Hello,
I have the Beaulieu 2008 Reflex Control model with the single contact in the center and the ground contact on the side.
It was supplied with a wire to connect it to a battery. I'm not sure where it's from, but it does say "Made in Germany", so I'm thinking it could be an old model from Chambless or Wittnauer. The other side of the wire has a 6-pin DIN connector with the center pin broken off. There are a red and yellow wire each soldered to a separate contact, and a green and blue wire soldered together to another contact.
I'm wanting to make a battery pack for this, either