Could you point me at the file I would need to update in order to make a custom vehicle able to accept vehicle equipment?

For a list of equipment categories I have used (or just supported), you can look into prototypes/equipment-category.lua.
For what categories I have allowed on different tanks, you can look into prototypes/tanks.lua.

Adding "vehicle" to the grid will accept (most of) my vehicle equipment.

The question is about the same - how to add equipment from other mods to your tanks, in particular from Krastorio 2. I'm using AAI Programmable Vechicles mod. When a remote command is given to the tank to move, fuel disappears from the reactors and generators, but the batteries are working correctly. Krastorio 2 has equipment for remote charging equipment, but it cannot be installed in your tanks.

mekasha was asking about custom vehicles, not my vehicles of this mod.
You are asking about my vehicles.
On totally different aspects, so please raise another thread next time.

For the remote command part (of AAI?), it seems to be conditions checking in the script. If so, then it is not something I can interfere. Please report to where it is relevant to.

For support of Krastorio 2 (or any mod) equipment on my tanks, it can be done on either my side or Krastorio 2 side.
If you are asking me to do so, please send me the name of the related equipment category(s) to me.
Or you can ask Krastorio 2 to do so, as the name "remote charging equipment" seems suggesting it is kind of an universal equipment, which sounds would be working on every vehicle (not just on their vehicles and my tanks). Then it is more natural that Krastorio 2 should actually scan for all vehicles and add the related equipment category(s) to their grids.