That brings back memories! Yes, many devices before iPhone had normalized internal batteries indeed had aftermarket extended batteries. They would come with matching bulged back covers to fit the significantly oversized battery.
replyThat's true even today for HAM radio handhelds. There is a cottage industry of ever larger snap on batteries for Baofengs and others. Very handy.
replyRandom thought: Maybe Apple should use radioisotope batteries to never have to change them, ever. I jest.
My early iPhones had external battery cases, which even when attached (when travelling a long distance) were smaller than modern iPhones in the important dimensions.
replyThinkpad T480, with dual battery was a really great idea
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