[EDITED for clarity]
Hi folks. For my next wireless split build, I’m exploring battery options for easy replacement while travelling. In this scenario, the battery’s reached its end of life and needs to be disposed of/replaced with a new one. However, it’s difficult to receive parcels or have access to a workshop while on the move, so the dead battery should be swappable without specialised tools, and the replacement battery should be easily sourced from any local hardware store.
For some background, this just happened to me. The LiPo in my current board was directly soldered to my nice!nano (bad choice, I know). Used the board on wired mode for a while, but the USB-C port became loose at some point due to accidental dragging and unplugging (I couldn’t find a magnetic USB adapter). Most local shops didn’t have the 3.7 V thin-ish LiPos that I often see in wireless splits, and language barrier made finding things difficult. Fortunately, I found a replacement battery (of dubious quality), but I want to make a dedicated battery slot in my next upgrade/build in case this happens again.
I know adding JST connector is an option, but the issue is, 3.7 V LiPos can be hard to find in some countries. I’m thinking of using AA or AAA-sized batteries (one-time usage or rechargeable type). Or use an RC LiPo (7.4 V?) but step down to around 3.7 V. Not sure what additional circuit or component would be required for this.
Has anyone tried to use such batteries for your split keyboards, or have seen a project that uses them? Also, if not AA/AAA-sized batteries, what other types and/or build would you suggest for this scenario?
(Photo from: https://www.dnkpower.com/lithium-polymer-battery-guide/)
While it may not be as common as 18650 or especially a AAA. A 14500 battery is as small as an AAA while retaining the same chemistry/voltages of normal lithiums you see used with a nice nano. Could be your best bet if you want small but easier to source/replace. An 18650 is your best bet on availability though, but they are huge compared to what we normally use.
AAA batteries operate at 1.5v nominal, so a nice nano would not be able to be powered by them/it would overcharge it.
True, I’ve been seeing mostly 18650s and only a handful of 14500s in the hobbyist shops where I travelled (South-East Asia). The latter was not crazy rare, still, so it’s a good candidate.
why not just use a JST connector instead of soldering it? What board are you running?
Sorry, just edited my post for more clarity. Adding a JST connector would certainly help, but the problem is I might not be able to find a replacement battery with the same JST connector while travelling in an unfamiliar country or region.
What about just using a USB battery? Would be more versatile since you’d also be able to use it for your phone, etc.
You mean like a mini power bank? Makes sense, since they’re indeed quite easy to find! Maybe I could use USB C instead of JST connection to power each half.
Building upon this. I’ve had the idea of making a leyboard with Qi charging coil at the bottom to charge it on my desk with no visible wires. They also make battery packs with a charging coil (or MagSafe for apple with the magnetic ring) could be an idea.
Yeah wireless charging would be really useful. It’s what I have planned for my next kb build. This could allow for smaller battery capacities to be used as well, since it’s easy to charge and reposition the kb halves while in use.
For other batteries ideas, there were some builds that used coin cells as batteries. For example this one: https://www.reddit.com/r/ErgoMechKeyboards/comments/11piaav/lütt_un_lütt_coin_cell_powered_bluetooth_split/?utm_source=share&utm_medium=android_app&utm_name=androidcss&utm_term=1&utm_content=1
Thank you! I considered the coin cell idea for a while, but the battery capacity looks a bit too small. Still, it has low footprint & is so easy to find :D
I would go the other way and pack a usb-c soldering iron…
Haha legit point! I definitely need one for as long as I still have to travel with my current kb, just in case more things break. I just learned of the Pinecil the other day, and it looks like the perfect candidate for a portable mini soldering iron.
Yes Pine il, TS80, or the bigger one TS100. All amazing options. Definitely worth having. Then a small roll of solder and tweezers and you’re good to go. (Sponge use wet paper towel)
I’m pretty good with batteries, but I don’t know if I understand the issue.
Isn’t the keyboard already rechargeable? If so then why isn’t charging it an option?
What are you using the keyboard with? How does that device get power?
Is recharging or using a power bank absolutely out of the question?
Are you looking for a temporary, semi permanent or permanent solution?
Are you strictly limited to common convenience batteries? How about slightly uncommon batteries like cr123?
When they say dying battery, I don’t think they mean discharging. They mean the battery has reached or is reaching the end of its life in terms of charge cycles and capacity
Couldn’t you use something simple like this? https://www.amazon.com/CACACOL-Charger-12V-1-5A-Parallel-Cigarette/dp/B07HNSDZ6K/ref=mp_s_a_1_3?keywords=aa+battery+powered+phone+charger&qid=1690650610&sr=8-3
Sorry, just updated my post for more clarity. Essentially, I found a temporary workaround (replaced that failed battery), and I’m considering a permanent solution for my next build/upgrade, which is to somehow power the board at 3.7 V with common batteries (AA, AAA or rechargeable AA/AAA-sized LiPos), or a power bank.
Not sure I 100% understand what you’re looking for, but for a while I used a pair of 16340 batteries with shields /charging modules. One of my installed lipo batteries had failed and at the time I didn’t know what I was doing with soldering. I attached the 16340 shields to the underside of my Corne and used them to tent the halves with ultra short USB-C cables to power my nanos. Sounds a bit hacky, and it wasn’t a pretty or permanent solution, but it actually didn’t look too shabby, and it was functional.
Ooh that was an interesting approach. Glad you got it to work. In my case, I just replaced the failed battery with a new, temporary one (of dubious quality), then patched everything together with some rough soldering work and electrical tape.
:) At the time, I didn’t even own a soldering iron, and I wouldn’t have known what to do with it if I did!
Repairing that battery myself later down the line was the first bit of soldering I ever did, which allowed me to then go on and build my first board.
If I’m reading you right, glad to hear you’re all sorted.
Nice job! Yeah, all is sorted out… for now xD There’s a chance something might come loose but at least I can access my tools back home soon-ish! Meanwhile, thinking how best to prevent this issue for my next build…
Felt like it might be worth sharing this: https://www.reddit.com/r/olkb/comments/1521gim/a_corne_with_aaa_batteries/
One good argument I saw for aa/AAA is that it can be hard to find certain lipo batteries and such in other countries. I think a more important thing is having a keyboard that can also work in wired mode over USB.
Thank you, this is exactly what I was looking for!
And yes, my keyboard did work fine on wired mode for a while (using ZMK), but because I had to constantly plug and unplug the USB C cable while transporting the keyboard over several months, the port became loose over time. Having a magnetic USB adapter could solve that problem next time.
That board can be found here:
https://github.com/sekigon-gonnoc/CorneECWL/tree/main
I believe he sells it online sometimes here: https://nogikes.booth.pm/items/2371017
I hope to see something like this, but compatible with the nine!nano. I don’t know kicad tho 😅
Oooh! I don’t know KiCAD either, but this is an interesting option to study. Thanks!
