The Charging Bay Indicators where developed by Michael Erwin.
The CBI (+ DPL) are similar to Teeces. They run of a Arduino breakoutboard.
The best one would be the Arduino Pro Mini Breakoutboard.
Bevause it has a second input for voltage measurement that is displayed via the 3 LEDs on Led 21-23.
The are many sketches for this, but i found only one to be good enough to run both Displays (CBI & DPL) in a good way.
These boards only take 5V!