rcmmnds
Anker SOLIX C300 DC Power Bank Station, Outdoor 288Wh (90,000mAh), Portable Power Station, LiFePO4 Battery, 300W Solar Generator, for Camping, Traveling, and Emergencies (No Wall Charger Included)

Anker SOLIX C300 DC Power Bank Station, Outdoor 288Wh (90,000mAh), Portable Power Station, LiFePO4 Battery, 300W Solar Generator, for Camping, Traveling, and Emergencies (No Wall Charger Included)

also mentioned:

Anker Solix PS30 Solar Panel, 30W Foldable Portable Solar Charger, IP65 Water and Dust Resistance, Ultra-Fast Charging, Charges 2 Devices at Once, for Camping, Hiking, and Outdoor Activities.
Anker Power Bank Power Station 60,000mAh,Portable Outdoor Generator 87W with Smart Digital Display, Retractable Auto Lighting and SOS Mode, Home Backup(PowerCore Reserve 192Wh) for Travel, Camping

comments:

> if you're talking about the world being dark for 3 years, not sure batteries are the thing to stock up on friend

Friends don't let friends go camping with a bag full of replaceable phone batteries.*

A couple alternatives I like...

This costs considerably less per milliwatt-hour than even ~$20 replaceable phone batteries, and is rather more useful camping:

https://www.amazon.com/Anker-PowerCore-Portable-Retractable-...

If one needs more oomph, this is 6 lbs, so I wouldn't take it for a walk. Depends on the type of camping:

https://www.amazon.com/Anker-Portable-Generator-Traveling-Em...

For the little bank, something like Anker Solix PS30 Solar Panel charges like a wall wart with just a couple hours' midday sun in northern U.S. or southern E.U.:

https://www.amazon.com/Anker-Foldable-Resistance-Ultra-Fast-...

North of 40th, combo can get us through strings of rainy days off grid while not thinking about it.

To cost less, on Alibaba you can match case style, plug placements, and feature/functions to find the same OEM models as well-known portable power and solar brands for a fraction of price if one doesn't mind ship time.

* That said, this is all one's power eggs in one power basket. To your point, a bag full of batteries means one can fry half a dozen and still have a few juicy eggs to suck dry, but don't lose tools or phone bits and bobs on field replacements and one will still want a panel or two to top them off!