Never give up on them until a couple days after an outage. I've had eggs resume and hatch normally after a day without power. Yeah you can lose some, but usually not all.
I would have liked to not give up on them, but didn't know what to do. My incubator was at 15 degrees, I thought about putting them on a heating pad, but my chicks are just recovering from shipping, and they have it. In the end, it is more important to me to keep my new chicks warm, then my new eggs warm. In hindsight, I realize the best thing to do was to go to town and get another heating pad. What was I thinking
