External Battery Charger The Tektronix TDS3CHG is a External Battery Charger and an optional accessory for the Tektronix TDS3000B series digital phosphor oscilloscopes. The oscilloscope battery charges automatically when the oscilloscope is connected to line power. You can also charge the batterie with the optional external charger TDS3CHG. The Difference: Battery charging in oscilloscope with oscilloscope turned on or off: Typ. charging time 30 hours Battery charging with TDS3CHG external charger: Typ. charging time 5 hours For use with Tektronix TDS3000B series For use with the TDS3BAT/TDS3BATC battery packs (Li-Ion Akku-Pack TDS3BATC) Fast charger