Use of Macbook pro (2019) in clamshell mode

I understand that in order to use a macbook pro in clamshell mode with an external monitor, power must be continuously supplied to the macbook. I have also been told that continually supplying power is detrimental to the battery life. Is there a dock, adapter or procedure available that allows clamshell mode with an external monitor but does not damage the battery life? And what is considered a normal battery life for said battery?

MacBook Pro (2017 – 2020)

Posted on Apr 17, 2023 7:53 AM

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Posted on Apr 17, 2023 10:24 AM

For more recent MacBook Pro models, this I much more nuanced.


Catalina software 10.15.5 and later for MacBook Pro with T2 chip (2018 models and later) includes a new feature called Battery Health Management. Based on your usage patterns, this widens the hysteresis to initiate a charge cycle at a lower level, and stop before 99 percent. 


About battery health management in Mac notebooks - Apple Support

About battery health management in Mac laptops - Apple Support


This relaxes the set points around re-charging (based on your usage patterns) and can improve long term battery lifetimes. When active, recharging may stop short of 100 percent charged. Recharging may only begin at a lower level (typically 80 percent level, variable based on usage patterns) than the previous "normal" threshold of 92 percent or less.


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Apr 17, 2023 10:24 AM in response to lauraleigh629

For more recent MacBook Pro models, this I much more nuanced.


Catalina software 10.15.5 and later for MacBook Pro with T2 chip (2018 models and later) includes a new feature called Battery Health Management. Based on your usage patterns, this widens the hysteresis to initiate a charge cycle at a lower level, and stop before 99 percent. 


About battery health management in Mac notebooks - Apple Support

About battery health management in Mac laptops - Apple Support


This relaxes the set points around re-charging (based on your usage patterns) and can improve long term battery lifetimes. When active, recharging may stop short of 100 percent charged. Recharging may only begin at a lower level (typically 80 percent level, variable based on usage patterns) than the previous "normal" threshold of 92 percent or less.


Apr 17, 2023 9:04 AM in response to lauraleigh629

<< I have also been told that continually supplying power is detrimental to the battery life. >>


That is a dangerous over-simplification.


Your MacBook Pro  uses ‘smart charging’ to charge in the optimum way, and only when necessary. Plugged in is Not necessarily actively charging. There is substantial hardware and software cooperating on battery and charging issues. Simply asserting a charging voltage against one of the interface(s) will NOT successfully charge your MacBook Pro.


In general, you should ALWAYS connect AC power when it is possible to do so, and only run on batteries (which could be somewhat slower) when no AC sources are at hand. Your Mac will NEVER over-charge. 


That computer is a battery-CAPABLE device. It is not optimized as a battery-operated device. (It is NOT an iPhone.)

Apr 17, 2023 9:59 AM in response to Grant Bennet-Alder

Thank you so very much for your reply. That clears up so much misinformation that we were given. I have been in IT for a long time but dealt primarily with PCs. Our organization is planning to migrate to Macs and this was a big concern. I had read about optimized charging with macs but could not find anything definitive (as clearly stated as you did above) to support my thought.

Use of Macbook pro (2019) in clamshell mode

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