Definition
A power supply circuit that converts a higher input voltage into a lower, regulated DC voltage suitable for powering electronic equipment that would otherwise require its own internal batteries. In aircraft electronics, a battery eliminator circuit allows avionics or accessories to draw their operating power directly from the aircraft electrical system instead of from dry-cell or rechargeable batteries.
Plain English
A small built-in power supply that lets a piece of equipment run off the aircraft's electrical system instead of needing its own batteries.
Context Anchor
Seen in aircraft electrical and avionics maintenance discussions, especially when portable or battery-powered equipment is operated from aircraft power or a bench power source.
Derivation
The name describes its function literally: a circuit that 'eliminates' the need for a battery by supplying the same voltage the battery would have provided. The term dates back to early radio equipment, when household receivers were redesigned to run from wall power instead of dry cells.
Why Pilots Care
Prevents unnecessary drain on the aircraft battery and keeps essential equipment operating reliably during flight.
Analogy
It is like using a plug-in adapter to run a small device from a wall outlet instead of putting batteries in it.
Intuition Check
Do not read “battery eliminator” as a circuit that drains, destroys, or disconnects a battery. Here it means a circuit that replaces the battery’s job by supplying power from another source.
Example Sentence 1
The handheld radio was wired to the aircraft through a battery eliminator circuit so the pilot would not have to swap batteries between flights.
Example Sentence 2
Before flight the pilot confirmed the battery eliminator circuit was active to avoid draining the standby battery.