September 2005- General Aviation aircraft standard instrumentation includes an ammeter or current load meter to monitor your electrical system. Electrical power is a combination of Volts x Amps = Watts, or power.
An ammeter tells you only half of the story. In addition, the indicator charging condition is typically only a needle width difference between charge and discharge conditions.
Visual Instruments manufactures an easy to read and install voltage monitor. If your 14-volt alternator fails, the bus voltage difference between charge—13.5 volts—and discharge—12 volts or less—jumps right out in your face with changes in color and position on the voltage monitor.
Operation
A 10-element light bar divided into 0.5-volt increments from 11.0 to 14.5 volts has three color-codes showing you the 12-volt electrical system’s condition immediately. Three green light bars from 13.5 to 14.5 volts are followed by four amber light bars from 11.5 to 13.0 volts, and finally three red light bars for 11.0 to 11.5 volts.
The 24-volt system monitor has similar light bar divisions. The Volt-age Monitor has an integrated dimming circuit for controlling light bar brightness under both day and night conditions.
Installation
The documentation includes installation instructions and electrical diagrams for suggested installations. The big question is where to attach the positive lead to the bus. Do you choose the primary bus or a secondary bus location?
Attaching to the same bus as a backup alternator installation makes sense. Find a spot on the instrument panel and decide whether to mount the monitor vertically or horizontally. Faceplates for both methods are included.
The only panel modifications required are one hole for the wires and two for the attach screws. Now get out your special tiny fingers to attach the two leads to the selected bus location and the installation is complete.
Total installation time including the Form 337 and logbook documentation is about an hour or so.
Conclusions
The Visual Instruments Voltage Monitor resides quietly on your panel, diagnosing your aircraft’s electrical systems health until needed, when the colors and changing light bar indications get your attention immediately. For less than $100 and an hour of A&P time, you will have a good electrical system diagnostic tool.
If you have a standby alternator on your aircraft, this instrument is vital for monitoring your electrical load. For those flying in instrument conditions, the Voltage Monitor merits your serious consideration.
Resources
Visual Instruments
4201 Riverside Drive
McMinnville, OR 97128
503 434-5038
visualinstruments.com
