I purchased a 15 inch MacBook Pro with retina display a couple months ago. Most of the time I use it with the ac power adapter. Is there any harm to the battery life if I never left the battery drain down some and then recharge it? I have come to understand that when the battery is fully charged and plugged in to an outlet the battery is basically on standby.
Thanks
If you use it mostly on AC, then once every one or two months you should use it on the battery until the battery runs down to about 20%. Then reconnect the AC so the battery can recharge.
About Batteries in Modern Apple Laptops
Extending the Life of Your Laptop Battery
Apple Portables- Calibrating your computer's battery for best performance
If you use it mostly on AC, then once every one or two months you should use it on the battery until the battery runs down to about 20%. Then reconnect the AC so the battery can recharge.
About Batteries in Modern Apple Laptops
Extending the Life of Your Laptop Battery
Apple Portables- Calibrating your computer's battery for best performance
It would be best if the battery got used occasionally to around 20%. Other than that, there is not much harm in leaving it plugged in, as long as it isn't hot all the time because heat really shortens battery life.
You are right that the battery isn't involved much when plugged in because the charging circuit automatically cuts off to prevent overcharge.
Using ac power adapter vs. battery on MacBook Pro
