Humidity/Temperature Alarms

Hi all-

I’m working on a small circuit to help prevent e-foil disasters. It’s super simple! It is an alarm which goes off if humidity or temperature exceed preset values. It will hopefully notify the rider of water ingress into a sealed case or of an overheating issue. I am thinking of doing a beep which starts at some rate and gets faster as the values go higher.

At what humidity value would you sound the alarm?

At what temperature value would you sound the alarm? In the ESC box? In the battery box?

I look forward to hearing you input on these numbers.


Note: Another option is to have the circuit sample current humidity/temperature after it starts up and could alarm on any increases in either value. Additional thought made me realize hard coding humidity thresholds reduces versatility. What if you live in a humid place? Still need some help figuring out how much of an increase is significant.

I have such system already, low budget version. The water sensor did a great job so far and get me off the water a couple of times. For temperature I have no warning but can simply check box inner temperature.

There is a video in my build about the water sensor (Newcomer build)

Excellent! I’m always glad when I’m beaten to the punch with a safety system. It sounds like humidity sensor might not work? I had the concern in mind as well, water ingress as a liquid might not mean a change in humidity. I’ll look at your build thread now. Thanks for the input.

Well I think liquid water is more of an issue than vapour one. I placed two sensors in my box, both on the very bottom. So in case there is water floating around you will have a high chance to hit the sensor. My electronics are placed above ground level, in case there is water inside it will not hit electronics directly. The sensor is super sensitive which is not only good as it might sound. I got condensed water by time around the cooling pipes which could activate the sensor. Once it is on you need to open and dry it otherwise you foil like police :slight_smile:

That’s hilarious! I’m using the Maytech V2 remote and fortunately there is a relay on there I can use for this. Switch it off with the button on remote and head into the beach ones it goes. Can you link to the water sensor you use? I couldn’t find it in your build thread only the video of the siren you use. Super funny.

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You actually don’t want to cut it off if the alarm goes. The highest chance you have of leakage is when you are lying on the board. If you cut off in the middle of a body of water you will then take on a lot more while getting ashore.
It makes more sense to sound an alarm, then head to the beach/jetty, and once there cut off the power and dry out. That way you minimise the amount of water intake.

Totally agree, this is also how I handle an alarm.
Other scenario would be a lose cooling pipe. Therefore I have an external switch to cut off pump only

Sorry I think you misunderstood. The relay would only turn off the alarm leaving the board operational to return to shore.

Are you using Maytech V2 remote? There are two accessories. One for pump one for alarm.

I am using the cheap remote from eBay. Pump and sensor is run independently. If you scroll above you will find a blue button in my pic. This is for the pump. The other one, yellow, is for esc

It’s a very nice design. I hope you stick around to see my implementation. I’m using this case from Polycase for battery compartment.


The case will have my phone running Vesc Tool displaying information and battery information using two of these. An alarm will sound on these for battery voltage.

The circuit this topic is about will live in the ESC case is the rear and this case. The ESC version is able to be turned off by the remote. The version in the case I need a way to turn off. I am only using two cable glands in battery box to minimize ingress possibility.