Definition
A metal bar used in aircraft battery installations to electrically connect two or more individual battery cells in series, joining the positive terminal of one cell to the negative terminal of the next.
Plain English
A short metal strip that links one battery cell to the next, so they all work together as a single battery.
Context Anchor
Seen in airframe maintenance and sheet-metal repair, especially when solid rivets are being installed.
Derivation
Each individual cell of a multi-cell battery was historically called a 'bottle' because early cells were housed in glass or hard rubber jars resembling bottles. The 'bar' is the metal connector that ties these bottles together.
Why Pilots Care
Proper use prevents valve damage and ensures reliable access to emergency oxygen or fire suppression systems.
Intuition Check
Do not read bottle bar as anything related to a fluid bottle or pressure. In aircraft maintenance, it is a metal riveting tool shaped like a bottle.
Example Sentence 1
During the battery inspection, the mechanic found a loose bottle bar between two cells and torqued it to the proper specification.
Example Sentence 2
Store the bottle bar with the oxygen equipment so it is always available for bottle changes.