Halogen Headlamp Troubleshooting

Greetings, all.

I don't intend to clog the forum - searches for answers were unproductive, largely due to the past HID headlamp issue. Please feel free to link to a past article and close the thread if applicable. Just don't be hard on me - I'm new here!
My 2008 Prius has been regularly maintained, no known system errors. 110k miles.

On to my issue. It has been very cold (~15-25 deg F) the last couple weeks here in Western Washington State. Late last week (Wednesday or Thursday?) my battery died in a parking lot, was successfully jumped, and on I went. Two days ago, my low-beam headlamps stopped working. I used high-beams to get home from work in the dark, figuring I would replace the bulbs within the next day or two. However, upon leaving work tonight, neither my high-beams or my low-beams turn on. The parking lights, tail lights, dash indicators (headlamp and brights) all turn on, just not the headlamps themselves.

Tonight:
I replaced the low-beam halogen lamps.
I checked the fuses.
I switched the headlamp relay with an identical relay from the box to see if the relay was defective.

Tomorrow, I plan on checking for loose connections along the harness.
Does anybody know what voltage/current I should have at the head lamp connector? What about at the fuse box?
Could it be an auxiliary battery issue?
Any other ideas?

Thanks much for all your help!
Zachary