-Step in front of Radio Broadcasting Console at the Zenith Station in Altar.
-Press the DS4 Touchpad to go into Vicinity.
-Radio Console will not show in Vicinity.
-Place car or truck battery in hands
-While close to panel, the HUD will show the option to Attach to the panel using R2.
-After attaching the car or truck battery to the panel, it will no longer be available to retrieve either in vicinity or from the panel itself where applicable.

At least prior to the update, there have been issues with attaching two batteries to the panels at once. At various points, either only the car battery or only the truck battery could be attached and used with metal wire while the opposite type of battery was also directly attached. Which type of battery, car or truck, would be allowed to attach with wire would change arbitrarily, and sometimes it would seem to switch after a server restart.

Even if you could hook two batteries up at once, the panel would only use the power from one of the batteries. Once that battery was used up, the panel would stop working despite having a second fully charged battery attached as well.