Yeah, being real, a good butane soldering iron is amazing. But it can't be your primary if you're using an iron all day. They're for portability and quick jobs. Well, I guess if you keep a couple in rotation you could use them all day. It's the waiting to cool down and refill that makes them impractical for main bench use.

I used to have one that really was my only iron. But my use case was pretty much fifteen, twenty minutes of work on an RC truck, maybe some household use. Perfect job for a butane setup. It died though, the seals went kaput a few years ago.

But damn, I really did prefer it to electric. The lack of cord made it more agile, and it seemed to do a better job with delicate bits because it was hot. Didn't have to leave it in contact as long, which meant less spread of the heat.

I'd replace it in favor of my crappy old electric, but I just don't solder anything any more.

Like others said, this is not a great idea.

Unlike most battery powered devices, a spring iron in active use needs real wattage to operate, probably comparable to a small chainsaw or leaf blower. Those also just eat batteries.

The best recommendation is to just use a modern digital iron (see examples mentioned in other post by linker) with a normal ac adapter. Just bring a compatible battery bank, or make a cable for whatever brand of tool batteries you have (18-20V preferred). If you are into RC models of any kind (drones, cars, planes) and that's the reason you need it to be mobile, you have LiPos and you can just use those (xt60 onto a suitable cable).

The only downside is that there's still a cable between the soldering iron and the battery, but honestly it's fine, arguably even better as your iron isn't huge, heavy.

I use the Milwaukee M12 soldering iron a lot and it's great but a corded iron is always going to be better (unless your on top of a ladder).