A battery tether system for tethering a power tool battery is provided. The battery may include a tether receiver as an integral component of the battery or the battery may be retrofit with a sleeve or bumper including a tether receiver. The sleeve may include a clasp to overlay the retrofit battery and ensure that the tether receptacle remains coupled to the battery. The tether receiver may connect to the tool receiver and provide an electrical connection to the tool and a tether receiver for the battery. The battery system may include tether keys configured to be inserted into a slot and slide into a locking pocket of the sleeve or bumper.