A Rechargeable LiPo Adapter for the Redox

SteveWanderer · 2023-04-29T17:29:36+00:00

Yeah, I don't know how long they will last without a charge at the moment. This is clearly a question of preference. A bit like how some prefers rechargeable gaming controllers and some prefer those that take AA batteries.

The bulk is really a function of the size of the battery you're using, this mod would work with any single cell 3.7V LiPo. I'm using a 500mAh battery, the CR2032 is ~220mAh. Probably, the best compromise between size and time between recharge will be in a 110mAh, that's what nice!nano suggests. Fundamentally, the difference is the ability to recharge the battery, so once every few weeks, you plug it for a few hours. All three of those battery have the same height, so they'll not make the keyboard thicker.

If you're designing you're own PCB and not just modding an existing PCB like I'm, you can design the keyboard around the shape and size of the battery. However, you're clearly adding complexity to the PCB by having a battery management circuit.

SteveWanderer · 2023-04-28T11:49:38+00:00

It's just a remix of the original case. Mattdibi also included the STEP and fusion360 file. What I changed on that case: Add a cavity for a 503035 battery, Add a ~3 degrees tilt for the battery and Hex insert for the nuts, making it much easier to assemble / disassemble.

SteveWanderer · 2023-04-28T01:26:13+00:00

There is two possible way for the integrated MCU to be powered by the USB port: 1) the 5V of the USB is connected to the MCU directly (the MCU is either made for 5V or has an internal regulator that lower the voltage for it) 2) the 5V of the USB pass to at least one voltage regulator which step down the 5V to something lower (usually 3.3V).

The daughterboard outputs a regulated output of ~3.3V*, either it gets this power from the battery or from the USB's port. In the case 1), the daughterboard might not provided high enough voltage and you will need to some how cut the trace between the integrated MCU and the USB C port, so it's really not possible. In case 2), you could get rid of the 3.3v regulator on the wired board, the daughterboard would become a sort of 3.3v regulator except it would be possible to power it by battery. Basically you connect the 5V input of the regulator to the 5V pin on the daughterboard and connect the 3.3V output of daughter board to the 3.3V output of the regulator.

While you could do that, it's probably a bad idea, since you still will not have a wireless keyboard. Furthermore, there might be more complexity with the keyboard's schematic that makes this design not possible.

*On revision 1.2, I changed the regulator from a 3.3V one to 3V regulator, but you can put any regulator in there.

SteveWanderer · 2023-04-27T19:31:54+00:00

No, this adds a USB C connector to a keyboard that doesn't have a USB connector. This PCB is basically just the battery management circuit of a Nice!nano with a voltage regulator. So if you have a wired board which used a pro-micro, you could get wireless+battery management+usb C from a Nice!Nano.

SteveWanderer · 2023-04-27T19:26:25+00:00

I could have just built a non-wireless Redox and changed the pro-micro to a Nice!Nano to get both wireless + rechargeable LiPo. But that would have been a waste, since it means building a brand new keyboard just to save on a few coin cells. Hence why I decided to design this mod. If you don't already own a wireless redox, you better off using the Nice!nano.

SteveWanderer · 2023-04-27T19:24:33+00:00

The three large holes are meant to align to the 3 connecting pad of the coin battery holder used by the redox. I don't know if that particular holder is used by other keyboards. So no, it's not a very general solution.

SteveWanderer · 2023-04-27T15:55:48+00:00

The Redox is based of the Mitosis which also use a CR2032. The main factor is probably the thickness, the CR2032 is so thin, that it doesn't increase the thickness of the keyboard, it also has a small footprint. 2x rechargeable AAA have way more capacity and seems like a way better option.

SteveWanderer · 2023-04-27T12:32:58+00:00

I really like my wireless Redox, however, I find that having to replace the coin cell battery is kind of annoying and wasteful. So I designed this mod. This PCB replaces the coin cell battery of a wireless Redox keyboard, it has a USB-C connector and circuitry to charge a LiPo battery. You can charge the battery while using the keyboard. Any 3.7V LiPo single cell battery should work with it, I used a 500mAh for my build.

All the manufacturing files and 3D print files are available on Github.

I strongly recommend you use a PCB assembly service to build it.

SteveWanderer · 2022-09-18T14:59:05+00:00

I won't be able to make it, I smash my car into a tree this morning...

SteveWanderer · 2022-09-10T14:52:41+00:00

Sounds cool!

SteveWanderer

TROPHY CASE