Short Circuit when Opener Battery is dead

Hey there,

Unfortunately I had to witness my bell system failing yet again, when the Nuki Opener battery died. I have had to replace the Opener batteries four times within two years time - which by all means is more than fine. However, I was NOT notified about the batteries running low the last two times resulting in fully depleted batteries. This comes with a surprising caveat: When the batteries are completely dead, the Opener causes a short circuit in the A/B lines of the bell system. Hence, the system fails for all parties living in the same building (no bell, no intercom, no door opener).

The Nuki App was working fine at all times as I am also using a Nuki Smart Lock on a daily basis. For batteries I am using standard Varta AAA. The building has a Siedle system with the “Siedle In-Home-Bus”. Every apartment is equipped with a BTS850-02 handset.

Of course this could be prevented by replacing the batteries in time. But without a notification this poses a rather difficult task without wasting too many batteries. Either way, the system should not be failing if the batteries of the Opener are empty.

Is this supposed to happen, or am I in “luck” having bought a faulty unit?

Best Regards,


I experienced exactly the same. However, battery level indication has improved in the app. The only thing that is missing is a warning that this situation could happen

Is this on a bus or analogue intercom system?

Now I´m very happy, some months ago I suffered the same issue and I thought that my opener was broken or the cable installation cause the short circuit to me and the rest of neighbors. I´ll change the batteries and re install the opener.

Thanks a lot!!!

Thanks for your feedback, we are investigating this issue in order to provide a permanent fix.
Best regards

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I have the same question as David above - does this error happen on both analogue and bus systems, or just one of them?

In my case I have a Fermax 3311 ADS so I think it´s an analogical installation

Which wires are being shorted when the batteries go flat?
Would this short circuit also happen when the batteries are removed?

The Opener is designed in a way to not interfere with the intercom, even if batteries are removed. We are still investigating the edgecase of an unwanted shortcut with almost depleted batteries.

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Hey Georg,

It’s been a month. Do you have a status update on this?

Best Regards,

I think your system is a digital system? Maybe this issue only effects digital systems?

Any update on this issue?

I have the Same Problems With a digital Bus System
…Not funny.

Hi! I changed recently from a analogue to a digital bus system, and please say me, what are the symptoms of this, or what happens when batteries are going low! I want to look for this, to prevent any inconvenience what can maybe accur with this issue! Thanks!

the entire bell system in the entire house then no longer works


Oh man :flushed:! Thanks for the information, I will build tomorrow a permanent Power Source, for avoiding this at all! Very thanks!


Could you give an update on this? It happened to me too

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Yes, I’m curious to know details also on this as the whole building could go down.
Does it happen on certain batteries, rechargeable, alkaline?
Only on digital systems with bus or affects analog systems also?

I have just experienced exactly the same thing. Before my vacation, I was shown that the batteries are almost empty. So I installed new batteries. During the 3 week vacation the system failed in the whole house. When I got back and the technician was in the house, he identified the opener as the cause. I noticed that the opener was not available during the vacation. So, again, I suspect that the batteries were completely dead and that caused the short.

Same system: Siedle BTS850-02.

Would be happy if this problem is treated and solved with high priority.

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Today I had again the same issue, All the houses of my neighborhood down. I´m going to change to a usb power. My System is analog