Shelly 2.5 sending constant signal to both SW ports?!

    Hi Shelly experts,

    I am new here and trying to troubleshoot issues I have with my new Shelly 2.5.

    It is sending constant signal to both SW ports.

    When measuring voltage against null (N): SW1 has 220V, SW2 has 160V

    When measuring between two SWs it is 60V.

    When connecting them to double (1-0-2) signal switch, which I want to use with it to manage my roller shutters, only one direction works - when signal is sent to SW2 (160V) because obviously there is some voltage diff which it can notice.

    Other signal is not registered by shelly at all.

    Both output ports seem to be working fine, I am getting nice clean signal on both of them when using app, just getting no reaction when pressing signal switch.

    Is it possible that it tries to switch on N signal somehow?

    I tried both roller shutter and light modes, also few firmware versions.

    Tried also with and without SW and Output wires boeing connected. Also with only 1 L input (Shelly 2.5 has two L inputs). Always the same result.

    Also tested Input and SW of Shelly for short circuit (with multimiter buzzer) but no, no short circuit seems to be.

    Shelly is really powering both SW inputs itself and with different voltage!

    Any ideas what I might be doing wrong or I just got defective device?

    Thanks for any info and help.

    Best,

    Igor

    You should read the same voltages between terminals SW1 and N as between SW2 and N! Depending on the input resistance of your DMM, it should be about 130V AC in both cases. I assume a faulty Shelly 2.5. If you want to measure more precisely, put the suspicious device at your desktop and supply it with mains voltage (terminals L and N). Switch your DMM to DC voltage! You should read about 3V DC between terminal SW1 and L (positive pole at SW1). The same voltage should to be measured between SW2 and L. Any deviation are signs of a defective device!

    „Habt Geduld. Alle Dinge sind schwierig, bevor sie einfach werden!“ (aus Frankreich)

    „Nothing in life is to be feared, it is only to be understood.“ (Marie Curie, 1867-1934)

    „Es reicht nicht“, rief Schiller, „Gedankenfreiheit zu fordern, man muß auch denken können, sonst fordert man Gedankenlosigkeitsfreiheit und die ist die Freiheit zur Dummheit, welche wiederum die schlimmste Unfreiheit überhaupt ist!“
    (Aus „Besuch aus Weimar“ von Gert Heidenreich, Schriftsteller, *1944 in Eberswalde)

    Thanks a lot for your quick reply. It was very helpfully!

    I did some more testing and in the end got another shelly 2.5 to compare. Unfortunatelly I have no test bench to test it properly with DC input, but:

    With AC 230V input and no wires connected to any SW or O ports, I also get 130V between N and SW1 / SW2. Issue starts when I connect my wires to SW ports. It seems that 130V signal sent to SW is so weak that simple wire resistance is causing issues for it, as my SW wires are 7m long and having 3 wago connectors on each SW wire (7m distance from switch to shelly ). When I mount shelly just next to switch (SW wires are 10-15cm long), it behaves fine. As soon as SW wire is longer and having wago connector on it, no way, it just switches N-SW voltages to 160V/230V. I am guessing that SW signal sent by shelly is so weak it is disrupted with smallest wire / connector resistance.

    When trying with new shelly I got - works fine from start with full 7m legth of SW wires. However voltages with SW wires connected are 80V and 110V AC.

    Is there any specification telling how long SW wire can be and should I send my Shelly back to shop as defective?

    Thanks.

    I’m not aware of any specification about wire lengths at SW input. Contact resistance should be neglectable, cause the current necessary to activate a Shelly SW input is very small (34μA DC). Thus, contact resistance of some 1000 Ohms should not play any role. However, in the perspective of interference voltages or currents, disturbances are possible.

    But at the end of the day, you should return your faulty Shelly if another device is working perfectly in your premises!

    „Habt Geduld. Alle Dinge sind schwierig, bevor sie einfach werden!“ (aus Frankreich)

    „Nothing in life is to be feared, it is only to be understood.“ (Marie Curie, 1867-1934)

    „Es reicht nicht“, rief Schiller, „Gedankenfreiheit zu fordern, man muß auch denken können, sonst fordert man Gedankenlosigkeitsfreiheit und die ist die Freiheit zur Dummheit, welche wiederum die schlimmste Unfreiheit überhaupt ist!“
    (Aus „Besuch aus Weimar“ von Gert Heidenreich, Schriftsteller, *1944 in Eberswalde)