Connect Nuki Dooropener to Ac Outlet. No Battery Changing Anymore.

Maybe you have one of these Nuki door openers and also, like me hate changing batteries. Then these instructions can help you on the way to add a cable to it.
I looked for a way to do this with a way back, so although it involves some cutting and drilling the Nuki, you can remove the additions and go back to batteries if you want.

It might not even void the guarantee, if it brakes you can try to send it back without the battery case and back plastic cover.

This is absolutely no finished design, it will be possible to make improvements and simplifications. One can see this as a guideline and proof of concept.

I made two of them, and they do their job.

Tools used:

Small table saw

wire cutter and stripper

soldering iron

hammer

chisel

file

baby-saw

screwdriver

clamp

battery drill

Materials:

wire

6 volt net adapter, got mine for € 6,95

piece of wood

wire connector

This first step could be the hardest one, since I used a small table saw, you might not have. You can also chisel or file it, or use some pieces of plastic glued together in a shape that fits into the battery case.

It's a good idea to tin-plate the ends of all your cables.

Chisel a hole in the replacement battery packs to put a connector in. Hereby it is helpful to clamp the piece of wood between two other pieces or in a workbench to prevent splitting. Drill two holes for cables. I used short piece of speaker cable. A single copper strand cable didn't work. Roll the ends up a little.

Cut some pieces of the battery pack so that you can access the cables from the back, See pictures.

Hindsight edit: don't go through al this trouble and just drill a hole in the bottom of the battery cover for the cable. Much simpeler.

Cut holes as in pictures in back plate. This can be screwed off. The more you cut, the easier access, but also the more you weaken your dooropener.

The title says it. Take of the sharp edges to prevent cable damage.

At some point I had some problems taking the lock of the door again, because the battery cover got stuck. With this extra hole you can press the yellow release thingy without taking the battery cover off.

Attach a cable, you can also click the battery case/cover back on.

Stick the thing on the door. I ruined a cylinder with the three little screws provided, better use the two bigger screw holes on the side. Remember to give the cable some slack, so you can dismount it easier when needed.

Guide the cable to a 6 volt net adapter and a power outlet. Just try out the polarity, if it works, then you did it right, otherwise switch the wires. I hope you do a better job than me in hiding the cables, good luck!