With a 500 full cycle to 80% capacity, that two years if you drained it 100% to 0% every day and the battery still has 80% of its original capacity. To get to 5

With a 500 full cycle to 80% capacity, that two years if you drained it 100% to 0% every day and the battery still has 80% of its original capacity. To get to 50% capacity should be 5 years, again only if you ran your battery down empty every single day for 5 years. So lets have a complicated waterproof quick release battery case adding weight and volume to the phone so that its easy to replace once every 5 years...