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I'm using a typical Blue Seas automatic charging relay aboard. On the ACR, there is a ground circuit that can illuminate a LED to notify you when the relay is closed and the batteries are in parallel. The instructions show installation of the LED from the positive of the battery terminal to the post on the ACR. So my understanding is the ACR essentially "grounds" the circuit on the negative side and the LED illuminates.

My question is, how would you hook this up to digitize the circuit for SignalK on an RPi? Seems as if you would be sensing voltage all the time, with the hook up on the positive side of things? Could I replaced the LED with a voltage divider (I have a few of these) and use a ADS1115? Or would the ground on the Pi defeat the issue and ground the circuit? My initial logic is the open circuit reads "0" volts and closed "12," in which case, I could set a boolean variable of 0/1 to signify relay is open or closed and light an "LED" in WhilhelmSK. Not sure it's worth all the effort, but if it were easy, why not?

Steve
(2022-01-23, 01:00 AM)SCarns Wrote: [ -> ]I'm using a typical Blue Seas automatic charging relay aboard. On the ACR, there is a ground circuit that can illuminate a LED to notify you when the relay is closed and the batteries are in parallel. The instructions show installation of the LED from the positive of the battery terminal to the post on the ACR. So my understanding is the ACR essentially "grounds" the circuit on the negative side and the LED illuminates.

My question is, how would you hook this up to digitize the circuit for SignalK on an RPi? Seems as if you would be sensing voltage all the time, with the hook up on the positive side of things? Could I replaced the LED with a voltage divider (I have a few of these) and use a ADS1115? Or would the ground on the Pi defeat the issue and ground the circuit? My initial logic is the open circuit reads "0" volts and closed "12," in which case, I could set a boolean variable of 0/1 to signify relay is open or closed and light an "LED" in WhilhelmSK. Not sure it's worth all the effort, but if it were easy, why not?

Steve

Could you use an optocoupler to separate the 12V side from the 3.3V GPIO pin on the Pi. after that you would just need to work out if you need pull or pull down (likely same as the ST1 circuit) and then how to get this signal understood by Signal K and what the signal K message should be:

/vessels/<RegExp>/electrical/combiner

on/off or isolated/combined