MBP 2018 constantly in charger vs drain and then charge?

felixen

macrumors 6502a
Original poster
Apr 13, 2009
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I have my Macbook sitting on the office table where I use it daily. With my old MBA 2012 I had it plugged in the charger constantly because I always used it in that same spot anyway. However with my new MBP I want to take as good care of it as possible.

Do you guys recommend having the cable plugged in at all times, or is it better to drain the battery > do full charge > remove cable until battery drains > plug back in etc.?
 

_Kiki_

macrumors 6502a
Aug 13, 2017
841
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it's not an iPhone, it's a MacBook, you should use the same like every other MacBook, if you still don't know ask Apple
 

Eerriikkoo

macrumors member
Feb 6, 2017
77
34
I have my Macbook sitting on the office table where I use it daily. With my old MBA 2012 I had it plugged in the charger constantly because I always used it in that same spot anyway. However with my new MBP I want to take as good care of it as possible.

Do you guys recommend having the cable plugged in at all times, or is it better to drain the battery > do full charge > remove cable until battery drains > plug back in etc.?
You can keep it in the charger. Not neccessary to drain battery nowadays. Only when you are storing your macbook for a longer time Apple recommends doing that with a 50% discharged battery. Otherwise check this: https://www.quora.com/What-is-the-officially-best-way-to-keep-a-MacBooks-battery-healthy-and-long-lasting-Is-it-better-to-charge-to-full-and-unplug-it-or-charge-only-when-necessary and this:
https://www.apple.com/lae/batteries/maximizing-performance/
 
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Nbd1790

macrumors regular
Jan 2, 2017
179
83
New York
Don't think theres an issue if you keep it plugged in. I have a 2013 MBP that I use on a daily basis plugged into a home studio setup (always on charger because I used clamshell mode) My battery has been fine although a bit worn out because of its age, but my battery cycle count is around 450 and the status is considered to be "normal"
 
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Pangalactic

macrumors 6502
Nov 28, 2016
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605
Do you guys recommend having the cable plugged in at all times, or is it better to drain the battery > do full charge > remove cable until battery drains > plug back in etc.?
Don't drain it, it's a bad idea. For optimal usage discharging to 20% and charging to 80% is generally recommended. Which will give you just a little more battery life, so, for the most part, it's not worth bothering with.
 
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felixen

macrumors 6502a
Original poster
Apr 13, 2009
752
62
You can keep it in the charger. Not neccessary to drain battery nowadays. Only when you are storing your macbook for a longer time Apple recommends doing that with a 50% discharged battery. Otherwise check this: https://www.quora.com/What-is-the-officially-best-way-to-keep-a-MacBooks-battery-healthy-and-long-lasting-Is-it-better-to-charge-to-full-and-unplug-it-or-charge-only-when-necessary and this:
https://www.apple.com/lae/batteries/maximizing-performance/
Good info.

Thanks everyone! This sounds great
 

danbates

macrumors newbie
Nov 19, 2018
7
0
Wales, UK
Yep, just to second that, keeping it plugged in is fine.
Personally, I know how much energy the adaptor takes not even connected to the laptop, so I choose to disconnect it / unplug it for environmental reasons, and just close the laptop lid for standby mode.
Storing in a discharged state I think is still debated, whether it's for safety or longevity isn't clear I find. My intitalresearch shows that Li-ion has longevity in a fully charged state, and any amount of discharge shortens it's life. Of course, it's a huge industry, so if the manufacturers say store it in a state of discharge, it's clearly in their benefit, as it's more likely to shorten the battery life.
The storage stage of charge thing is to do with the battery dialetric, and that technology is changing so fast.
 

zhenya

macrumors 603
Jan 6, 2005
6,357
2,822
Keeping it fully charged on the power brick is not ideal and over the long term it will have an adverse effect on your battery. I’m certain you’ll have a long list of people debating this point, but this is simply how battery chemistry works. Some manufacturers like Lenovo have software built-in that allows you to configure this, say by limiting charge to 95%, and not charging the battery at all until it drops below say 60%. Doing this greatly increases the life of the battery, but comes at the expense of some inconvenience - your laptop may have been on the charger all day, you take it off to use it, but the battery is still at 61% because it hadn’t dropped below the ‘start charging’ threshold.

This is why Apple doesn’t include this kind of software. Charging the battery normally whenever it is plugged in is expected behavior and more convenient, even if it has some detrimental effect on the overall battery life. The reality is that replacing the battery is not overly expensive as proportion of the overall cost of the machine over its total lifespan. So I’d use it without worry and replace it if you ever need to.
 
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danbates

macrumors newbie
Nov 19, 2018
7
0
Wales, UK
That is interesting, thanks.
It would be useful if there was a mac app to control battery charging more, to take over from the SMC.. I found fruit juice, but the cost itsn't justified when, like you say, it's cheap to replace the battery (and easy). I guess if you're paying for a technician to do it, then the cost of an app like fruit juice may be worth while.

I've read the full charge state / longevity issue in not to do with the fundamental chemistry, but the dialetric choice, and the way it can potentially breakdown from consistently full charge and begin leaking charge more rapidly. There are dialectris which do not suffer this problem, perhaps we'll see them in the market some day.

If you read this article, you will see that the main factor is not the 'peak charge voltage' but instead, the number of cycles.
https://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries
Importantly though, the 'peak charge voltage' does play an important role like you say.
Instead of 4.2V/cell the optimum is stated as 3.92V/cell, 'Battery experts believe that this threshold eliminates all voltage-related stresses'. How does this translate to percentage? On my mbp, late 2011 with 10.95V pack, I estimate it's about 75-80%, based on looking at my system information now.. I'll check this again out of interest.

Further down in the same article, What can the user do?
"A laptop battery could be prolonged by lowering the charge voltage when connected to the AC grid. To make this feature user-friendly, a device should feature a “Long Life” mode that keeps the battery at 4.05V/cell and offers a SoC of about 80 percent. One hour before traveling, the user requests the “Full Capacity” mode to bring the charge to 4.20V/cell."