It’s very simple. I just took some wood, and formed it like 4 batteries. Drilled a hole and attached two screws on the wires. Just be sure it can move in the holder so the spring will push the fake batteries to the contacts.
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I have one basic question: I am using rechargeable batteries (NiMH), they last for more than 2 months with 4 people using the main door 10-20 times per day.
It doesn’t really bother me if I have to change the batteries at such low frequency, I wouldn’t spend the effort with a fixed power supply.
What is your motivation?
Hi @ueffchen, my motivation was that batteries where draining in a week and that was not only because of Nuki but also because another api is controlling the state of Nuki. So i want to avoid empty batteries and for this investment in an adapter is cheaper then rechargeable cells.
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Hi @fvhuizen, why do you poll the Nuki?
I poll the bridge which is connected to power and caches the state of the Nuki if I am right.
And where do you think the bridge is getting the information from 
1- Using a power adapter with Nuki looks feasible as was nicely shown by @fvhuizen
2- I expect that a new firmware version may have an option to make Nuki know it is working with a power adapter instead of batteries.
3- In this way Nuki would not be sending warnings regarding low battery.
Hey there, anyone using a power supply for while to give any feedback, please? I installed a Nuki 2.0 recently and am already anticipating possible improvements I can make to reduce failure points. Thanks.
We are using Nuki on a frontdoor, with 4 people using Auto Unlock and Lock Operations frequently.
I would guess we have 10-20 operations per day, depends on weekday, school vacation etc.
I have a number of rechargeable NIMH batteries at home - from Ikea, Panasonic, Aldi… - I just use the one that is charged, never care about which one to use. The batteries usually last several weeks, I guess 6-8.
The warning is pretty reliable, we have never faced a situation where the Nuki didn’t operate anymore.
My personal take is: before starting to mount a cable on a moving door, with a power supply that has to be always connected, I stay with batteries.
Thanks @ueffchen, I have got two sets of eneloop and will give it a go. I’m just very conscious of battery usage and reliable notifications that I’ll always think on alternatives to eliminate single point of failures.
I also made this mod, slightly different “batteries” used. Batteries on the nuki app were lasting a week or 2. And the last thing I ever want to do is replace batteries when I’m in a rush to leave the house. Fitted to a pvc door, so now to get creative with hiding the wires 
Hi Nuki forum users,
I am also trying to eliminate the battery dependency for the Nuki 
I have an older (big block - non stabilised) adapter with 3, 6, 9 and 12 volts max 2 amp. I tried the Nuki with the 6 volt setting.
What occurred to me was that the led ring on the Nuki (that i have set to be on the lowest brightness setting) was suddenly very bright. Regardless, the bright led, the locking and opening operations went very well.
When I went into the battery settings and checked for the debug power details i saw the big power block almost delivers 9,2 volts (see screenshot) in idle mode to the Nuki. Quite high…
For now I disconnected the power supply and went back to batteries.
Would it be be OK to power the Nuki for a prolonged time with 9 volts idle power or would i slowly but surely kill the Nuki??
Any recommendations are highly appreciated.
As i m not allowed to post more then 1 image in my first post i post a pic of the power adapter in a follow up post
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This is the simples not stabilized power adaptor. Idle voltage can be much higher than you have set. It achieves around 6V only under nominal load (2000mA in this case) and still it will be very unstable.
You cah kill the nuki and any other device easily with it.
Try to use 2A 5V usb adapter (4x rechargeable batteries has 4,8V).
Deadlifter, why don’t you use rechargeable batteries with a charging adapter. In case of a power outage the doorlock will still work.
I also recently replaced the batteries with a 5v powered “dummy battery pack” which seems to work really well.
It fits into the existing battery cradle without any modifications needed. The wire from the battery is a flat cable, so it fits snugly within the battery cradle and main housing joint . If your mains power supply is not close to the door, then you may need to extend the power cable extension (1,8M) that comes with the pack (or just buy a longer extension cable). Even though the power supply rating is only 6V-1000mA it seems to work fine. Nevertheless, I probably need to load test it for a few more weeks to be totally sure.
https://www.amazon.de/gp/product/B07Q1KTXFR/ref=ppx_yo_dt_b_asin_title_o00_s01?ie=UTF8&psc=1
Your Nuki received >9V only because the power supply (psu) is not stabilized psu and deliver higher voltage than is marked on the selector. Just lower a step to 3V and you probably get 5 or 6V. If you’ll use a stabilized power supply, even a smartphone power battery charger (5V/2A) you’ll see a right value.
I’m android Nuki user and I’m wondering how you get such info about battery as shown in posted picture? Because my Nuki app doesn’t show such informations, that screen is not available. Maybe you make some light for me 
Thank you.
In Administration/Battery tap 7 times on the info text in the middle of the screen.
Thank you. I found also the thermometer feature:)
Hoe weet je wat de plus en de min is in de nuki?
gr