If you blow on this balloon, it'll inflate. If you inflate it a lot and then let it deflate it has all of these stretch marks. Those stretch marks are now a per

If you blow on this balloon, it'll inflate. If you inflate it a lot and then let it deflate it has all of these stretch marks. Those stretch marks are now a permanent defect. The same happens with your battery. If you charge it to 100% a lot and leave it there then it gets "stretch marks" and the permanent defects affect how long the battery lasts.