>>326655074
Why? Just get lipstick sized powerbanks and some velcro, for +8 hours.

Or 18650 battery and enclosure like this https://www.aliexpress.com/item/32847884771.html?spm=a2g0o.productlist.0.0.43096f63xmkV1c&algo_pvid=5db7ce60-1076-427e-8e3b-d6dc7404f837&algo_expid=5db7ce60-1076-427e-8e3b-d6dc7404f837-2&btsid=2100bb4c16147910044591889e0af2&ws_ab_test=searchweb0_0,searchweb201602_,searchweb201603_

which both are dirt cheap.