Use for a generator?

Hi guys,

For my own education, I would like to ask what do you use the generator for that I see is included in several slide-in TMs? Does the generator produce enough juice to run external equipment such as a vacuum, lights, or ??? or is it just used for internal use for the electronics on the slide-in?

Just trying to learn something here so let me know if my question doesnt make sense. Thanks in advance.