How to charge a gopro with no electricity?

So, i am going elk hunting up in the mountains here in a couple of weeks and i only have two bateries for my gopro(hero 4 silver). I wont have access to elecrricity because we are 30 miles back. But i could carry batteries. So i guess what im asking is it i can somehow charge my gopro with bateries or idk. I just want to do like a overnight timelapse of the stars without my gopro dieing. What do you recommend? -Thanks!

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