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I purchased Mac book air 13.3" in June 2015 and rarely used. It was not powered up for 4 months. Now when I switched it on battery is dead but machine powers up with charger not charging battery at all and shows replace battery now. Battery has done only 25 charging cycles
Lithium Ion batteries are like muscles. They need to be exercised. Frequent Charge/Discharges prolong the battery’s life. Put it in storage, and batteries can and have gone bad. The battery is replaceable. Follow this guide on a battery replacement. MacBook Pro 13" Retina Display Early 2015 Battery Replacement
