Trådfri Remote Battery Life Expander

Intro

This is an adapter case for the IKEA Trådfri Remote.

The original remote has a notoriously short battery life, due to using a coin cell CR2032 battery. This adapter replaces that with a CR123A, which has similar behavior (discharge curve), but much larger capacity, and adds a physical battery switch. If you only use the remote rarely to e.g. adjust the brightness or color temperature, turning it completely off when not in use extends its battery life further.

The Trådfri Remote has been largely discontinued by IKEA and is only sold in Bahrain now, apparently. It was replaced by the Styrbar Remote which, more practically, uses two longer-lasting AAA batteries instead of a single CR2032. Still, there are likely a lot of the older model around which can still be useful with a larger battery. Therefore this upload.

The current design uses a good deal of additional hardware, which makes it harder to build one, but some of it is optional, the original FreeCAD model is provided for modification and adapting to your own hardware, and suggestions for improvements are welcome in the comments.

Disassembly

The rebuild has to naturally start with disassembling the original remote, which is somewhat non-trivial for the original model, and is harder for the updated one. However, Per Mejdal Rasmussen made a video walking through the former, and an update for the latter. The crucial fact to know, apart from the location of the snap hooks (shown in the video), is that this is not the typical cantilever snap fit, where you have to push inward on the white hooks under the buttons, but instead outward, on the gray case. The hooks are made of very rigid plastic and won't bend, while the case is made of a softer ABS+TPU blend and, although still quite tough, bends better. Once you get the remote apart, don't lose the rubber reset button insert, you can put it into the new case.

Hardware

The hardware used by the build is shown numbered in one of the photos:

1. Sticky copper foil tape - often used for PCB repair, shielding, or stained glass work. Only needed if you want to print and build the (fiddly) CR2032 adapter. You can solder the battery wires directly to the remote's PCB instead.
2. Stranded wire for connecting the battery (and optionally the switch) to the remote's PCB (directly or through the CR2032 adapter)
3. M3x8mm sunk head machine screws for fixing the back lid to the case. Required, but doesn't have to be hex socket, obviously. Screwed into the #8. M3 heat set inserts.
4. 8x8mm self-locking push-button switch to control the battery connection. Sets of these can easily be found on e.g. AliExpress. The mechanical drawing of the exact used switch is attached. Optional, you can connect the battery to the PCB directly. In that case you'll need to either modify the model to remove the button hole, or to print the button in the same color as the case and glue it in. And, of course, you could modify the model to fit your switch.
5. Keystone 289 negative AA battery contact. You can find them under this name in lots of places, and they're useful for multiple types of batteries, and can be used in your other builds. They're not the cheapest, but you will need to modify the model to accommodate a different type of contact.
6. Keystone 228 positive AA battery contact. Similar situation to Keystone 289.
7. 10x5x2 rare-earth magnets. Again, can be easily found on e.g. AliExpress under this name. However, these were simply the biggest I had, and they're not very strong and will only hold the remote on thick magnetic metal (e.g. particular spots on a fridge), or require some sort of rubber coating on the back. Optional, if you're planning to use the remote on a horizontal surface, or hang it using the keyhole slots and screws. Otherwise, again, feel free to modify the model for your own magnets.
8. M3x5.7mm heat set inserts - sold under this name and are required for fixing the back lid to the case, along with #3. M3 screws.
9. M2x6mm sunk head machine screws - used to fix the switch holder to the case. Not necessary, if you're not installing the switch, or even if you do, because the back lid will likely hold it in place well.
10. M2x4mm heat set inserts for the #9 M2 screws securing the switch holder. Not necessary under the same conditions.

Printing

PETG is recommended for the case, as its snap fit springs around the remote need to be flexible and not break when assembling. The rest can be printed from whatever. Layer height can be 0.2mm, but 0.1mm is recommended for the button and the CR2032 adapter. The latter doesn't need to be printed, if you plan to solder the battery wires directly to the PCB. The switch holder doesn't need to be printed either, if you're not installing the switch.

The case needs to be printed upside down and with supports under the big round opening for the remote to ensure the ridge and the springs print right.

Example Slic3r project trådfri_remote_project_example.m3f is attached for reference.

Assembly

1. Install the heat set inserts.
2. If installing the switch, solder two (negative) wires to its appropriate pins (test with a multimeter, or refer to the photos), and thread them through the switch holder. Consult photos for the exact routing. Test for full insertion.
3. If installing the switch, solder the shorter wire coming from the switch to the negative connector.
4. If not installing the switch, solder a wire to the negative battery contact.
5. Solder a wire to the positive battery contact.
6. If building a CR2032 adapter:
   1. Cut strips of copper foil somewhat longer than the adapter diameter
   2. Pierce their middle with an awl or a thick needle
   3. Strip about 2mm of the insulation off the two wires, but don't tin them
   4. Thread the stripped ends through the back of the holes in the copper foil
   5. Bend to 90 degrees, and spread the threaded wire strands in a circle on top of the foil
   6. Solder the wire strands with minimal amount of solder
   7. Tear off copper foil backing
   8. Thread each wire through the corresponding side of the central opening of the adapter and out the side opening
   9. Spread each of the pieces of foil on their corresponding contact surfaces, cut off the excess
   10. Push the soldered areas of foil somewhat into the central opening to comply with CR2032 thickness requirements.
   11. Install the adapter into the CR2032 battery holder. Be careful to pull the spring steel hooks away from the adapter to not tear the foil when inserting.
7. If not building a CR2032 adapter, solder the remaining wire ends to the corresponding contacts on the board. Observe the polarity!
8. Carefully insert the remote PCB into the round opening until all springs click into place. Align the two snap hooks with indentations to the springs with corresponding bumps in the middle. Make sure to install it so the remote's power button is the right way up.
9. Install the battery contacts.
10. If installing the switch, push in the holder with the switch inserted and the wires threaded through, and the button installed onto the switch stem. Optionally install the M2 screws.
11. Insert the CR123A battery. Observe the polarity!
12. If installing the magnets, use CA glue to fix them in the recesses in the back lid.
13. Insert the rubber reset button from the original remote into the back lid.
14. Slide the top end of the lid into place, push in the bottom, and install the M3 screws.

That should be it. Don't hesitate to suggest improvements in the comments!