Save battery life with low-powered adapter ?

[lu31]

Hello,

A friend of mine told me he uses an under-powered adapter on his 15 MPB just to charge it slowly in order to save its battery life (a slowly charging battery is theoretically supposed to "better" charge, resulting in less degradation over charging cycles) For example using 61W or 30W instead of 96W.
Did any of you ever heard of that method to preserve the battery ?
What do you think of it ?

thanks in advance

 

[Patcell]

You could certainly do that to charge the battery when not using the machine, but the lower output power adapters won't supply enough energy to run the laptop at nearly full capacity. In other words, if you are using the computer for anything remotely intensive, it is likely the battery would lose power when connected to the 61-watt power adapter (let alone the 30-watt adapter).

I have used my 15-inch Pro with a 61-watt power adapter to charge the battery while doing light stuff (web browsing, word processing, etc) and it worked just fine. I once accidentally used the 61-watt adapter while the 15 inch was connected to two external 4K monitors working on photo edits and the battery drained.

 

[magbarn]

With light use and not activating the amd gpu with either apps or external display you can easily power the mbp 15/16 with even a 45 watt power adapter. Once you activate the dgpu all bets are off. Theoretically a lower watt charger can prolong battery life due to slower charging but keeping a battery between 20-80% charge would prolong much further than a faster charge.

 

[lu31]

Thank you for your replies !
Meanwhile I bought an apple 30W adapter (the one for the 12 inch Mac book I guess). It works as I expected it would, I mainly do webbrowsing, video conference, libreoffice, remote connection for remote programming (so no intense CPU or GPU task) and event with many desktops and browser tab open, while plugged, the 30W adapter manage to charge the battery, quite slowly, so the number of charge/discharge cycles between 20% and 80% is reduced.

 

[jaytv111]

Main thing with battery longevity is heat, if you charge in a hot environment then I would go for a lower power adapter (but you probably shouldn't charge in a hot environment if you can avoid it). Other than that the Macbook Pro has no problem keeping cool if ambient air is cool too. So I doubt it makes a difference for regular use, the battery will receive the same charge with the regular one or a lower power one, it'll just be a bit slower.

You often see this with phones that they will fast charge and they will heat up a lot during fast charge (depending on how fast they will go), and that heat can be a horrible thing for the battery. In the Macbook Pro's case it doesn't generate extreme heat from charging with the normal power adapter, but if you were using full CPU and GPU and charging at the same time the whole system in general would generate heat but as long as it can cool with its fans it's supposed to be fine.