How can I disable the low-battery sound in Cyanogenmod?
As per advice from Narayanan, I replaced /system/media/audio/ui/LowBattery.ogg with another .ogg file. The next time it was triggered, the new file played.

I then tried placing an empty file at /system/media/audio/ui/LowBattery.ogg, but this did not work.

Finally, I downloaded a slient .ogg from here, placing it at /system/media/audio/ui/LowBattery.ogg. This worked perfectly.