I had mine at a race this past weekend as well. I only raced in one class, so not as much use as I would normally have on a radio, but same experience, all day long, practice, qualifiers, and mains, the built in battery lasted the whole time. The graphic for how charged it is didn't even drop, never even took the external out to use it.

I did however take the external out to show people, cause everyone wanted to see it, hold it, everyone loved it, and we're pretty impressed it was a flysky.