I found what I believe is a hidden feature in the Wii controllers.
A while back I noticed that some of my controllers, when I turned them on, would only blink 3 of the 4 LEDs while trying to connect. “Weird,” I thought, “Maybe one of the LEDs is burned out.”
I ignored it until I spoke with support (about my green pixel problem), and the rep said it’s normal, but didn’t expand as to why.
Today I turned my Wiimote on and only two lights blinked. On a hunch, I hit the Home button and noticed the battery meter had only two bars – out of four.
So, apparently, when you boot up your controller, it will flash the battery life remaining. Neat. Wish I had been able to figure it out earlier.