Pro tip: Charge your intervalometer before a long drive for night sky pics

I drove out to the desert to photograph the Milky Way arch last summer. Got all set up as the sun went down, then my intervalometer battery died right away. Spent the whole night hitting the shutter button every 30 seconds by hand, and I almost missed a cool shooting star because I was rubbing my cramping fingers. What's your worst gear fail while trying to get astro shots?