Trek said..
I did the same thing about 5 years ago with a PIC microprocessor to warn me if the batteries were low or the bilge pumps were on when I bought a boat with very dodgy sea cocks. I gave up on the internet though because I found it unreliable and went with SMS.
Because all my friends wanted one it grew and grew and grew.
Now it can tell you where the boat is, monitor 2 batteries (since most yachts have x2), solar panel charging, gas, bilge pumps, shore power and a fridge (inspired by arriving at boat one day to find fridge failed bait had melted very pongy and warm beer). The solar panel monitor was added because a mate got his solar panel stolen!!
It even can turn on your deck lights or a siren remotely to scare away prowlers. This is whats its grown to now www.trektransponder.com.au. Anyone who wants to try the one on my boat in Pittwater, SMS the word "status" (without quotes) to 0431 935 720. :-)
And theres one that monitors a battery and charger only on 0435 142 275. If you SMS the letter "M" to that number (without quotes) you can check the battery charging on a test unit up north. (M is abbrev. for measure). Or "Trend" to see whats been happening.
Sweet! I can definitely relate to the fridge incident too
I can see adding a lot additional vital signs too, as the Arduino has plenty of spare pins, and adding additional alarms is just one line of code (ok, technically, it's just a struct initialization).
I went with the data (via Telstra 4G) though because I've found it to be more reliable than SMS in my area. My 4G connection uses a 5m-tall antenna, and I often get data where I can't call voice or SMS. In particular, Kangaroo Island has a crap mobile phone network.
Also, even if the Internet connection is temporarily lost, it's no big deal as the Arduino will keep contacting the server until it eventually gets through. It is the service that is responsible for sending the emails, and the emails are of course free
