After I had some batteries on Apple products die on me (and had to spend obscene amounts of money replacing them, because on top of Apple repairs being expensive, my country has some of the highest tax rates in the world piled on top), and being an electrical engineer, I decided to do some research on the scientific literature with regards to what could prolong the battery lifetime. Here is the executive summary:
1. Temperature: the main killer of batteries. Do everything on your power to keep the computer (and hence the battery) as cool as possible. For instance, using your phone for navigation in the car, which by itself heats the phone a lot due to GPS usage, plus having the sun shining directly on it, is just awful. If you do this often, try to leave the phone in the shade or right in front of the car's A/C vents to cool it. The inductive chargers I'm familiar with dissipate a lot of heat so I don't use those for the iPhone.
2. State of charge (battery percentage) and depth of discharge. Batteries degrade faster if fully charged. Some of the research indicates they'll also degrade if nearly depleted, and it appears a good compromise is about 60% charge. Too bad Apple won't allow you to connect the power adapter but disable charging (more on that at the end of the post). It might be very useful for those who don't need the full battery range, like me. Also some of the research indicates, as pointed out in the article, you should have shallow depths of discharge, i.e. 5 discharges from 60% to 40% are better than 1 discharge from 100% to 0%, although technically both are counted by the gas gauge IC as 1 cycle.
3. Charge rate. Try to charge the device as slowly as possible. Although the research isn't clear on the point of diminishing returns, one thing is certain: fast charging is harmful to the battery, so avoid it (the worst example being USB-C to an iPhone). This is probably what kills Apple Pencils so quickly -- at least the 1st gen, non-inductive-charging one (I speak from experience, having had one replaced with 9 months of very light use on it). I wouldn't even recommend using the iPad 12 W charger, but rather the iPhone 5 W one, even to charge the iPad. An interesting trick: you can use your iPad USB-A charger plus a USB-A to USB-C cable to charge the newest MacBooks very slowly if not in use (if in use, it'll at best maintain the charge with very light use, or deplete it at moderate to heavy use).
4. Cycle count. Best thing to do would be not to put in the cycles if possible, although if points 1 and 2 are not respected, even a battery that hasn't been cycled at all will eventually die. This one is simple: try to connect the charger as often as is feasible. Even if you're taking it out for a quick half-hour session, leave the charger connected. For MacBooks, there are also some settings to be used with the pmset command in Terminal to make sure the computer goes to standby, since it is not unusual to lose 10% charge (i.e. 1/10 of a cycle) over less than a day if you close the lid but don't go to standby. The computer will take a bit longer to wake up but depending on your usage patterns, it pays to do this since it could add up to as much as 30 cycles a year, which is far from negligible -- it's about half what I put on my computer over a year of use.
I have written an app for MacBooks that is able to keep the computer at the desired charge level with the power adapter connected but not charging. I use it to keep my computer at 60% charge following point 2. I thought of releasing the app, but I'm certain that as soon as I do it, someone at Apple will take notice and close the API I use to do it (same reason why I'm being intentionally vague here). The point is, the capability is there, but Apple has a long history of stopping at nothing to prevent users from doing legitimate things with the devices they paid hard-earned cash for. This same API could be used on iOS but unfortunately it requires root access and I'm not willing to jailbreak my phone over it, if it's even still possible.
Hope this helps someone.
1. Please try a little bit of formatting, like paragraphs and newlines. They are useful to the reader
2. I only want to contest Point 3-charge rate. I have used my ipad air 2 charger on my iphone 6 through out its life, and after 4yrs of daily usage the iphone6 battery still has 91% capacity. And I live in tropical areas, so no cooling benefits either. So, I think the faster charging causing degradation of battery is just a myth.
1. I did. For some reason every post I’ve made on AppleInsider eats up my formatting. I’ve also broken this answer into two paragraphs after the next sentence, but I’m pretty sure it’ll eat the newline.
2. Like I said, the research isn’t clear on the point of diminishing returns. Within Apple’s lineup, the only clear battery-killer is charging the 1st gen Apple Pencil via the iPad’s Lightning port, which fully charges the Pencil in about 15-20 minutes — so a 3C to 4C charge rate not factoring in inefficiencies, so perhaps even 5C. It’s no surprise people replace those every year. This is why I charge my Pencil exclusively using the little adapter that came with it to plug into a Lightning cable — this way a full charge takes 1h20m or so. Other than that, the closest one comes to an excessive charge rate would be fast-charging an iPhone X or iPhone XS using a USB-C PD charger. Still, in my opinion, a slow charge is an extra precaution that I don’t mind taking — if I leave my iPhone on the iPhone charger before going to sleep, rather than on the iPad charger, I’ll wake up to a full battery either way, so what’s the downside? Also, this ensures the phone spends fewer hours at 100% which is knowingly harmful to the battery, and also that it heats up less while charging, which is also harmful. Maybe it makes very little difference, but like I said, I don’t see the downside.
My mid 2015 15in MBP is normally on mains power all the time.
Sounds logical that's less "wear" for the battery (and for you it shows), but is this generally recommended? Or maybe once in a while using the battery?
From the article: "If you're doing this, you're not letting the battery deplete, you are
off-and-on recharging it a tiny, tiny bit at a time. It's been a long
time since we had NiCad batteries where this would degrade them over
time -- and this behavior in this day and age won't harm the battery to
any appreciable level."
The answer to my question isn't in the article, it's not about off-and-on recharging, my question is about keeping the battery always charged and connected...
It is, though. When the cable is plugged in constantly, this is what you're doing. Tiny, tiny discharges and recharges.
How far back does this go? My MacBook Pro 3,1 battery seemed to not like the machine being powered by adapter 100% of the time. I don’t travel much, so my habits are to keep my devices plugged in and disconnect and discharge them every now and then to keep the chemistry going. Did Apple’s battery management become more sophisticated after that? My 2009 MacBook Pro 5,5 battery seems to have lasted twice as long as BOTH user-serviceable batteries in the 3,1 model.
After I had some batteries on Apple products die on me (and had to spend obscene amounts of money replacing them, because on top of Apple repairs being expensive, my country has some of the highest tax rates in the world piled on top), and being an electrical engineer, I decided to do some research on the scientific literature with regards to what could prolong the battery lifetime. Here is the executive summary:
1. Temperature: the main killer of batteries. Do everything on your power to keep the computer (and hence the battery) as cool as possible. For instance, using your phone for navigation in the car, which by itself heats the phone a lot due to GPS usage, plus having the sun shining directly on it, is just awful. If you do this often, try to leave the phone in the shade or right in front of the car's A/C vents to cool it. The inductive chargers I'm familiar with dissipate a lot of heat so I don't use those for the iPhone.
2. State of charge (battery percentage) and depth of discharge. Batteries degrade faster if fully charged. Some of the research indicates they'll also degrade if nearly depleted, and it appears a good compromise is about 60% charge. Too bad Apple won't allow you to connect the power adapter but disable charging (more on that at the end of the post). It might be very useful for those who don't need the full battery range, like me. Also some of the research indicates, as pointed out in the article, you should have shallow depths of discharge, i.e. 5 discharges from 60% to 40% are better than 1 discharge from 100% to 0%, although technically both are counted by the gas gauge IC as 1 cycle.
3. Charge rate. Try to charge the device as slowly as possible. Although the research isn't clear on the point of diminishing returns, one thing is certain: fast charging is harmful to the battery, so avoid it (the worst example being USB-C to an iPhone). This is probably what kills Apple Pencils so quickly -- at least the 1st gen, non-inductive-charging one (I speak from experience, having had one replaced with 9 months of very light use on it). I wouldn't even recommend using the iPad 12 W charger, but rather the iPhone 5 W one, even to charge the iPad. An interesting trick: you can use your iPad USB-A charger plus a USB-A to USB-C cable to charge the newest MacBooks very slowly if not in use (if in use, it'll at best maintain the charge with very light use, or deplete it at moderate to heavy use).
4. Cycle count. Best thing to do would be not to put in the cycles if possible, although if points 1 and 2 are not respected, even a battery that hasn't been cycled at all will eventually die. This one is simple: try to connect the charger as often as is feasible. Even if you're taking it out for a quick half-hour session, leave the charger connected. For MacBooks, there are also some settings to be used with the pmset command in Terminal to make sure the computer goes to standby, since it is not unusual to lose 10% charge (i.e. 1/10 of a cycle) over less than a day if you close the lid but don't go to standby. The computer will take a bit longer to wake up but depending on your usage patterns, it pays to do this since it could add up to as much as 30 cycles a year, which is far from negligible -- it's about half what I put on my computer over a year of use.
I have written an app for MacBooks that is able to keep the computer at the desired charge level with the power adapter connected but not charging. I use it to keep my computer at 60% charge following point 2. I thought of releasing the app, but I'm certain that as soon as I do it, someone at Apple will take notice and close the API I use to do it (same reason why I'm being intentionally vague here). The point is, the capability is there, but Apple has a long history of stopping at nothing to prevent users from doing legitimate things with the devices they paid hard-earned cash for. This same API could be used on iOS but unfortunately it requires root access and I'm not willing to jailbreak my phone over it, if it's even still possible.
Hope this helps someone.
1. Please try a little bit of formatting, like paragraphs and newlines. They are useful to the reader
2. I only want to contest Point 3-charge rate. I have used my ipad air 2 charger on my iphone 6 through out its life, and after 4yrs of daily usage the iphone6 battery still has 91% capacity. And I live in tropical areas, so no cooling benefits either. So, I think the faster charging causing degradation of battery is just a myth.
By the way, here’s some relevant data from the literature:
2012 15" Retina MBP at 1427 cycles. Obviously doesn't hold a charge like she used to (I can get 2 to 3 hours unplugged and it no longer gives me a warning if it's about to power off), but still works perfectly otherwise. Battery status message is still only at "Replace Soon." Would cost $199 to replace the battery but my model is only worth about $350 on eBay with a good battery, so I'm trying to hold off until Apple shrinks them bezels. [cue "Something's Coming" from West Side Story]
The Apple Genius Bar tech in Charlotte, NC just told me “keeping your MacBook Pro connected to its charger all the time wears out the battery much faster”.
Your article is timely as I just submitted my maxed out MacBook Pro 2016 15” with the expanding battery problem yesterday for service - no the serial number didn’t match that of any active Apple recall. Fortunately, I paid for Apple Care Plus which is about to expire in November. This notebook is used mostly as a business desktop replacement connected to two 4K monitors. However, I need it for travel multiple weeks at a time over the course of each year for related work.
The Apple Genius Bar tech in Charlotte, NC just told me “keeping your MacBook Pro connected to its charger all the time wears out the battery much faster”.
Your article is timely as I just submitted my maxed out MacBook Pro 2016 15” with the expanding battery problem yesterday for service - no the serial number didn’t match that of any active Apple recall. Fortunately, I paid for Apple Care Plus which is about to expire in November. This notebook is used mostly as a business desktop replacement connected to two 4K monitors. However, I need it for travel multiple weeks at a time over the course of each year for related work.
Who has the facts and who should I believe?
The genius is wrong, and giving you advice that was out of date about a decade ago.
My mid 2015 15in MBP is normally on mains power all the time.
Sounds logical that's less "wear" for the battery (and for you it shows), but is this generally recommended? Or maybe once in a while using the battery?
From the article: "If you're doing this, you're not letting the battery deplete, you are
off-and-on recharging it a tiny, tiny bit at a time. It's been a long
time since we had NiCad batteries where this would degrade them over
time -- and this behavior in this day and age won't harm the battery to
any appreciable level."
The answer to my question isn't in the article, it's not about off-and-on recharging, my question is about keeping the battery always charged and connected...
It is, though. When the cable is plugged in constantly, this is what you're doing. Tiny, tiny discharges and recharges.
How far back does this go? My MacBook Pro 3,1 battery seemed to not like the machine being powered by adapter 100% of the time. I don’t travel much, so my habits are to keep my devices plugged in and disconnect and discharge them every now and then to keep the chemistry going. Did Apple’s battery management become more sophisticated after that? My 2009 MacBook Pro 5,5 battery seems to have lasted twice as long as BOTH user-serviceable batteries in the 3,1 model.
After I had some batteries on Apple products die on me (and had to spend obscene amounts of money replacing them, because on top of Apple repairs being expensive, my country has some of the highest tax rates in the world piled on top), and being an electrical engineer, I decided to do some research on the scientific literature with regards to what could prolong the battery lifetime. Here is the executive summary:
1. Temperature: the main killer of batteries. Do everything on your power to keep the computer (and hence the battery) as cool as possible. For instance, using your phone for navigation in the car, which by itself heats the phone a lot due to GPS usage, plus having the sun shining directly on it, is just awful. If you do this often, try to leave the phone in the shade or right in front of the car's A/C vents to cool it. The inductive chargers I'm familiar with dissipate a lot of heat so I don't use those for the iPhone.
2. State of charge (battery percentage) and depth of discharge. Batteries degrade faster if fully charged. Some of the research indicates they'll also degrade if nearly depleted, and it appears a good compromise is about 60% charge. Too bad Apple won't allow you to connect the power adapter but disable charging (more on that at the end of the post). It might be very useful for those who don't need the full battery range, like me. Also some of the research indicates, as pointed out in the article, you should have shallow depths of discharge, i.e. 5 discharges from 60% to 40% are better than 1 discharge from 100% to 0%, although technically both are counted by the gas gauge IC as 1 cycle.
3. Charge rate. Try to charge the device as slowly as possible. Although the research isn't clear on the point of diminishing returns, one thing is certain: fast charging is harmful to the battery, so avoid it (the worst example being USB-C to an iPhone). This is probably what kills Apple Pencils so quickly -- at least the 1st gen, non-inductive-charging one (I speak from experience, having had one replaced with 9 months of very light use on it). I wouldn't even recommend using the iPad 12 W charger, but rather the iPhone 5 W one, even to charge the iPad. An interesting trick: you can use your iPad USB-A charger plus a USB-A to USB-C cable to charge the newest MacBooks very slowly if not in use (if in use, it'll at best maintain the charge with very light use, or deplete it at moderate to heavy use).
4. Cycle count. Best thing to do would be not to put in the cycles if possible, although if points 1 and 2 are not respected, even a battery that hasn't been cycled at all will eventually die. This one is simple: try to connect the charger as often as is feasible. Even if you're taking it out for a quick half-hour session, leave the charger connected. For MacBooks, there are also some settings to be used with the pmset command in Terminal to make sure the computer goes to standby, since it is not unusual to lose 10% charge (i.e. 1/10 of a cycle) over less than a day if you close the lid but don't go to standby. The computer will take a bit longer to wake up but depending on your usage patterns, it pays to do this since it could add up to as much as 30 cycles a year, which is far from negligible -- it's about half what I put on my computer over a year of use.
I have written an app for MacBooks that is able to keep the computer at the desired charge level with the power adapter connected but not charging. I use it to keep my computer at 60% charge following point 2. I thought of releasing the app, but I'm certain that as soon as I do it, someone at Apple will take notice and close the API I use to do it (same reason why I'm being intentionally vague here). The point is, the capability is there, but Apple has a long history of stopping at nothing to prevent users from doing legitimate things with the devices they paid hard-earned cash for. This same API could be used on iOS but unfortunately it requires root access and I'm not willing to jailbreak my phone over it, if it's even still possible.
Hope this helps someone.
I had an Apple Pencil too at one time, and I can agree with you that fast charging this device is a complete no-no. Thank you also for the great insights on the state of charge. I've learnt a lot.
Comments
2. Like I said, the research isn’t clear on the point of diminishing returns. Within Apple’s lineup, the only clear battery-killer is charging the 1st gen Apple Pencil via the iPad’s Lightning port, which fully charges the Pencil in about 15-20 minutes — so a 3C to 4C charge rate not factoring in inefficiencies, so perhaps even 5C. It’s no surprise people replace those every year. This is why I charge my Pencil exclusively using the little adapter that came with it to plug into a Lightning cable — this way a full charge takes 1h20m or so. Other than that, the closest one comes to an excessive charge rate would be fast-charging an iPhone X or iPhone XS using a USB-C PD charger. Still, in my opinion, a slow charge is an extra precaution that I don’t mind taking — if I leave my iPhone on the iPhone charger before going to sleep, rather than on the iPad charger, I’ll wake up to a full battery either way, so what’s the downside? Also, this ensures the phone spends fewer hours at 100% which is knowingly harmful to the battery, and also that it heats up less while charging, which is also harmful. Maybe it makes very little difference, but like I said, I don’t see the downside.
Your article is timely as I just submitted my maxed out MacBook Pro 2016 15” with the expanding battery problem yesterday for service - no the serial number didn’t match that of any active Apple recall. Fortunately, I paid for Apple Care Plus which is about to expire in November. This notebook is used mostly as a business desktop replacement connected to two 4K monitors. However, I need it for travel multiple weeks at a time over the course of each year for related work.
Who has the facts and who should I believe?
Content: 95%
Legibility: -100%