Nifty! What is the power output of your radio?
5W - typical of most Ham HTs. Keep in mind that many mobile and home base stations are 45-50W. However, I belive under the right conditions, up to 1.5KW can be allowed. And that's not counting military and other users.
If I'm understanding, 446Mhz was the frequency that shut the bands down, right?
Yes. I strongly suspect it's not the optimal frequency, but with enough effort, it's one that works. I'll have to go back and try a few other frequencies.
Fascinating that 223Mhz did nothing!
I suspect the issue is that the cable between the two halves is acting as an antenna. The wavelength of 223 is too long for that short of an antenna to be effective. However, if I can find a more optimal frequency, that may change. I was curious that I couldn't affect the "Large" band on display. It could be component tolerances, but I'm suspecting the longer "antenna" shifted the frequency away from what I was using.
Anyway, I'm seeing in other threads where users users are reporting the Band shuts down, but when revived shows plenty of battery left. This could be the explanation for some of them.
As for a fix - I don't know. My guess is that the RF creates noise on the battery voltage sense. Ideally, a bit of filtering (like a small capacitor) would fix the problem. I'm not sure if it can be fixed by re-checking the battery voltage before acting (software), but it might cut down the number of incidents "in the wild".