Flex® Annunciation Control Unit

Part of the Flex® product line, this digital Annunciation Control Unit (ACU) monitors and displays True Blue Power® Gen5 lithium-ion battery parameters. It features smooth, high-resolution graphics and provides status, state of charge, state of health, volts, amps, temperature, remaining life and fault data. View all Battery Accessories
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MD23-104 Flex Annunciation Control Unit thumb
MD23-104 Flex Annunciation Control Unit thumb


  • Standard 2-inch size
  • Lightweight — 0.4 lbs
  • Simple user interface — Push-and-turn control knob
  • Daylight readable LCD and high-definition graphics
  • External lighting control and built-in photocell for automatic dimming
  • Field-upgradeable software via standard USB-A port
  • Night Vision Imaging System (NVIS) compatible (available)
  • TSO-certified hardware and software (Design Assurance Level A)
  • Designed and built in Wichita, Kansas, USA
  • Two-year warranty


Model Number Flex MD23-104
Part Number 6420023-1
Data Input ARINC 429
Data Output ARINC 429
Battery Rechargeable coin cell (memory only)
Weight 0.4 lbs (0.17 kg)
Mounting Rear panel mounted, (4) #6–32 screws, 2.25-inch round bezel
Dimensions 2.43 x 2.43 x 1.0 inches
Mating Connector P/N 9019162-1: 26-pin, D-Sub electrical connector (Quick Disconnect)
Certification FAA/EASA TSO certified to C2d, C106, C113b
RTCA DO-160G qualified
RTCA DO-178C qualified, Design Assurance Level (DAL) A
Rights U.S. Patent 11,048,389


Installation Manual
IM 9019161

Technical Drawing
OL 6420023

User Guide


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True Blue Power® is a division of Mid-Continent Instrument Co., Inc. True Blue Power products can be purchased through Mid-Continent’s online shopping tool at

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