In researching the related question How can I break items down into their components, I saw a complaint on Reddit to the effect that the extra, leftover materials get destroyed.
Why this is a common belief
Many people seem to believe this, and there's a good reason for that: it's confusing. And it's confusing for two reasons:
- The composite item is removed from your character's inventory, but the leftover components are placed in the Workshop's inventory.
- There's sometimes a delay before the leftover components reappear. If you want to speed up the process: go into Workshop mode, try to build something, and then exit. This appears to force the Workshop to update its inventory contents list.
Go, science!
I settled the question with science. I've tested this with various items a dozen or so times using the Armor Workbench, the Weapons Workbench, and the Workshop crafting menu.
The leftover components have always (so far) appeared in the Workshop inventory, but there's sometimes a delay.
Here's one of the experiments:
Experiment
- Remove all Lead from your inventory and the Workshop's inventory.
- Add two pencils to your inventory; each pencil has 1 Lead and 1 Wood.
- Go into the Wood Structure crafting menu—not to craft anything but just to check your Wood component count.
- Craft a Radiation Emitter, which among other things requires 2 Lead.
By creating the Emitter, we force the Workbench to dismantle the pencils, which liberates 2 Wood and 2 Lead.
If our Wood component count goes down, wood has been lost/destroyed. If it stays the same, our 2 "potential" units of Wood have simply been converted into 2 actual units of Wood.
Result
Our Wood component count remains unchanged. So unneeded materials are retained, just as though you'd broken the item down yourself.
After some experimentation, and expanding on information in the comments:
Short answer
- Because of bug.
- But it doesn't really matter.
Long answer
[The problem]
This happens consistently in my Sanctuary settlement too, the only settlement where I have spotlights installed. I have two spotlight turrets; each is on level ground, and each is right next to its own dedicated generator.
The problem appears to be triggered by the passage of time rather than fast travel itself. For example, a very short fast travel (e.g., to Vault 111 and back) leaves the spotlights on, but a little further (e.g., to Starlight Drive In and back) and they'll turn off.
But most importantly, the problem is only cosmetic.
[The experiment]
Wait until a spotlight turret is in its darkened state, then:
- Note that it's still moving; this strongly suggests that the game still considers it to be active.
- Go into Workshop mode and notice your settlement's defense number.
- Pick the turret up and set it back down. It should be lit now.
- Notice your settlement's defense number is the same whether or not the turret is lit, so long as it's moving.
Then, to be extra sure:
- Fast travel a good distance, for example, from Sanctuary to Starlight Drive In.
- Return to your base. The spotlight should be dark.
- Check your settlement's defense number. It's the same.
[So...]
While a little lighting in your settlement would be convenient—not to mention darned pretty—this appears to be a purely cosmetic bug.
You can sleep soundly knowing that those turrets, even when dark, are scaring away bad guys. And you can also sleep soundly because those turrets won't keep shining in your window. (Until Bethesda fixes this bug.)
Best Answer
You need to ensure that both sets of lights are on separate circuits.
So, for example, have all your normal lights connected to on set of generators in the settlement, then create a separate detached generator, and connect the terminal and light boxes to that generator.