hi .. just a question .. when you say burn out the coils... do you mean the coils burned and broke and disconnected . . . like the filament in a light bulb or a fuse breaking or do you mean getting a burned taste?
What I do to save tons of money is rinse off the heads, soak in water over night and dry the next day on a paper towel. I change heads every refill, which is often considering I'm using a mini pro tank II, and Kanger Evods. Every couple of weeks I change out the flavor wicks and burn the gunk off the coil without replacing the coil. I use some boiled cotton embroidery thread, 2mm and have had excellent success for two months. Three tanks changing through 7 heads total. Either I'm really lucky or others have had horrific luck. Knock on wood, I haven't destroyed a coil, yet only gunked them up and had to clean them with a good dry burn.
If the coils actually burned out like a light bulb filament... I'd definitely test that battery.
Blessings and Joy on your Journey,
Bliss