Thursday, April22, 2021
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DIY Boat Monitoring System

Every morning when I get up there is an email ready for me from my boat. I can look at that and see that the main pump did not go on (good), that the small pump ran for it's usual 5 seconds (also good), that the battery is charged, the shore power is on, and the 12 volt vent fan is on. (all good) These all come to me from the marina WiFi and a module based on the amazing ESP-32. In these few pages I am going to tell you not only how I built it, but I am going to give you information you need to build one yourself. If you do decide to build one, there are some skills you will either need to have, or learn. HERE are some of them. There is a second version of this project that is being built by a friend in The Netherlands that uses a G2 Cellular network. It is based on the same information I am sharing here and should be completed in the next few months.

This module draws very little power off the battery. It would probably run for a year before draining the battery and by then a typical battery would be dead anyway from self discharge. The unit wakes up every half hour for a fraction of a second if nothing is going on and for a few seconds if it has to send an email. I have it set to send an email at 6AM every morning just so I know the unit itself is working.

There are a couple of things that are unique to my boat and I am sure every boat owner will want something different. That is why I structured the software in a modular fashion so each task has a tab and the main program calls these tasks one after another. Each task can add to the final report and indicate if its report needs to go out right away, or only on the daily status call.

To the right is a copy of one of the emails my boat sent me. It tells me everything is OK. A bit of background. My boat is old and wood and leaks. The main thing I want to know is the conditions of the pumps. I have a large pump that only goes off if the small pump fails or the boat is trying to sink. If the float switch lifts, the monitor wakes up and sends an email alerting me. Otherwise, I run the small pump and monitor how long it stays on. It is an auto pump that normally goes on every 2 1/2 minutes and fails every 4 years. With the monitor, it goes on once a day once it builds up a history of not pumping significant water. Hopefully this will extend its life beyond 4 years. The monitor knows if I take the boat out when I turn on the main boat power and switches the small pump to auto and otherwise stops monitoring. But when the main power is back on, the pump will initially run every half hour and then every hour and then after about a day it will only be running once a day. If sailing opened up the seams and the boat takes more time to seal itself up, the monitor will know and keep running the pump more often to keep up. The other thing that is unique is that I have a very powerful 12 volt fan in the bow to keep the boat dry. But I don't want that fan running if either the battery gets low or shore power is off. Both these conditions are monitored and if detected the fan is turned off until the situation is corrected. To accomplish these tasks, there are two relays in the module. They are what is called latching relays which means a 20 mS pulse on one line will close the relay and a similar pulse on another line will open it. There is no power draw otherwise. There are two analog to digital converters (ADC) utilized on the ESP32 to measure the two 12 volt batteries.

In the pages that follow I will discuss the following. You can click on any of these to jump to that page or click on NEXT at the bottom to go to the next page.



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