A cordless cautery and cutting surgical device includes a modular battery and a surgical handle operable to removably hold the battery thereto. The handle has a cordless radio-frequency-signal-generation assembly and a surgical bipolar end effector having jaws and a cutting blade therebetween. The signal-generation assembly selectively supplies radio-frequency signal to the end effector when powered for electrocautery of tissue between the jaws. The handle defines therein an aseptically sealable battery-holding compartment selectively exposed to the environment and removably holding therein the battery. A motor assembly is disposed in the handle and is electrically connected to the battery and/or the signal-generation assembly and is powered and controlled thereby. The motor assembly physically couples to the blade and/or at least one jaw for moving the blade/jaw(s). The second connector part electrically connects the battery to the signal-generation assembly and/or the motor assembly when the battery is removably disposed in the compartment.