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mikebjammin

macrumors newbie
Original poster
May 23, 2020
29
5
Title. I got my 16 inch MBP this week and it has been great so far. 90% of the time I work at my desk with my MBP plugged into an external monitor and unplug the computer when I put it into "Sleep" mode. Is leaving it plugged in even when it is fully charged bad on the battery? I have always heard mixed things. I appreciate any replies!
 

||\||

Suspended
Nov 21, 2019
419
688
No, it's not. My two year old 13" is plugged in most of the time and is still at 94% capacity. 30-something cycles.
 
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benjai

macrumors member
Oct 1, 2009
87
20
It’s not as bad as it used to be. If you run it off the battery once a week or so it should be fine.

Sorry, why is this necessary? My 13" is almost always in clamshell and always plugged in. Is this bad?
 

jbachandouris

macrumors 603
Aug 18, 2009
5,766
2,891
Upstate NY
Sorry, why is this necessary? My 13" is almost always in clamshell and always plugged in. Is this bad?

It's necessary as running any laptop plugged in all the time is bad for battery life. As the previous poster said, it's not as bad as it used to be as battery tech has advanced, but it's still not a good practice.
 

Superhai

macrumors 6502a
Apr 21, 2010
711
521
Is leaving it plugged in even when it is fully charged bad on the battery? I have always heard mixed things. I appreciate any replies!
It is a bit complicated.

The short answer is yes, it is bad for the battery.

The longer answer is that you have to look at your use pattern, typically with current chargers they don't keep the battery charged at 100% constantly, but let it discharge slightly, in that way the batteries the discharge cycles will extend to around 1000. So now if you do a full discharge once a week it means you will be able to use the battery for close to 20 years if you ignore other factors. So does it really matter?

The longest answer is that Li-polymer batteries have the longest longevity at around 3.9V, which is typically 60% of "full capacity", so if you keep it at that level constantly you can expect up to maybe 5000 discharge cycles. Some devices where it is more important to avoid changing the battery often instead of longer use on single charge, will rather keep full charge at "60%" rather than the typical 4,2V common laptop and cell phones do. That is why long time storage also is kept at around 50-60%.

High and low temps will kill your battery earlier than discharge cycles these days, just run a full discharge at least occasionally (once a month is a good number). If you keep it at a chill room temperature and use original modern charger, I am sure you will end of life the laptop itself before the battery. It will lose capacity, but by a little care and if it is not defective it should last a long time if you keep it connected.

Heavy usage where the laptop battery becomes warm often, that will on the other hand shorten the lifetime quickly, if you discharge it every day, and need to charge it to max, then expect max just a few years before you need to change it.
 

Juicy Box

macrumors 604
Sep 23, 2014
7,495
8,803
For older Macs, they should not be plugged in all the time. Apple recommended to occasionally drain the battery because according to them it is "important to keep the electrons in it moving occasionally".

Sorry, why is this necessary? My 13" is almost always in clamshell and always plugged in. Is this bad?
It depends on the Mac and OS versions.

In Catalina, there are options to optimizing battery life for cases like yours, but IIRC, they are not the default, and must be turned on in System Preference.

For older Macs and older versions of MacOS, there wasn't anything to address charging levels for long-term clamshell use. There are a 1000 articles on the internet explaining why this is a bad thing, and Apple used to have this on their support website, but I can only find it archived now:

 
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mikebjammin

macrumors newbie
Original poster
May 23, 2020
29
5
For older Macs, they should not be plugged in all the time. Apple recommended to occasionally drain the battery because according to them it is "important to keep the electrons in it moving occasionally".


It depends on the Mac and OS versions.

In Catalina, there are options to optimizing battery life for cases like yours, but IIRC, they are not the default, and must be turned on in System Preference.

For older Macs and older versions of MacOS, there wasn't anything to address charging levels for long-term clamshell use. There are a 1000 articles on the internet explaining why this is a bad thing, and Apple used to have this on their support website, but I can only find it archived now:


How do I change that center in Catalina? Do I unclick "Battery health management" or something else?
 

jerryk

macrumors 604
Nov 3, 2011
7,415
4,204
SF Bay Area
How do I change that center in Catalina? Do I unclick "Battery health management" or something else?
Yes.

But not sure why you want to uncheck it if you are at all concerned about battery life. The software is going to be able to do it better than any of us can manually. Maybe if you had to use it on a plane. But, even then there is power at the seats of most aircraft.
 

Juicy Box

macrumors 604
Sep 23, 2014
7,495
8,803
I forgot to mention my story when I had an iBook G3 battery go completely dead due to leaving it plugged in. I know that battery technology has changed over the last two decades, but the truth is that Apple has only recently addressed optimizing battery life for their laptop batteries.

About the iBook, I didn't deliberately leaved it plugged in, but when I was in the military, I was supposed to be deployed to Afghanistan for only 7 weeks, and worried that my iBook would become dirty, damaged, or lost, I sent it to my parents to keep for me until I got back.

I told them that they could use it if they wanted, as their computer was much slower.

The 7 week deployment turned into a 7 month deployment.

When I finally got back stateside, I visited my parents and to get some of my stuff. I unplugged my laptop and it just went blank. The battery was totally, completely dead, and wouldn't hold a charge anymore.

My parents had it plugged in sitting on their computer desk since I sent it to them.

Again, I get that my iBook's battery is different than today's batteries, but the problems still remained with the laptop batteries until only recently with Catalina.
 

Supra Mac

macrumors 6502
Jan 5, 2012
283
119
Texas
I use Al Dente and set it to 75%.

From site.
Why do I need this?
Li-ion and polymer batteries (like the one in your MacBook) last the longest when operating between 30 and 80 percent. Keeping your battery at 100% at all times can shorten the lifespan of your notebook significantly. More information can be found here: https://batteryuniversity.com/learn/article/how_to_charge_when_to_charge_table

How does it work?
The tool writes the desired value to your MacBooks SMC (System Management Controller), which handles the rest. For everyone that is curious, the modified SMC key is called "BCLM" (Presumably "Battery Charge Level Max")
 

alexfc

macrumors member
Jul 13, 2012
62
35
It is a bit complicated.

The short answer is yes, it is bad for the battery.

The longer answer is that you have to look at your use pattern, typically with current chargers they don't keep the battery charged at 100% constantly, but let it discharge slightly, in that way the batteries the discharge cycles will extend to around 1000. So now if you do a full discharge once a week it means you will be able to use the battery for close to 20 years if you ignore other factors. So does it really matter?

The longest answer is that Li-polymer batteries have the longest longevity at around 3.9V, which is typically 60% of "full capacity", so if you keep it at that level constantly you can expect up to maybe 5000 discharge cycles. Some devices where it is more important to avoid changing the battery often instead of longer use on single charge, will rather keep full charge at "60%" rather than the typical 4,2V common laptop and cell phones do. That is why long time storage also is kept at around 50-60%.

High and low temps will kill your battery earlier than discharge cycles these days, just run a full discharge at least occasionally (once a month is a good number). If you keep it at a chill room temperature and use original modern charger, I am sure you will end of life the laptop itself before the battery. It will lose capacity, but by a little care and if it is not defective it should last a long time if you keep it connected.

Heavy usage where the laptop battery becomes warm often, that will on the other hand shorten the lifetime quickly, if you discharge it every day, and need to charge it to max, then expect max just a few years before you need to change it.

From what I’ve read, fully discharging the battery doesn’t help. It’s best to keep it around 75-65%.

86F6A87E-7B5A-45C2-B9BF-712A0B75A761.jpeg


“Similar to a mechanical device that wears out faster with heavy use, the depth of discharge (DoD) determines the cycle count of the battery. The smaller the discharge (low DoD), the longer the battery will last. If at all possible, avoid full discharges and charge the battery more often between uses. Partial discharge on Li-ion is fine. There is no memory and the battery does not need periodic full discharge cycles to prolong life. The exception may be a periodic calibration of the fuel gauge on a smart battery or intelligent device. (See BU-603: How to Calibrate a “Smart” Battery)”



What Can the User Do?
Environmental conditions, not cycling alone, govern the longevity of lithium-ion batteries. The worst situation is keeping a fully charged battery at elevated temperatures. Battery packs do not die suddenly, but the runtime gradually shortens as the capacity fades.

Lower charge voltages prolong battery life and electric vehicles and satellites take advantage of this. Similar provisions could also be made for consumer devices, but these are seldom offered; planned obsolescence takes care of this.

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.

The question is asked, “Should I disconnect my laptop from the power grid when not in use?” Under normal circumstances this should not be necessary because charging stops when the Li-ion battery is full. A topping charge is only applied when the battery voltage drops to a certain level. Most users do not remove the AC power, and this practice is safe.

Modern laptops run cooler than older models and reported fires are fewer. Always keep the airflow unobstructed when running electric devices with air-cooling on a bed or pillow. A cool laptop extends battery life and safeguards the internal components. Energy Cells, which most consumer products have, should be charged at 1C or less. Avoid so-called ultra-fast chargers that claim to fully charge Li-ion in less than one hour.


Source: https://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries
 
Last edited:

alexfc

macrumors member
Jul 13, 2012
62
35
I use Al Dente and set it to 75%.

From site.
Why do I need this?
Li-ion and polymer batteries (like the one in your MacBook) last the longest when operating between 30 and 80 percent. Keeping your battery at 100% at all times can shorten the lifespan of your notebook significantly. More information can be found here: https://batteryuniversity.com/learn/article/how_to_charge_when_to_charge_table

How does it work?
The tool writes the desired value to your MacBooks SMC (System Management Controller), which handles the rest. For everyone that is curious, the modified SMC key is called "BCLM" (Presumably "Battery Charge Level Max")

Is it better to use Al Dente instead of the Mac battery health management?
 

Supra Mac

macrumors 6502
Jan 5, 2012
283
119
Texas
Is it better to use Al Dente instead of the Mac battery health management?

Yes, the whole battery health management is a bigger benefit to Apple and not the end user. Extends battery just enough to reduce battery warranty claims while not moving the needle much on extending battery life long term. To do that you need something like Al Dente and set the max level to 60%-80% and switch manually higher if you please when needed.

When I had it enable (Apple feature) it just went from 100-90-100% once a day, just adding cycles at the extreme end of charge. My work laptop HP Elite "something or other" keeps my battery 75-80% with the Bios enable feature to extend battery life. So looks like other manufactures provide this to benefit the end user.
 
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Supra Mac

macrumors 6502
Jan 5, 2012
283
119
Texas
Also to add on Al Dente, you can close the program and it will still remember the desired charge level, you don't need to have a plate of spaghetti in your menu bar. I think it resets though if you reboot.
 

Superhai

macrumors 6502a
Apr 21, 2010
711
521
From what I’ve read, fully discharging the battery doesn’t help. It’s best to keep it around 75-65%.
As it says in the text you have added as well, you need to do it occasionally to recalibrate the smart battery controller, if not you may not know what is the correct current charge level. Although if you never care about the battery meter in the OS, you probably could just use a voltmeter to ensure it remains around the ideal voltage. But that may be more awkward compared to just do a complete discharge.
 

ParagJain

macrumors 6502a
Jul 24, 2011
587
140
strictly my opinion as I am no expert on this ..

if you are able to maintain a good usage pattern (suitable to your case), you really don't need to install anything or worry about anything, it will serve you good.

I have a MBP 2015 model - as per istats commandline output -

--- Battery Stats ---

Battery health: unknown
Cycle count: 472 ▁▂▃▅▆▇ 47.2%
Max cycles: 1000
Current charge: 1726 mAh ▁▂▃▅▆▇ 32%
Maximum charge: 5485 mAh ▁▂▃▅▆▇ 83.6%
Design capacity: 6559 mAh
Battery temp: 24.59°C

I have 83.6% with 472 usage cycles.

Before 2020 Covid-19, My usage pattern was : Charge overnight, use most part of day at office on battery, charge occasionally.

On-going 2020 Covid-19, I am technically using MBP as a desktop connected to monitor most of the days. I simply turn off the main power after sleeping it in the evening and turn on the power next day, battery falls about 20-25% thru the night and the cycle continues.

the stats above look good for me to continue using it for another year, 6 years of usage on the hardware, i think its a solid return on the investment; Will give this to kids next year and buy a new one and i hope, i will be good for another 5-6 years.

no battery management software is installed, just good usage patterns has helped the longevity of my investment.
 
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