We took those fans and I don't recall changing the batteries more than once for the entire trip. You don't keep them on all day or anything, and you only use the batteries when you press the on button.....which was mainly just in hot lines for us. The bigger problem that I have with that fan, is that the batteries fall out easily, our compartment never stays shut well - hope that yours is better, or I would pack a bit of electrical tape or something to keep it shut