Update: Added a low profile version for that sweet floating keycaps look :)

A modification to my previous design, this facilitates the upgrade of the standard 1800mah lipo battery to (up to) 3x 18650 cells.

If you're after a replacement standard case, see my original version.
Or this minimal low profile version.

You will need a basic understanding of electronics and basic soldering skills to perform this upgrade.

1. You will need to use the connector from the original battery if you don't have a spare.
   Just cut the connector off and make sure to tape up the wires on the original battery so it doesn't accidentally short itself out.

2. Route the connections and connect the batteries up, I did it while the batteries were in place, but you could remove the dividers and put them all in in one go.
   Just make sure that the battery terminals cannot be bridged, otherwise it'll end badly!

3. Wire the batteries in parallel, otherwise you will kill your keyboard!
   See here for more info: https://zbattery.com/Connecting-Batteries-in-Series-or-Parallel

4. Secure the batteries down (I used double sided tape which is working so far).

Any modifications are obviously undertaken at your own risk, what works for me may not necessarily work for you first time, or every time.

After that, enjoy your tripled battery life :)