|DIY battery for KX2|
You may be tempted to ask "Why spend $25 for a kit battery when $15 will buy one that's ready to go?"
The answer is that you're not only getting a protected battery, you're getting the ability to buy quality 18650 cells in the future without having to replace the protective circuitry.
In other words, you could use this battery as long as the no-name cells last (which, in my case, seems to be a good amount of time), then replace them with Tenergy, Sanyo, Panasonic or some other reputable brand for about $6 each. Just be sure to buy the version of these cells that doesn't have the raised button on the positive terminal.
This kit offers the way to replace your KX2 battery for about $18 without having to buy a whole new battery. After all, it's the cells that eventually wear out, not the circuitry protecting them. This also offers the flexibility to use 18650 cells of higher capacity such as the highly-rated Orbitronics (which actually uses Panasonic cells but see note below*) for a KX2 battery with 3400 mAH capacity.
Of course, this concept applies to existing KX2 batteries from Elecraft and Tenergy as well - replace just the cells, not the whole battery.
Another source to consider for a protected $33 battery with 3500 mAH capacity:
3500 mAH batteries
*A word of caution - not all 18650 cells are the same physical size. My generic pack is comprised of cells measuring 19.1 X 66.2 millimeters. This fits into a KX2. I have a variety of 18650 cells currently on order and will measure them with a caliper, check for fit in a KX2 and will post all that info here sometime around mid-January.