Abstract: Battery powered, keyless locking container cap configured securing a bayonet filler neck or threaded filler neck remaining unlocked after attachment. A timer circuit powers off placing the invention into an energy saving, mode; a compression spring forces a coupler into engagement. While engaged, the cap can be removed and replaced. Cap rotation by an unauthorized user, locks the cap. A backup, rotary pin coded lock is in the interior inaccessible. Cap rotation enters a pin code to unlock or lock the cap. The invention supplied is with a transmitter configured as a key fob or a cigarette lighter power plug. the transmitter signals the cap not to lock thereby providing removal. rotational Comprising rotary frictional slippage prevents unauthorized removal by limiting both speed and the rotational force to a level insufficient to override the attachment torque.