: As batteries age, they lose capacity; for example, lithium-ion batteries often follow the 40–80 rule (maintaining charge between 40% and 80%) to delay this decay.

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: In vehicles, an aging battery puts excess wear on starting components like the starter motor.

: Many manufacturers offer pro-rata or full-replacement warranties. For instance, brands like Interstate Batteries define a "replacement battery" specifically as one purchased at an adjusted price based on previous warranty terms.