RTLS tag battery life depends mainly on how often the tag reports its position and which radio it uses. Safety tags worn by pedestrians report many times a second so that a forklift can react to them, which drains the battery quickly and usually means a charging routine built into shift change. Asset tags that report every few minutes, or only when they move, run far longer on a replaceable cell. Ultra-wideband ranging draws more power than Bluetooth Low Energy beacons. Vendor battery figures assume a specific update rate, so ask which rate the quoted life was measured at.
Battery life is an operating cost and a safety question at once. A pedestrian tag that goes flat mid-shift makes its wearer invisible to a tag-based system, so check whether the tag warns the wearer and a supervisor before it dies, whether charging racks sit where people collect and return tags, and whether the system reports which tags were not charged. Tags on forklifts can often draw power from the truck instead of a battery. The RTLS overview covers anchors, tags and update rates, and safety system maintenance covers the routines that keep tags working after go-live.