Earlier quoted context omitted.
> I'd much rather be able to swap a charged battery for the drained one in my phone especially in circumstances when I'm in a foreign country and dependent on my phone I don’t deny that this is a valid use case for you, but I’ve absolutely never been in this position. I carry around a battery phone charger in situations where I’d depend on my phone. If you squint, yes that’s pretty similar, but the big difference is…
Carrying around bulky power banks or worse, chargers to then tie you to sit close to an outlet and wait for the battery to charge, is not entirely ideal when you're on the go, foreign or domestic. It's also less anxiety-inducing to not have to worry about where will I get my next charge and how long will it interrupt my plans for.
For mm^3/Wh, the results are:
Small vendor swag power bank: 96 x 21 x 26
52_416 / 7.4
7,083 Canon battery: 42 x 30 x 9
11_340 / 4.5
2,520 10,000mAh dual USB power bank: 139 x 22 x 60
183_480 / 37_000
~5 By volume / energy, the big power bank wins by a mile. And tbh its not that huge, similar footprint to my phone and about twice as thick. Plus, it can power two devices at once, which can be pretty handy. It has a bit over twice as much power as my phone's battery. This logically makes some sense, as phones these days are pretty much a battery and a screen with a small logic board tagging along for the ride.
If I'm on the go, I'd much rather have a large battery bank that provides a good bit of flexibility rather than a battery that only works with a single device. This one battery pack can charge my phone, my camera, my wireless mouse, my keyboard, my headphones, my e-reader, and then all the same list of stuff for my spouse. If I got a fancier one, it could even provide extra juice to my laptop. If I only had a battery specifically made for my phone, I'd only be able to swap out my phone battery and all of the rest of my devices would need their own batteries or just be left dead.
On top of that, if I wanted to then charge that battery outside of the phone I'd have to lug some specific charger for that model of battery. Meanwhile if I bothered getting a newer USB-C power pack the same power cable that charges my laptop and my phone and my headphones can also recharge my spare battery along with all the rest of the devices I mentioned. I'm much happier having a 10,000mAh battery pack in my backpack to recharge when needed than needing to think about having a few different batteries around and their related chargers to keep track of. Once this one dies I'll probably