I was told I could run this stove on battery power rather than plug in to an outlet. However, batteries were dying after a few days even when I didn't actually use the stove. The seller was finally convinced to exchange the battery unit. Now I'm up to maybe two week life for the batteries (and that's only using the stove on occasional days, and only for a few hours at a time). Question: do you use this stove on batteries? And what battery life are you getting?