaces. Not sure if there is an unused analog pin to measure battery voltage, but I'm guessing there is, just need to check with Tracksoar. Total cost is $195 (Tracksoar) + $35 (Programming kit) + packaging.
3. GMS solution using Particle's Electron. The SIM card provided by Particle only permits internet data, so another gateway such as IFTTT would be required to send messages. The cheapest subscription costs about $3/month. Third-party SIM cards with SMS capability can be used for pay-as-go, but I haven't researched if there are cheaper monthly solutions. Total cost is $69 (Electron) + packaging.
Although the APRS solution would be very cool, and maybe even the lowest-cost solution in the long-run by avoiding recurring fees, it's not terribly reliable. Sending one or more APRS messages can easily be done, but I haven't figured ou a way to confirm that an EMAIL Igate message was sent.
So I'm thinking the requirements can better be met with the GMS solution. Thoughts?
__________________
Al, K6IV
2015 30' Classic, "Chez Nu"
2014 RAM 2500 w/Cummins Diesel
ProPride Hitch, 400 W Solar
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05-21-2017, 07:23 PM
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#3
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Rivet Master
2015 30' Classic
Pleasanton
, California
Join Date: Jan 2015
Posts: 745
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An even cheaper GSM solution could be the Dash by Hologram. It's an Arduino-based device with a GSM modem. The monthly cost is only $0.4 minimum and each megabyte is billed at $0.60. Since messages will likely be sent only when they exceed pre-defined limits, I would expect 1 megabyte to go a long way.
A GMS solution could easily respond to a received text message to report the battery or temperature status.
__________________
Al, K6IV
2015 30' Classic, "Chez Nu"
2014 RAM 2500 w/Cummins Diesel
ProPride Hitch, 400 W Solar
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02-20-2018, 09:52 PM
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#4
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2 Rivet Member
1964 26' Overlander
Palmyra
, Virginia
Join Date: Aug 2017
Posts: 68
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I would include at least one weekly report so you can monitor conditions and get an acknowledgement the system is active and working.
Further as long as you have the system in place I would include GPS positioning and movement alerts so you can notify police and track the trailer for recovery should it be stolen.
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02-20-2018, 10:19 PM
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#5
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Rivet Master
2015 30' Classic
Pleasanton
, California
Join Date: Jan 2015
Posts: 745
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APRS to monitor your Airstream?
Good idea. I’m currently evaluating a prototype of the system, so I’ll add a weekly status update. Messages only cost about 500 bytes, so I could send one every hour and still not exceed $1 per month.
I’ll post a few screenshots of my interactions with the system shortly.
__________________
Al, K6IV
2015 30' Classic, "Chez Nu"
2014 RAM 2500 w/Cummins Diesel
ProPride Hitch, 400 W Solar
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02-20-2018, 10:26 PM
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#6
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Rivet Master
2007 22' International CCD
Corona
, California
Join Date: Jul 2013
Posts: 9,180
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Look at the APRS solutions from Byonics.com. That’s what I’m implementing on my AS.
__________________
Rich, KE4GNK/AE, Overkill Engineering Dept.
'The Silver HamShack' ('07 International 22FB CCD 75th Anniversary)
Multiple Yaesu Ham Radios inside and many antennae sprouting from roof, ProPride hitch, Prodigy P2 controller.
2012 shortbed CrewMax 4x4 Toyota Tacoma TV with more antennae on it.
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02-20-2018, 10:48 PM
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#7
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Rivet Master
2015 30' Classic
Pleasanton
, California
Join Date: Jan 2015
Posts: 745
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I did take a look at the TinyTrak but didn't include it in my previous post because it doesn't include a transceiver.
Keep us posted on your progress!
__________________
Al, K6IV
2015 30' Classic, "Chez Nu"
2014 RAM 2500 w/Cummins Diesel
ProPride Hitch, 400 W Solar
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02-20-2018, 11:31 PM
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#8
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Rivet Master
2007 22' International CCD
Corona
, California
Join Date: Jul 2013
Posts: 9,180
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APRS to monitor your Airstream?
His MicroTrak version includes a Transmitter and GPS in the same package.
Look around a bit more. I have a very much older TT4 plus a small linear to boost its output. Trying to package it neatly, and the display is being a stumbling block to get it mounted neatly. DW will not let me just stick it somewhere with duct tape, unfortunately [emoji3]
__________________
Rich, KE4GNK/AE, Overkill Engineering Dept.
'The Silver HamShack' ('07 International 22FB CCD 75th Anniversary)
Multiple Yaesu Ham Radios inside and many antennae sprouting from roof, ProPride hitch, Prodigy P2 controller.
2012 shortbed CrewMax 4x4 Toyota Tacoma TV with more antennae on it.
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02-21-2018, 05:20 PM
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#9
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2 Rivet Member
1964 26' Overlander
Palmyra
, Virginia
Join Date: Aug 2017
Posts: 68
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I would also install a super cap between the supply and the device so as to self power for a bit if power runs out or is disconnected (think theft). Not sure how long or how many messages could be sent before the charge on the super cap dies but it's a thought.
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02-21-2018, 10:55 PM
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#10
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Rivet Master
2007 22' International CCD
Corona
, California
Join Date: Jul 2013
Posts: 9,180
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Small gel cell battery and charger circuit tucked into the very front end of my upper streetside overhead cabinet behind the end blank-off partition. The rest of the electronics lives in that area, out of sight. Takes a screwdriver to get in there.
__________________
Rich, KE4GNK/AE, Overkill Engineering Dept.
'The Silver HamShack' ('07 International 22FB CCD 75th Anniversary)
Multiple Yaesu Ham Radios inside and many antennae sprouting from roof, ProPride hitch, Prodigy P2 controller.
2012 shortbed CrewMax 4x4 Toyota Tacoma TV with more antennae on it.
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02-21-2018, 11:32 PM
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#11
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Rivet Master
2015 30' Classic
Pleasanton
, California
Join Date: Jan 2015
Posts: 745
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Quote:
Originally Posted by Scoutx
I would also install a super cap between the supply and the device so as to self power for a bit if power runs out or is disconnected (think theft). Not sure how long or how many messages could be sent before the charge on the super cap dies but it's a thought.
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Not a bad idea, but given that the average current is typically 50 to 200 mA for up to tens of seconds, trying to hold the supply with a super cap would be difficult. $12 gets you a 10mF capacitor. So trying to hold say 2 V for 2 A*s would require a capacitor = 2 A*s / 2 V = 1F. Probably a more cost effective solution would be to add a backup lithium cell. It's certainly worth a look.
__________________
Al, K6IV
2015 30' Classic, "Chez Nu"
2014 RAM 2500 w/Cummins Diesel
ProPride Hitch, 400 W Solar
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02-21-2018, 11:35 PM
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#12
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Rivet Master
2015 30' Classic
Pleasanton
, California
Join Date: Jan 2015
Posts: 745
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Quote:
Originally Posted by rmkrum
His MicroTrak version includes a Transmitter and GPS in the same package.
Look around a bit more. I have a very much older TT4 plus a small linear to boost its output. Trying to package it neatly, and the display is being a stumbling block to get it mounted neatly. DW will not let me just stick it somewhere with duct tape, unfortunately [emoji3]
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I didn't see the MicroTrak, but it's certainly in the right direction. I'll be curious to see how well the system performs.
__________________
Al, K6IV
2015 30' Classic, "Chez Nu"
2014 RAM 2500 w/Cummins Diesel
ProPride Hitch, 400 W Solar
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02-21-2018, 11:53 PM
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#13
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Rivet Master
2015 30' Classic
Pleasanton
, California
Join Date: Jan 2015
Posts: 745
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Here's an example of what I have so far...
The first image shows the monitor responding to a help command and what happens when you send text that it doesn't understand.
The next image returns the current status and history.
The next image shows the settings and what's reported when a setting is changed successfully. Although I didn't include it, the monitor will respond with instructions for the correct format if it was unable to parse the message correctly.
The next image shows the cell tower triangulation feature.
Clicking on the map opens up google maps as shown below.
Not shown are the alerts which will arrive by SMS if any of the preset limits are exceeded. My next goal is to add a door switch, alarm output and shore power detection. These additions are pretty easy, I just need to find the time. Since the monitor is SMS based, there's no dedicated smart app and it should work with any cell phone.
__________________
Al, K6IV
2015 30' Classic, "Chez Nu"
2014 RAM 2500 w/Cummins Diesel
ProPride Hitch, 400 W Solar
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02-22-2018, 03:59 AM
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#14
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4 Rivet Member
2018 27' Flying Cloud
Austin
, Texas
Join Date: Mar 2016
Posts: 375
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So what did you end up with that is sending you the text messages with the status updates? Looks like a fairly clean report.
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02-22-2018, 09:19 AM
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#15
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Rivet Master
2015 30' Classic
Pleasanton
, California
Join Date: Jan 2015
Posts: 745
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The monitor is based on the Dash module, by Hologram.io. It's an Arduino microcontroller with a built-in cell modem. These modules cost about $69 and the monthly cost is only $1.
On my todo list are the following things:
1. Automatically send a weekly status update.
2. Add shore power detection.
3. Look at adding a lithium backup battery and send an alert if the RV battery connection is lost.
4. Add a door input switch and alarm output and the software to remotely enable the alarm. If the system is armed and the switch opens, the system should send a text message and assert the alarm output (5 minute timeout).
5. Add optional feature to monitor two independent batteries.
6. Add optional feature to add two general purpose inputs and outputs.
__________________
Al, K6IV
2015 30' Classic, "Chez Nu"
2014 RAM 2500 w/Cummins Diesel
ProPride Hitch, 400 W Solar
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02-22-2018, 09:57 AM
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#16
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Rivet Master
2002 30' Classic S/O
Fleming Island
, Florida
Join Date: Nov 2013
Posts: 4,667
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Quote:
Originally Posted by alano
The monitor is based on the Dash module, by Hologram.io. It's an Arduino microcontroller with a built-in cell modem. These modules cost about $69 and the monthly cost is only $1.
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This is intriguing. What development tools are you using? Are they provided?
My Airstream is largely stored indoors in a secured facility, but there are times when it is stored in the open. This looks like a solution I could implement for those times.
Al
__________________
“You cannot reason someone out of a position they have not been reasoned into"
Al, K5TAN and Missy, N4RGO WBCCI 1322
2002 Classic 30 Slideout -S/OS #004
2013 Dodge 2500 Laramie 4x4 Megacab Cummins
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02-22-2018, 10:37 AM
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#17
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Rivet Master
2015 30' Classic
Pleasanton
, California
Join Date: Jan 2015
Posts: 745
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Quote:
Originally Posted by Al and Missy
This is intriguing. What development tools are you using? Are they provided?
My Airstream is largely stored indoors in a secured facility, but there are times when it is stored in the open. This looks like a solution I could implement for those times.
Al
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The Arduino IDE is free from arduino.cc or you can download it for free from Microsoft's Store. Hologram describes how to configure the Arduino IDE for use with the Dash. They have a reasonably good forum where you can ask questions. You can always ask me as well
__________________
Al, K6IV
2015 30' Classic, "Chez Nu"
2014 RAM 2500 w/Cummins Diesel
ProPride Hitch, 400 W Solar
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02-22-2018, 06:10 PM
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#18
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2 Rivet Member
1964 26' Overlander
Palmyra
, Virginia
Join Date: Aug 2017
Posts: 68
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Quote:
Originally Posted by alano
Not a bad idea, but given that the average current is typically 50 to 200 mA for up to tens of seconds, trying to hold the supply with a super cap would be difficult. $12 gets you a 10mF capacitor. So trying to hold say 2 V for 2 A*s would require a capacitor = 2 A*s / 2 V = 1F. Probably a more cost effective solution would be to add a backup lithium cell. It's certainly worth a look.
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Mouser Electronics
5.6V 90F 450Ws (401Ws @5V) minimum storage @$20
So let's assume 200mA for 30s per transmission
200mA * 5V * 30s = 30Ws.
Assuming a message every 10 minutes, you could track for at least 2 hours.
https://www.mouser.com/ProductDetail...1novKDOGKTY%3d
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02-23-2018, 09:57 AM
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#19
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Rivet Master
2015 30' Classic
Pleasanton
, California
Join Date: Jan 2015
Posts: 745
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Quote:
Originally Posted by Scoutx
Mouser Electronics
5.6V 90F 450Ws (401Ws @5V) minimum storage @$20
So let's assume 200mA for 30s per transmission
200mA * 5V * 30s = 30Ws.
Assuming a message every 10 minutes, you could track for at least 2 hours.
https://www.mouser.com/ProductDetail...1novKDOGKTY%3d
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Scoutx, I'll take a better look and compare a supercap and lithium cell. One thing I noticed is that the supercar has a fairly high leakage spec, 500 uA. I like the operating temperature range though.
__________________
Al, K6IV
2015 30' Classic, "Chez Nu"
2014 RAM 2500 w/Cummins Diesel
ProPride Hitch, 400 W Solar
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02-23-2018, 04:15 PM
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#20
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2 Rivet Member
1964 26' Overlander
Palmyra
, Virginia
Join Date: Aug 2017
Posts: 68
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Quote:
Originally Posted by alano
Scoutx, I'll take a better look and compare a supercap and lithium cell. One thing I noticed is that the supercar has a fairly high leakage spec, 500 uA. I like the operating temperature range though.
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Point, but let's put it another way, ignoring conversion loses, it would take about 200 days for that leakage to use 1Ahr from your battery. I suspect that the leakage current of floating a lithium battery would be far higher, given a self discharge rate of about 2-5% of the batteries' capacity per month.
Further lithium batteries do not like extremes in temperature and you always run a risk of something bad happening to the battery and thus potentially your trailer.
You did say it would be just a few weeks right?
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