SAFETY ALERT Shelly 2.5 / shutter control mode / stuck contact

Hi folks,
unfortunately I need to raise a SAFETY ALERT on Shelly 2.5 devices, especially when operating in shutter mode. As for the nature of the fault, this problem can also occur in any other operating mode of the 2.5.

Fault Description:

  • On of the two alternating contactors (in my case for OPEN direction) was sticking.
  • Contactor provided continuous power to the OPEN output terminal
  • Motor always moved upward until end microswitch switch stopped
  • Fault not shown or detected by device
  • Device Reboot and power cycle made no difference

Fault detection:
Shutter on command “close” went down 10cm.
As soon as the open end microswitch came out of his mechanical dead band, shutter stopped due to overpower (set to 180W).
In this moment, the motor was simultaneously powered for “open” and “close”, having two forces electrically and mechanicall work against each other.
Continuous power on “open” terminal made shutter open again.
Measurements to reveal this: Check with voltage meter on continuous power on one of the output terminals, irrespective of input switches or SW commands

Root cause:
Sticking contactor in Shelly 2.5, providing continuous power to one output, independently of actual control or commands.
Stuck contactor NOT detected by Shelly, power not measured, always reading “0 W”.

Operated shutter motor:
Nobily P4 13/14-40. 3-wire plus earth (open, close, neutral)
Nominal Power ~125W, way beyond the 10A / 2300W a Shelly 2.5 can handle per channel

Have you contacted Shelly support?

1 Like

No, not yet. Will do that when I have more time, of course.
Has been filed with identical description, now.
For the moment - and given the possible impact - I decided to raise this topic here first.

One failure out of tens of thousands or more isn’t really a “safety alert”. It’s a warranty claim. These things happen.

Yes, these things happen.
Nevertheless the consequences can be drastic even in one single case, talking of overheating motors and subsequent fire. Some users use current or power detection to stop at the end of the cycle, which would have failed.

I have had 2 Shelly 2.5s have the sticking on relay, Shelly did replace them under warranty no problem.

For an out of warranty one, they gave me 30% off the new Shelly 2pm plus

1 Like

A quick search on their support FB page (ew) reveals that this seems to be a rather common problem with the 2.5 and it has been going on for a while. Shelly seems to replace them for free if you raise a ticket. And yeah, that is a pretty serious fault. Looks like they have a quality problem with the relays they use. The relay is not the part to save money on.

People do that ? :open_mouth: That’s a terrible idea.

1 Like