If you don't just wander about in Power Armour and use it purposefully, there are plenty.
I am Power Armor/BoS DWEEB and can tell you with the Nuclear Physassist perk you can wander in it. In fact I DOUBLE use cores as I am constantly in PA and use a Gatling Laser as my main weapon of death and zero issues. Certain vendors always restock with cores. They can be expensive though.
I'll send you mine.
I don't even use power-armor and I have 9 of them and I'm only level 14. I really need to stop exploring EVERYWHERE and actually do some of the quests.
Fantastic idea.
How many water purifiers do you have running?
Also, to OP, I agree with others, no way to recharge. There was a rumor going around early on that you could recharge them somehow at a "generator". Turns out this was some kind of viral falsehood.
cores are so easy to find, if you look everywhere. and i mean EVERYWHERE. i find them in all kinds of containers. Last night, i found on in a garbage can outside. I roam in my PA. The only time i get out is when im at my house. I have yet to use up a core before finding at least one (if not two or three) to replace it. currently have 17, and have never ran out or bought one. There is a limited supply of them out in the wasteland, but vendors never run out. So far the cheapest ones i have seen are sold by the BoS vendor. Going for about 506 caps a pop. But like i said, i neve3 buy them. I do however, look in just about every corner and every container i can find. I love the new "everything has a use" system. Love just going exploring and picking up everything i can find.
I tried to stick one back into the generators they come out of but you can't. I also tried making a bottled water factory. 194 water at the settlement but they dont stockpile purified water in my workbench. Maybe i need more scavengers at that location. I still havn't started using PA in earnest but do plan to. Not much else to buy but cores and ammo. All the best guns in the wasteland are free. With 2 barter perks I can buy cores for under 500. Something like 426 from the guy in goodneighbor who seems more than happy to sell them to me.
If you aren't above being a bit mercenary, you can loot lots of Fusion Cores off BOS Knights. I've found up to 8 Fusion Cores on a single BOS soldier. Of course, that is if you didn't take the very fun route of shooting their fusion core and turning their power armor into a little nuclear bomb.
Don't let them run down to zero charge either. Vendors will pay top dollar for a core with any charge left in them. So you will get the same amount of caps for cores charged 100/100 as you would with ones with 1/100.
I saw that idea too.
All of my settlement have loads of water pumps. Even the ones without access to a river or the sea have multiple small water pumps.
Keep in mind, they're considered ammo. So they'll appear where ammo can appear and are likely affected by the Scrounger perk. I have a couple points in that perk and can find 4 or 5 fusion cores at a time.
Ah, that is good to know, I was finding it frustrating that if I don't manually pop a used fusion core in a suit before hopping in it default inserts a fresh one. I was getting annoyed at having several half full cores in my inventory. I think The game defaults to a fresh one if you are in the suit and the core runs dry also, so it would be easy to just hop out and swap cores when they run low to save em and sell them latter. You can pretend that the merchants know how to refill them.
Level 49 and I'm up to 79 cores. Just picked up the Nuclear Physicist perk so it's like I have even more than that.