question

Probably be much simpler to use a function node that way you can combine the timer and SOC arguments with &&. You can call and set the SOC to a flow message using a change node then use it in the function node. You can combine several conditions in one function node and output a single payload message to the relay control. Clear as mud?

Hi
appreciate feedback.
A function node seems to be pretty powerful. would also make the flow much simpler.
unfortunately I'm not familiar with javascript ...
Do you recommend any code examples to adopt ?

...although a function node can make it more simple, I don't think that this alone would suffice.

Node-red is event driven. There are two events / states that need to be combined when evaluating the logic.

Timer-event and SoC%-change event....both occur asynchronously in time to each other.

I suggest to store the last state of each event in a flow variable (context variable) when it happens. then evaluate the logic (AND) from both, every time one event occurs. Regarding context stores in NR, see https://nodered.org/docs/user-guide/context

Why don't you just use the first switch on the left? It checks, if SoC is below or above, and then you get two paths for the respective SoC. The asynchronous events are no problem in your case, as the AND is blocking (sending no message) until both events are registered by the AND.

I did not check everything, but it seems that you just need another change node for the second output of the switch and it works.

flows.txtHere's my untested flow. I use something similar on my system. My flow shows my devices, but you can easily adapt it for your devices.

The first flow saves the SoC in a global context called StateOfCharge everytime SoC changes.

The second flow triggers the flow with Off/On at 12pm/1pm respectively. The SetRelay functions that gets the SoC saved it the global contexts and executes the logic to set the relay state appropriately.

SetRelay function body:

var soc = global.get("StateOfCharge");
if (msg.payload == true) {
    // timer on
    if (soc >= 50) {
        // set relay on
        msg.payload = 1;
    } else {
        // set relay off
        msg.payload = 0;
    }
} else {
    // timer off
    if (soc >= 50) {
        // set relay off
        msg.payload = 0;
    } else {
        // stop further processing
        msg.payload = null;
    }    
}
return msg;

Relay-Timer_Flow.txt
Hi

I just rebuild the flow from your input.
It does switch Relay 2 On at timer event and Battery SoC.
Nevertheless it does not switch Relay 2 Off; regardless of timer state and/or SoC.
Did i miss something ?

Node-RED flow is attached

Hi

since the flows are driven by state changes i struggled to have a working flow to set the Relay 2 Off at a certain SoC.

currently i have setup an inject node as "Timer On" to a function node which is setting the message payload to 1 at >= SoC. If SoC is not met message payload is 0.

To switch Relay 2 Off an another function node is setup in interval mode to have the state pushed every minute and check against SoC to protect battery from low discharge. It keeps Relay 2 On as long as Soc is >= xx; while Relay 2 Off when SoC < 30

Maybe someone has a more elegant way to accomplish the same functionality ?

SetRelayOn

var soc = global.get("StateOfCharge");
if (msg.payload == true) {
    // Timer On
    if (soc >= 90) {
        // Set Relay On
        msg.payload = 1;
    } else {
        // Set Relay Off
        msg.payload = 0;
    }
}
return msg;

SetRelayOff

var soc = global.get("StateOfCharge");
if (msg.payload == false) {
    if (soc >= 30) {
        // Set Relay On
        msg.payload = 1;
    } else {
    if (soc < 30) {
        msg.payload = 0;
    }
}
}
return msg;