I just got a text from my boat.
In November, I wrote about how to protect your boat from frozen engines and dead batteries with smart sensors. These Internet-connected devices can “call” you when problems arise.
Well here is the update. I built a monitor for about one-fifth the cost of commercial models. My device is bare bones, but it has the critical features I wanted.
Over Thanksgiving, I sat down with a cup of coffee and ordered a starter kit from from Adafruit.com. Adafruit sells Arduino and other hobbyist electronics. The starter kit arrived a few days later packed with an assortment of parts. Boards, wires, processors, battery packs, buttons and knobs came in the box. I was eager to get started on the project.
I’m no programmer, so I had to learn enough ‘C’ computer language to run the sensor instructions on the Arduino “brain.” After lots of reading at Arduino.cc (and the Adafruit website) I had simple functions working. First, I saw temperature readouts from the sensor to my laptop — a good first step.
Over the following weeks I devised new, more useful configurations. My friend and fellow boater Dave helped me think through the logic for sensing and alerting.
Before texting would work, I had to head over to T-Mobile and pick up a SIM card like the one in your cell phone. SIM cards — about the size of a thumbnail — identify your unique device and phone number on the cell network. For $3 per month I get 30 texts or 30 minutes of calls (with no contract). I won’t be using voice calls. That’s a pretty good deal.
After more wiring, soldering and coding I got my first text from the gadget! Using code lines like
dtostrf(vbat,3,0,battText); //convert battery floating # into char
the sensor can alert me on temperature and power thresholds I set.
It was easy to test temperature increases because I could start at say 70 degrees and hold my finger on the temperature probe. Heat from my fingertip would cause the temperature to rise past the threshold I set, triggering a text to my cell phone.
Finally, I programmed the Arduino to answer back whenever I ask “what’s up?” If I text the word “status,” the sensor sends back battery voltage and temperature. Below you’ll notice it was around 60 degrees and the battery was still charging up. Cool! [Note: the battery voltage you see is for the cell radio battery in millivolts. I use that voltage as a proxy for shore power. Logically, I know that if the shore power is running the battery is charging and voltage will be above 4000 millivolts. If it drops below 4000, I can infer that shore power was lost because the unit switched to battery and it’s slowly discharging below 4000.]
I tested in the garage for several days over a range of temperatures and it worked well. I’ll install the sensor — in its Container Store plastic box — this weekend in the boat.
I’m satisfied with the result and pleased I was able to get it working. Now that I’ve discovered this technology I’m looking for my next project (maybe a wind station on my boat).
You may not be a programmer, but I am so glad that you are a “Tinker”! Love this post. Hope your boat starts calling even more….
Steve – That is a pretty clever idea, and I can see other boaters grabbing on to it. By the way, do you have any type of solar collector for topping off the batteries. I finally sent off a few boating books today you might find interesting -espec. the one about “Iceblink”. We met the couple in Nova Scotia the last time we were there. Nice people. Bob Sent from my iPad
Thanks so much for shipping those books! I can’t wait to see them. Very kind of you.
I don’t have solar yet for the batteries, but I’ve always thought it might be a good upgrade for me.
Well, Steve … That is terrific … Would you knock one out for me now? (Heh, heh) … Do you know anyone who makes a device like this ready to use “out of the box”? I don’t think I’d ever be able to do what you did!
Hey, Russ. You could be my first customer when I go commercial!
Check out Boat Command. They have a unit that starts around $300 and $9 per month. My friend Dave installed it on his 24′ powerboat and gave me access to see it online. It’s pretty cool!
Hello… Wonderful project, congratulations on your tenacity (I know…), and a great design.
I made this same thing some while ago with Arduino (Sparkfun and Adafruit sensors and boards). I love showing people my phone and saying “my boat just tested me.”
After, I found Siren Marine’s Sprite and replaced my stuff with that in order to have a properly packaged device and it has been working great for years.
My arduino went on to other projects. Don’t know why more boaters are fiddlin’ with this sort of electronics, so fun. So, what’s the plan for your wind project? I need a new project… I was mast camera or some such, and MMS instead of SMS output or “intrusion-triggered camera MMS”. MrsO of blog sailpinga.wordpress.com
Hi, SailPinga. Thanks for the note. I always enjoy talking about and hearing from fellow sailors. And how cool that we both made similar projects!
In fact, my friend did the same as you. After some Arduino tinkering he went with a commercial product at Boatcommand.com.
Intrusion detection sounds cool too. I have not done much on the wind project lately – need to get back on that!