K8 Pro Battery Replacement: Fixing My Keychron Keyboard
My Keychron K8 Pro has been my daily driver for a while now, and lately I noticed the battery just wasn’t holding up the way it used to. The capacity had dropped to just 2 weeks and I was charging it far more often than I’d like. I’m definitely not going to replace the whole keyboard, so I decided to do a K8 Pro battery replacement myself instead.
What’s needed
Here’s everything I thought I’d need: a screwdriver kit, a spudger for prying, a keycap puller, a JST ZH connector kit, a wire cutter and crimper, and the replacement battery itself.
Turns out I got ahead of myself here. I only realised partway through that I didn’t have the right crimper for the connector pins I’d bought. More on that later, it ended up not mattering much.
Which battery to purchase for the replacement
I went with the exact same specifications as the original battery. It is a 606090 lithium polymer battery with a JST ZH 1.5 connector. You can find a bunch on Aliexpress like this one here. Amazon also has some listed like this one. Some might come with connectors that may not fit the keyboard directly, but it’s a simple soldering or refitting fix if you have a JST ZH connector set.
K8 Pro Battery Replacement: Disassembly
Just after 2 weeks of minimal use, you can see just “2 bar” of battery capacity remains. So yes. I definitely need to replace the battery.
First up, I need to remove the keycaps where the screws are on the keyboard’s PCB. But as I was popping off the keycaps, it revealed how much dust has built up under there over time. Since I already had everything open, it felt like the perfect excuse to give it a proper clean rather than just doing the battery swap and closing it back up. A quick vacuum around the switches got rid of most of the dust and lint that had settled in.
With the keycaps off, the screws were exactly where Keychron says they are in their official disassembly guide. Worth bookmarking that page before you start, it saved me from guessing.
I quickly realised that I also needed to remove the side bezels of the keyboard casing. Remove the 4 screws using the hex key that Keychron provided along with the keyboard. The side bezels prevents you from lifting the PCB off the casing. Once you removed the left and right side of the bezel, the top and bottom ones would slide out.
Once the screws were out, I could lift the top case away from the bottom. Inside, there are a couple of cables connecting the two halves, the battery cable and the daughter board cable. I went slowly here and unplugged them carefully rather than yanking the case apart, since it’s easy to strain or tear these if you’re not paying attention.
Replacing the battery
The battery sits under the rubber gasket of the keyboard. It’s hard to miss 😀. Remember to remove the connectors before you proceed further.
1. The old battery was glued down more firmly than I expected
Getting the old battery out was the trickiest part of the whole job. Keychron uses a pretty strong adhesive patch to hold it in place, and it did not want to budge. I ended up sliding a plastic card underneath to gently work it loose. I’d avoid anything sharp or metal here, a screwdriver or spudger tip can easily puncture the battery cell if you’re not careful, and that’s not something you want to deal with.
Worth noting, my old battery wasn’t swollen or puffy. It came out looking basically fine. It had just lost enough capacity over time that it couldn’t hold a decent charge anymore.
2. The case has a specific spot for the battery
Once the old battery was out, I noticed the keyboard case has a marked outline showing exactly where the battery is meant to sit. It’s also worth sticking to the same battery dimensions if you can, mine was a 606090 size, because the internal gasket has a compartment moulded specifically for that footprint. A different sized battery might not sit flush.
3. Matching the connector meant reusing the old wiring
The new battery came with bare wire ends rather than a matching connector, so I needed to connect it to the board somehow. I confirmed the connector on the board was a ZH1.5 pitch, which matched the pin and housing kit I’d bought. Except, as I mentioned earlier, I had the wrong crimper for it.
Rather than wait on ordering the right tool, I cut the connector and a length of wire off the old battery and soldered it directly onto the new battery’s leads instead.
Setup (Reassembly)
With the wiring sorted, I set the new battery into its marked spot in the case. I used one of those clear silicone double sided tape to stick the battery down to the casing.
I reconnected the battery cable and daughter board cable, then did a quick test before closing everything up. The switch LEDs lit up as expected, which was a good sign everything was wired correctly. It’s also showing the battery providing roughly 80% of the 4000mAh capacity
From there it was just a matter of putting the case back together, screwing it shut, and pressing the keycaps back on.
Final Thoughts
This K8 Pro battery replacement ended up being a pretty straightforward repair once I got past the sticky battery adhesive. If you’re doing this yourself, follow Keychron’s official disassembly guide for the screw locations, take your time unplugging the internal cables, and use something plastic (never metal) to pry the old battery loose. And double check what crimper you actually need before you start, unlike me. Or just use a soldering iron and save some money on the crimper and JST ZH connector set.
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