Alternative to automotive relay


I have built a boat monitoring gadget using the photon. One of the things I am monitoring is the duration of a bilge pump run time. This allows me to build alerts to notify me if the bilge is running for an extended period of time which would mean too much water is gong into the boat, i.e potential for boat sinking.

I am using automotive relays connected to the bilge pump so that when the bilge comes on I get 12v on the relay which triggers it. That allows me to read contact between 30 and 87 on the relay which tells me the bilge is on.

It works well but I really don’t like the wiring mess with the relays. I was looking into some rasp/arduino relay boards and even the particle relay board but wasn’t able to to determine if I can do the same with them. They seem more designed to trigger a high voltage as opposed to detecting high voltage.

Any suggestion on how to make a cleaner setup without automotive relays?



You could use a (non-invasive) current sensor to monitor the pump. Or use a float sensor to detect the water level.

I recently used some of these MOSFET’s to allow the Photon to switch 12v High current power. You could use it to also flip your realy on/off or to supply power directly to your pump if the current to run it is not too high.

@andrepio, you could use a DC current sensor like this one:

It needs to be inline with your pump power, assuming it is DC and does not use more than 5A. Another version of that is this device:

You could also replace the relay with it and remove the shunt resistor to just measure the voltage across the pump or use it like the first device, assuming the current doesn’t exceed 3.2A.

The first device has a analog output while the second uses I2C. Detecting current and/or voltage should do what your looking for.

I started a similar bilge pump monitor, though I experimented with a Hall Effect sensor like this …