No, the WL-20 / WL-20L's built-in battery is not user-replaceable.
Note: Charging issues may not always indicate a battery malfunction. Factors such as ambient temperature or prolonged disuse can also affect charging performance. If you are unable to charge the transmitter or receiver, or if the battery drains quickly after charging, reach out to us through Backstage (Roland Account required) or consult a local authorized dealer.
Caution: If you disassemble this product (except as instructed in the Owner's Manual) or modify it or any of its accessories, we cannot guarantee its performance afterwards. Additionally, we might not be able to provide repair services.