I vape using a sigelei 150 watt box mod and normally use my lg 18650 batteries. With radio shack closing near me, i couldn't help but purchase 2 18650 batteries for only $7. The packaging says its for use on devices that require high power for short periods of time which imo sounds like vaping needs. I'll post the exact product info when i get home. All i know on the top of my head is they are li ion 2000mah with protection . My question is, would this be a safe option to use as a backup if my primary batteries fail me? My charger is a D4. Any info helps thanks in advance!