Pretty normal for most of these action cameras that run high res and fps. The Mini has a 1500 mah internal battery so based on the size of a USB battery pack you should be able to ballpark run time..

I have a 20K mah and a 10K mah battery pack and I'll prob run the 10K in my saddle bag. Counting the internal battery, that will give me about 11500 mah of total battery life or somewhere close to 6 hours at 4K 120FPS.. If I ran the 20K mah then double that..

Consider that is running 4K and 120 FPS. If I were to run lower settings then obviously I'd get more run time. Most of my rides are easily under 6 hours so I'd just need to change the battery pack nightly.. USB battery packs are pretty cheap these days as well...