Always use fresh alkaline batteries for live performances. While rechargeable batteries can be used, alkaline batteries offer significant advantages. In addition to a longer operating time, the major difference becomes apparent when performance begins to decline. With rechargeable batteries, there is a sudden drop in performance due to their discharge characteristics. The operating voltage cannot be maintained. In contrast, the voltage of alkaline batteries gradually decreases, allowing time to prepare for a replacement. Therefore, battery level indicators work reliably only with alkaline batteries.