Many players enjoy the idea of leaving their armor wherever they’d like. It would be a disaster for someone to steal it, though. Can I leave my Power Armor in Diamond City?
You can leave your Power Armor in Diamond City after removing the Fusion Core. Without the core inside, NPCs won’t be able to steal it.
Fusion Cores are incredibly rare items that Diamond City citizens don’t carry. The Power Armor will safely stay in the location you’ve left it until your return.
If you can leave your Power Armor in Diamond City
Players are able to store their Power Armor at designated stations. Still, many players like the idea of leaving their armor wherever they want. The only issue is that NPCs van accidentally transport your armor all across the map.
A suit of Power Armor can only be activated by inserting a Fusion Core. A rare item, each core offers about 20 minutes of real life time (without sprinting) for the player to wear the suit.
If the player removes their Fusion Core from their suit, then the suit is pretty much safe. Although it is true that an NPC could theoretically possess a Fusion Core and steal your suit, this is incredibly unlikely.
Around 5 hours into the game, we removed a Fusion Core and left our suit at a local shop in Goodneighbor. Not interested in using the suit, we wanted to leave it in a spot that provides quick fast travel access.
After about 20 more hours of gameplay, the suit still remains in the same exact spot. Without the Fusion Core inside, no normal NPC in the area had the ability to hijack it.
This gives reason to believe that something similar can be accomplished in Diamond City.
So that’s the answer. You can leave your Power Armor in Diamond City after removing the Fusion Core. Without it, random NPCs won’t be able to hop in your armor and run away.