What should I limit my battery charge level to?

[yukari]

Note that when using charge limiter, your recorded number of cycles will increase every time you reach your set maximum... So you may end up with a HIGHER cycle count using Charge Limiter.

Are you sure about this? I haven't tested it out myself. I've read this but this seems kind of strange if it behaved this way.
...

I don't think this is correct. I have been using my charge limiter for over a month and the number of charge cycle does not increase every time it reaches 55% I set on my MBP when plugged in. I don't know how the electronic system is set up for counting the charge cycle, but my guess is it is related to amount of battery drain and full charge.

For example, if it is plugged in all the time, one charge cycle will be when the battery has drained "enough times" to make up 100% (or some arbitrary value like 80% or 90%). So if it is plugged in all the time, it may take a month for the charge count to go up by 1 (as the battery always drains slowly even when plugged in) when the amount of discharge "counted" by the electronic system equals 100% (or some other value).

 

[teidon]

I've had it for 5 months and it's already at 93% battery capacity with 70 battery cycles. Whether the drop is from sitting at 100% charge, or the heat, or a mix of both, I don't know.

It is both of them. Battery University says in their article BU-808: How to Prolong Lithium-based Batteries following:

Lithium-ion suffers from stress when exposed to heat, so does keeping a cell at a high charge voltage. A battery dwelling above 30°C (86°F) is considered elevated temperature and for most Li-ion a voltage above 4.10V/cell is deemed as high voltage. Exposing the battery to high temperature and dwelling in a full state-of-charge for an extended time can be more stressful than cycling.

In terms of longevity, the optimal charge voltage is 3.92V/cell. Battery experts believe that this threshold eliminates all voltage-related stresses; going lower may not gain further benefits but induce other symptoms.

They also have this table with maximum charge levels and how many cycles the battery lasts with each of them (they don't specify if the battery's capacity ends up being 70% or 80% after the cycles):

Charge level (V/cell)	Discharge cycles	Available stored energy
4.20	300–500	100%
4.15	400–700	90–95%
4.10	600–1,000	85–90%
4.05	850–1,500	80–85%
4.00	1,200–2,000	70–75%
3.90	2,400–4,000	60–65%

Based on these I would say that if you are going to use the laptop plugged in, setting the maximum charge level to about 60% would be best. If you instead use it on battery, maximum charge level should be kept below 85%. Also the battery shouldn't go below 30% charge level if you want to maximise its lifetime.

 

[iRun26.2]

It is both of them. Battery University says in their article BU-808: How to Prolong Lithium-based Batteries following:





They also have this table with maximum charge levels and how many cycles the battery lasts with each of them (they don't specify if the battery's capacity ends up being 70% or 80% after the cycles):

Charge level (V/cell)	Discharge cycles	Available stored energy
4.20	300–500	100%
4.15	400–700	90–95%
4.10	600–1,000	85–90%
4.05	850–1,500	80–85%
4.00	1,200–2,000	70–75%
3.90	2,400–4,000	60–65%

Based on these I would say that if you are going to use the laptop plugged in, setting the maximum charge level to about 60% would be best. If you instead use it on battery, maximum charge level should be kept below 85%. Also the battery shouldn't go below 30% charge level if you want to maximise its lifetime.

This is discouraging. I don't want to have to pay that much attention to my battery charing levels or when it is at full charge. It it is really so important why doesn't Apple manage the battery's charge for us?

Edit: Never mind, I see that the app takes care of it automatically. It still seems like Apple should have built in software that does this for us.

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Apple gives an estimate for the number of cycles, but your own use of the battery determines the actual number of cycles your battery will have. The reason they cite a 50% charge level as good is this puts the least strain on the battery by having half the lithium ions in the lithium cobalt oxide layer and the other half in the graphite layer.

Practically, keeping a 50% charge is really difficult, so often people recommend a range of 20-80% charge. The further you go in either extreme, the more stress on the battery and the fewer cycles it will have before degrading; all other things being equal.

I have always thought (because I think I heard it somewhere) that you should run your computer's battery all the way down once in a while. I guess that's not the case (as, now that I think about it, I should know since I have an electric car! I know they should not be run down to a low value). ?

 

[yukari]

I have always thought (because I think I heard it somewhere) that you should run your computer's battery all the way down once in a while. I guess that's not the case (as, now that I think about it, I should know since I have an electric car! I know they should not be run down to a low value). ?

That is for metal-hydride batteries, which are predecessors to Li-Ion batteries currently being used in laptops.

 

[iRun26.2]

That is for metal-hydride batteries, which are predecessors to Li-Ion batteries currently being used in laptops.

That's very good to know!

How many people are using the charge limiting software pointed about by the OP? I downloaded it and am running it but it still makes me nervous to use something that would seem nature for Apple to use in their laptops by default (if it works). Is that because it would be too confusing to the general audience?

 

[yukari]

I've been using it for a month or so and have not had any problems. You can monitor using coconut battery or even using System Info on the mac. Does not seem to cause any problems.

I have been keeping mine between 50-60% (typically at 55%) when plugged in. Only when I know I will be traveling or away from a power source I would charge it to 80%. I have not charged to 100% since. I will charge it to 100% if I know I will be using the computer away from a power source for more than 5 hours. But these days, there is a power source nearby no matter where you so.

 

[iRun26.2]

I've been using it for a month or so and have not had any problems. You can monitor using coconut battery or even using System Info on the mac. Does not seem to cause any problems.

I have been keeping mine between 50-60% (typically at 55%) when plugged in. Only when I know I will be traveling or away from a power source I would charge it to 80%. I have not charged to 100% since. I will charge it to 100% if I know I will be using the computer away from a power source for more than 5 hours. But these days, there is a power source nearby no matter where you so.

That sure is different from the norm. But, I suppose, if it really helps out your battery it may be worth it.

When you do need your battery for more than 5 hours, how far do you let it drain down? Do you ever wait for it shut off automatically on you (when it reaches 0%)?

 

[yukari]

That sure is different from the norm. But, I suppose, if it really helps out your battery it may be worth it.

When you do need your battery for more than 5 hours, how far do you let it drain down? Do you ever wait for it shut off automatically on you (when it reaches 0%)?

I try not to let the battery drain below 40%, if I can help it. As you can see from your own source https://batteryuniversity.com/index.php/learn/article/how_to_prolong_lithium_based_batteries it is bad to drain Li-Ion batteries completely. I try to keep it within 40-80% range at all times. But when plugged-in, I will keep it at around 55% for the most part.

 

[iRun26.2]

I never did any of that with my 2015 MacBook (always letting it automatically charge 100% and stay there) and now it's battery is not holding nearly as much of a charge anymore.

 

[yukari]

Also, don't keep it plugged in at night. I use to keep it plugged in all the time. Now when I know I won't be using the computer for more than an hour or so, I shut it down and unplug.

It's a little hassle, but it is definitely a lot better for the battery.

 

[iRun26.2]

Also, don't keep it plugged in at night. I use to keep it plugged in all the time. Now when I know I won't be using the computer for more than an hour or so, I shut it down and unplug.

It's a little hassle, but it is definitely a lot better for the battery.

That's a bummer because I often go to bed with it to do some number crunching overnight (so its ready with the results the next morning).

 

[simonmet]

That's very good to know!

How many people are using the charge limiting software pointed about by the OP? I downloaded it and am running it but it still makes me nervous to use something that would seem nature for Apple to use in their laptops by default (if it works). Is that because it would be too confusing to the general audience?

That, and battery degradation is one of their main tools of obsolescence.

I downloaded the AlDente version and set it to 70. Hopefully my battery hasn’t degraded too much so far. It’s got 21 cycles and 96% health according to the estimate. I’ve seen that figure fluctuate quite a lot however, even as low as 86% at one point.

 

[iRun26.2]

That, and battery degradation is one of their main tools of obsolescence.

Yes, it is! It's one of the reasons I got a new computer (but the fact that the hard drive was gettin full and I needed a much more power machine were more important reasons for an upgrade).
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Is it good to use the battery (within the recommended zone) regularly?

 

[teidon]

It still seems like Apple should have built in software that does this for us.

There isn't built-in software, but these third party charge limiters modifies one System Management Controller (SMC) parameter, and do nothing more. They don't in anyway change or manage the charging of the battery, that all is handled by the system. Apple could easily create a similar application/functionality if they wanted to.

I have always thought (because I think I heard it somewhere) that you should run your computer's battery all the way down once in a while. I guess that's not the case (as, now that I think about it, I should know since I have an electric car! I know they should not be run down to a low value). ?

Deep cycling of Li-Ion batteries is bad, as has already been discussed well enough I think. But there is one reason to deep cycle Li-Ion battery and that is to calibrate the battery indicator. Li-Ion battery's charge level is measured by counting how much the battery has been charged and discharged instead of reading the voltage like could be done with some other type of batteries. That method is inaccurate and over time the battery indicator will give inaccurate value. It could for example say that there is 30% of charge left while in reality there is still 40%. The way to calibrate that is to fully discharge the battery and then fully charge it. But charge levels below 30% and above 80% are bad for Li-Ion so you shouldn't do that often - or ever.

Electric Vehicles (EV) are little different though: their battery is limited between 30% and 80% charge level to maximise the lifetime. So when your car says the battery is full, it's actually only at 80% charge. It also means that the car uses only half of the battery's capacity. The car manufacturer could give you a software update to unlock the full capacity. That would double the mileage, but would end up killing the battery in couple/few years.

 

[coffeeplease]

It is both of them. Battery University says in their article BU-808: How to Prolong Lithium-based Batteries following:





They also have this table with maximum charge levels and how many cycles the battery lasts with each of them (they don't specify if the battery's capacity ends up being 70% or 80% after the cycles):

Charge level (V/cell)	Discharge cycles	Available stored energy
4.20	300–500	100%
4.15	400–700	90–95%
4.10	600–1,000	85–90%
4.05	850–1,500	80–85%
4.00	1,200–2,000	70–75%
3.90	2,400–4,000	60–65%

Based on these I would say that if you are going to use the laptop plugged in, setting the maximum charge level to about 60% would be best. If you instead use it on battery, maximum charge level should be kept below 85%. Also the battery shouldn't go below 30% charge level if you want to maximise its lifetime.

How much of a difference would you think it'd be to do a maximum charge of 80% versus 60% for the mostly plugged in use case? Reason being 80% charge would be the most frictionless for the occasional use off of power adapter.
- 80% to 30% gives you 50% of the battery to use, seems like a good amount
- 60% to 30% gives you 30% of the battery to use, seems smaller than ideal, having to change the maximum charge more often when you know you'd like to go off charger for a little longer

Or perhaps it's just balancing how much laptop use you do off of power adapter. If you know you don't use over 30% battery off of charger most of the time, 60% is good. If more, set a maximum charge somewhere between 60-80%?

There is a graph on there that indicates battery health sitting at 40% versus 100%, but nothing in-between. It suggests holding a lower charge is better. Does this mean if you were to use the battery on charger all the time, 40% is ideal?

Temperature​	40% charge​	100% charge​
0°C	98% (after 1 year)	94% (after 1 year)
25°C	96% (after 1 year)	80% (after 1 year)
40°C	85% (after 1 year)	65% (after 1 year)
60°C	75% (after 1 year)	60% (after 3 months)

 

[teidon]

How much of a difference would you think it'd be to do a maximum charge of 80% versus 60% for the mostly plugged in use case? Reason being 80% charge would be the most frictionless for the occasional use off of power adapter.

I think this statement from that page answers that best:

Most Li-ions charge to 4.20V/cell, and every reduction in peak charge voltage of 0.10V/cell is said to double the cycle life. For example, a lithium-ion cell charged to 4.20V/cell typically delivers 300–500 cycles. If charged to only 4.10V/cell, the life can be prolonged to 600–1,000 cycles; 4.0V/cell should deliver 1,200–2,000 and 3.90V/cell should provide 2,400–4,000 cycles.

The graph on one of my previous posts helps you figure out what each V/cell is in charge level %. They also state that optimal charge for longevity is 3.92V/cell, which is around 60%. I believe this value is when the battery is actually used. But I don’t know if the optimal range is 30%-60% or even less. But in one of their articles they say that NASA’s satellites have max charge of 3.92V/cell which gives their batteries a lifetime of 40 000 cycles. But those batteries might be little more expensive than your typical laptop batteries.

There is a graph on there that indicates battery health sitting at 40% versus 100%, but nothing in-between. It suggests holding a lower charge is better. Does this mean if you were to use the battery on charger all the time, 40% is ideal?

I actually do not understand why they had 40% as one data point because they recommend you to store Li-Ions at 50%. It could be that 40% is better if you can somehow maintain that level. But they also say that lower max charge level than 3.92V/cell (60%) will have detrimental effect on the battery.

But I think the best course of action is to set the max charge level to as low as you can while your typical use cases will never drop the charge level below 30%. If you are going to always have the device plugged in I honestly have no idea what the optimal level is. All I know is that it’s something between 30% and 60%.

 

[iRun26.2]

I think this statement from that page answers that best:


The graph on one of my previous posts helps you figure out what each V/cell is in charge level %. They also state that optimal charge for longevity is 3.92V/cell, which is around 60%. I believe this value is when the battery is actually used. But I don’t know if the optimal range is 30%-60% or even less. But in one of their articles they say that NASA’s satellites have max charge of 3.92V/cell which gives their batteries a lifetime of 40 000 cycles. But those batteries might be little more expensive than your typical laptop batteries.


I actually do not understand why they had 40% as one data point because they recommend you to store Li-Ions at 50%. It could be that 40% is better if you can somehow maintain that level. But they also say that lower max charge level than 3.92V/cell (60%) will have detrimental effect on the battery.

But I think the best course of action is to set the max charge level to as low as you can while your typical use cases will never drop the charge level below 30%. If you are going to always have the device plugged in I honestly have no idea what the optimal level is. All I know is that it’s something between 30% and 80%.

This is really good stuff! Everyone who uses a MacBook on any kind should read this thread.
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What about discharge rate? I'm sure discharging the battery slowly would be best for the battery but I'm curious how bad you think it would be to be going from 80% too 30% in only 1 to 2 hours.

 

[yukari]

...
What about discharge rate? I'm sure discharging the battery slowly would be best for the battery but I'm curious how bad you think it would be to be going from 80% too 30% in only 1 to 2 hours.

I would imagine that everything being equal, going from 80% to 30% in only 1 to 2 hours would cause a drastic temperature increase. Basically faster the discharge = faster the chemical reaction = higher battery temperature.

So it would be bad to discharge at a faster rate.

 

[teidon]

What about discharge rate? I'm sure discharging the battery slowly would be best for the battery but I'm curious how bad you think it would be to be going from 80% too 30% in only 1 to 2 hours.

Fast discharge and charge rates are bad for Li-Ions. For example Android users are so happy to have and eager to use fast charging on their devices but that feature actually kills your battery. But fast discharging is also an issue and especially problematic with MBPs because you might do some serious work on those devices while on battery which will not only discharge the battery rapidly but also elevate the temperature due to heavy CPU/GPU use.

But I do not have an answer right now how bad it actually is. But if possible avoid super fast charging/discharging, high temperatures (over 30°C) and low (below 30%) and high (over 80%) charge levels.

“if possible” meaning that it’s a tool you use for a purpose and the battery is going to fail sooner or later. So when you can, avoid the harmful states, but use the device as intended when you can’t.


EDIT: Fast discharge is bad for Energy Cell kind of Li-Ions, but they have protective circuits to prevent it. Power Cells can be discharged at much higher rate than energy cells.

 

[yukari]

Speed kills. Both on the road and your battery.

 

[teidon]

Fast discharge and charge rates are bad for Li-Ions. For example Android users are so happy to have and eager to use fast charging on their devices but that feature actually kills your battery. But fast discharging is also an issue and especially problematic with MBPs because you might do some serious work on those devices while on battery which will not only discharge the battery rapidly but also elevate the temperature due to heavy CPU/GPU use.

I'll add some more information to this.

There are two types of Li-Ion cells: Energy Cells and Power Cells. Energy cells shouldn't be charged or discharged at higher than 1C rate, and they actually have protective circuits to prevent higher than 1C discharge rate. Power Cells can be charged and discharged at higher than 1C but they have lower capacity. 1C means that if the battery is charged at 1C, it will be full in one hour. And the same for discharging. But in case of Li-Ions, this has slightly different meaning because they have to be charged in two stages. First stage is from 0% to 70% (or how each battery is configured) and is fast. The second phase is from that until full and is slow. Stage 2 charging is also harmful for the battery and is avoided (battery won't be charged to full) in some applications where longevity is important.

The advised charge rate of an Energy Cell is between 0.5C and 1C; the complete charge time is about 2–3 hours. Manufacturers of these cells recommend charging at 0.8C or less to prolong battery life

They have a graph that show charging of Energy Cell from 0% to 4.20V/cell at 1C. It takes 3 hours. During first hour the charge level goes from 0% to over 80%. During the last hour it goes from about 98%/99% to 100%.

So if your device charges from 0% to 100% in less than 2 hours, it might be harmful to the battery. For example Qualcomm's Quick Charge 3+ promises to charge the battery from 0% to 50% in 15 minutes. I think that corresponds to 2C charge rate. If those batteries are Energy Cells, that charge rate is harmful to them. But if they are Power Cells or some kind of crossbreed of the two, that charge rate would be fine.

Charging Lithium-ion
Tweaking the Mobile Phone Battery
Introducing Qualcomm Quick Charge 3+, fast and efficient charging for the masses

 

[Tankmaze]

Well, I just change the swollen battery on my MBP. the toughest part was in the middle.

Now I'm going to charge this to 100% and wait for 2 more hours and then drain and will use the charge limiter to set to 60%.

Thanks to this forum, otherwise I wouldn't know about this little software.

 

[iRun26.2]

I just thought of another thing That may have helped contribute to my previous computer (fan-less MacBook) having a degraded battery condition:

When I left it to go to lunch (or exercise, or whatever) I left it running. Worst of all was that I had a screen saver set up to the run which took lots of CPU power). My laptop was always quite warm when I got back (thus, not good for the battery)!

 

[Supra Mac]

Great thread, thanks to those who posted the links and info. I now have Al Dente and Charge Limiter on our MacBooks. Set to 85% for our use case. Thanks!

 

[magbarn]

Fast discharge and charge rates are bad for Li-Ions. For example Android users are so happy to have and eager to use fast charging on their devices but that feature actually kills your battery. But fast discharging is also an issue and especially problematic with MBPs because you might do some serious work on those devices while on battery which will not only discharge the battery rapidly but also elevate the temperature due to heavy CPU/GPU use.

But I do not have an answer right now how bad it actually is. But if possible avoid super fast charging/discharging, high temperatures (over 30°C) and low (below 30%) and high (over 80%) charge levels.

“if possible” meaning that it’s a tool you use for a purpose and the battery is going to fail sooner or later. So when you can, avoid the harmful states, but use the device as intended when you can’t.


EDIT: Fast discharge is bad for Energy Cell kind of Li-Ions, but they have protective circuits to prevent it. Power Cells can be discharged at much higher rate than energy cells.

I've been fast charging the crap out of my 11 Max since new and it's still 100%. It has been charged repeatedly with Apple's 30 watt USB C adapter at home and Anker's 30 watt USB C charger in the car.
I don't think speed hurts anywhere as much as charge % and temperature.

If it was, Tesla wouldn't be using their supercharging network as they would get slammed with warranty claims.