I ended up getting a second one of these. . .
10000mAh Oscillating Battery... https://www.amazon.com/dp/B099558734?ref=ppx_pop_mob_ap_share
TBH Ive never used the battery on either one I’ve just popped the battery out and run a cord directly into the fan and like I said I got a second one
not cheap but worth the money.
Removable 10000 mAh battery, with a USB extension cable you can plug it into any power source. It moves a good amount of air on low and the battery lasts a long time at that level.