what is the secret to good battery health?

[m85476585]

Discharging it partially hurts. Always try to do a full discharge and consequent full recharge.

That is incorrect. Maybe true for NiCD batteries, but not Lithium ones.

Ugh I hate reading these battery care threads. I always end up more confused than when I started.

That is because most people that post in them don't know what they are talking about. Although I'm not an expert either (and I don't claim to be one). A lot of the confusion in this thread comes from misinformation or misunderstanding.

Here is an article written by an expert:
http://www.batteryuniversity.com/parttwo-34.htm

A lithium-ion battery provides 300-500 discharge/charge cycles. The battery prefers a partial rather than a full discharge. Frequent full discharges should be avoided when possible. Instead, charge the battery more often or use a larger battery. There is no concern of memory when applying unscheduled charges.

The worst condition is keeping a fully charged battery at elevated temperatures, which is the case with running laptop batteries. If used on main power, the battery inside a laptop will only last for 12-18 months. I must hasten to explain that the pack does not die suddenly but begins with reduced run-times.

To read this thread, you have to filter out the noise. Posts backed up by expert sources are generally good, as long as what the poster is saying matches the source, and as long as the source is reputable. Anecdotal evidence is OK, but take it with a grain of salt. If it matches up with what other people are reporting and matches what the experts say, it is probably valid.

 

[Syvere]

The battery degrades with each charge cycle but also heat.
The absolute best way for maximum life span is to keep it in fixed power and cool place. Laptop coolerpad might be a good idea for example or some sort of elevator/dock so that the back of the laptop gets more airflow.

It doesn't matter if you keep the laptop on fixed power when it's turned off.

 

[BeachChair]

Theres not much magic to it, my Macbook Unibodys batteri is 1.5 years old and its still in pretty good shape. It has lost maybe 20-30%.

A lithium ion batteri under normal use looses about 20% pr year. How much it looses depends mainly on the temperature its kept at, the colder the better.

 

[MacGiver]

I honestly believe that it was a special case for your 2007 mbp. Iv actually heard the opposite that keeping the mbp plugged in is better than to continuously uncharging and charging the battery.

I know that once in a while it is good to completely discharge the battery and fully recharge.

Not sure who told you that but it is very well known that alaways leaving a laptop on the mains will kill the battery overtime...The best is to charge it when the battery gets low not necessarly to 0%...

 

[Mew2468]

I use my MacBook Pro for about 3 - 5 hours a day. For 2 days I run my laptop plugged in and on the 3rd day I run it down to around ~45% - ~55%. Is this a good way to use my battery? Should I be discharging it more?

 

[jjahshik32]

Avoid frequent full discharges because this puts additional strain on the battery. Several partial discharges with frequent recharges are better for lithium-ion than one deep one. Recharging a partially charged lithium-ion does not cause harm because there is no memory. (In this respect, lithium-ion differs from nickel-based batteries.) Short battery life in a laptop is mainly cause by heat rather than charge / discharge patterns.

Batteries with fuel gauge (laptops) should be calibrated by applying a deliberate full discharge once every 30 charges. Running the pack down in the equipment does this. If ignored, the fuel gauge will become increasingly less accurate and in some cases cut off the device prematurely.

Keep the lithium-ion battery cool. Avoid a hot car. For prolonged storage, keep the battery at a 40% charge level.

Consider removing the battery from a laptop when running on fixed power. (Some laptop manufacturers are concerned about dust and moisture accumulating inside the battery casing.)

Avoid purchasing spare lithium-ion batteries for later use. Observe manufacturing dates. Do not buy old stock, even if sold at clearance prices.

If you have a spare lithium-ion battery, use one to the fullest and keep the other cool by placing it in the refrigerator. Do not freeze the battery. For best results, store the battery at 40% state-of-charge.


I guess you were right MacGiver, well now I know. =)

Too bad that the uMBP's battery cannot be taken out..

http://www.batteryuniversity.com/parttwo-34.htm

 

[Erasmus]

Well, FWIW, I've completely torched my battery. iStat Pro reports 66% health after 282 cycles, but that's irrelevant, because the battery gives up and the computer shuts down once the battery drops below ~95% charge, lol. Completely useless as a notebook now. Just bought a new battery from eBay, should get it tomorrow.

What I've done that I believe has destroyed my battery is:
1) Leaving it plugged in for months over holidays
2) Putting the hot notebook straight in my hot bag and leaving it there for hours
3) Using the notebook while in its case on the train for hours (like a clamshell)
4) Watching movies while lying on my bed
5) Not calibrating the battery for months and months

I therefore agree with the statement that heat kills Li-Poly batteries faster than anything else. Under my torture, my battery survived probably about 18 months, before I'm guessing cells began to completely die.

So, I think I need a cooling pad.

 

[Syvere]

Not sure who told you that but it is very well known that alaways leaving a laptop on the mains will kill the battery overtime...The best is to charge it when the battery gets low not necessarly to 0%...

Absolutely totally wrong. Recharge cycles and heat kill the battery. Leaving it on fixed power and ensuring proper cooling during use is the best you can do for the battery. Read the academy research. Leaving it on main while not in use also has no effect. These are NOT old NiCD batteries.

However it is true that small recharges are better than deep charges.

 

[m85476585]

Absolutely totally wrong. Recharge cycles and heat kill the battery. Leaving it on fixed power and ensuring proper cooling during use is the best you can do for the battery. Read the academy research. Leaving it on main while not in use also has no effect. These are NOT old NiCD batteries.

However it is true that small recharges are better than deep charges.

It's true that leaving it plugged in won't over charge the battery, but it will hold the battery at 100% charge, which will eventually (over several months) reduce the health.

Most of the problems with NiCd batteries come from "dumb" chargers that don't shut off when the battery is full. Leaving it plugged in overnight just once could kill a NiCD with a dumb charger.

 

[jdmposer]

the secret is to not worry about it.

my blackbook has 192 cycles and the health is 100%

 

[Pax]

the secret is to not worry about it.

my blackbook has 192 cycles and the health is 100%

+1

To other posters. READ the Battery University article..... quote:- "The question is often asked, should the laptop be disconnected from the main when not in use? Under normal circumstances, it should not matter with lithium-ion. Once the battery is fully charged, no further charge is applied"

My 2006 Whitebook has 300+ cycles on it and the battery is still 90+%. It spends 90%+ of its time connected to the charger.

Just use the damn thing

 

[Azathoth]

Here is an article written by an expert:
http://www.batteryuniversity.com/parttwo-34.htm


To read this thread, you have to filter out the noise. Posts backed up by expert sources are generally good, as long as what the poster is saying matches the source, and as long as the source is reputable. Anecdotal evidence is OK, but take it with a grain of salt. If it matches up with what other people are reporting and matches what the experts say, it is probably valid.

Along with the (good) link above. I'll just add that I've been using my Thinkpad T60 (LiIon) daily for office and home use for about 2+years. I tell the utility SW to only charge to 80% and normally don't discharge below 20%.
The computer runs quite cool normally (<30deg)

After 28months use (180cycles), my battery is at about 96% capacity.
I run the battery cal about once every 6 months.

I don't know how SL handles charging, but if possible:
Keep your computer cool (<30C)

Don't discharge below about 15%

Keep the thing running at >90% for long periods of time

 

[Syvere]

It's true that leaving it plugged in won't over charge the battery, but it will hold the battery at 100% charge, which will eventually (over several months) reduce the health.

Not true. These newer chargers let the battery charge drop to about 80%-90% before recharging it again. This is one of the reasons why the battery charge level isn't 100% even if you have let it charge 24/7.

 

[mrsir2009]

If you just don't worry about it it will work itself out... No point worrying

 

[enberg]

This may be of interest. An actual scientist weighs in.

http://thisweekinbatteries.blogspot.com/2010/02/pull-plug-your-battery-will-thank-you.html

 

[TheRenfro]

I purchased my MacBook in September 2007, almost 2.5 years ago. Not only is my laptop kept on about 80% of the day, it stays plugged in about 95% of the time (even when it's turned off). According to iStat Pro my Battery Health is at 97% after 1020 cycles, not bad for a battery that is always plugged in.

 

[m85476585]

I purchased my MacBook in September 2007, almost 2.5 years ago. Not only is my laptop kept on about 80% of the day, it stays plugged in about 95% of the time (even when it's turned off). According to iStat Pro my Battery Health is at 97% after 1020 cycles, not bad for a battery that is always plugged in.

How did you get 1020 cycles if it's always plugged in?

 

[TheRenfro]

How did you get 1020 cycles if it's always plugged in?

Beats me. For the first year it was unplugged a lot cause I was finishing up college. But for the last year and a half it normally stays plugged in. I unplug it twice a day minimum, from bedroom to home office and back. I also unplug it to go from my office to the toilet.

I don't know how iStat Pro calculates a cycle but I know I haven't gone below 10% battery life 1020 times. I don't think i've seen the "You only have 8 minutes of battery life left" message in 2 months or so.

 

[Pax]

Beats me. For the first year it was unplugged a lot cause I was finishing up college. But for the last year and a half it normally stays plugged in. I unplug it twice a day minimum, from bedroom to home office and back. I also unplug it to go from my office to the toilet.

I don't know how iStat Pro calculates a cycle but I know I haven't gone below 10% battery life 1020 times. I don't think i've seen the "You only have 8 minutes of battery life left" message in 2 months or so.

I think Apple defines a cycle as only a very small discharge, a few percent I think. So you could definitely be doing 1-2 cycles per day.

 

[Syvere]

This may be of interest. An actual scientist weighs in.

http://thisweekinbatteries.blogspot.com/2010/02/pull-plug-your-battery-will-thank-you.html

It depends on the charger actually. However it's still funny how even researchers can't agree on this:
The question is often asked, should the laptop be disconnected from the main when not in use? Under normal circumstances, it should not matter with lithium-ion. Once the battery is fully charged, no further charge is applied.
http://www.batteryuniversity.com/parttwo-34.htm

 

[Pax]

Interesting. As previous poster spotted, this quote

"What you do need to know is that if you keep your laptop plugged in, you force your battery to remain at 4.2V continuously and these side reactions continue to happen and slowly kill the battery."

contradicts Battery University's quote http://www.batteryuniversity.com/partone-12.htm

"No trickle charge is applied because lithium-ion is unable to absorb overcharge. A continuous trickle charge above 4.05V/cell would causes plating of metallic lithium that could lead to instabilities and compromise safety. Instead, a brief topping charge is provided to compensate for the small self-discharge the battery and its protective circuit consume. Depending on the battery, a topping charge may be repeated once every 20 days. Typically, the charge kicks in when the open terminal voltage drops to 4.05V/cell and turns off at a high 4.20V/cell."

So they both agree that trickle charging causes problems, but they disagree about whether laptops trickle charge or not. Now it may be that the first guy doesn't understand laptop batteries - remember he is from electric vehicles where trickle charging is less likely than for a laptop.

My MBP seems to follow the profile in the Battery University article exactly.
- It charges like crazy for a couple of hours,
- then drops to 220 mA and sits there for a few hours
- then charging drops to zero mA.
- It stops at just under 4.2 V per cell
- then the voltage per cell drops very slowly, a few mV per hour (I've only watched for a couple of hours)

I think it's true that a Mac does not keep charging the battery indefinitely and so the Battery University comment seems true:- leaving the Mac on the charger will not damage the battery. I am confident that if I watched my battery for a few days the voltage would drop slowly and then the charger would kick in for an hour or so.

 

[gwsat]

Not sure who told you that but it is very well known that alaways leaving a laptop on the mains will kill the battery overtime...The best is to charge it when the battery gets low not necessarly to 0%...

I routinely left my old Powerbook G4 plugged in unless I was actually away from home. Although the battery charge indicator always indicated that it was at 100%, when my grandson started to routinely use it on the battery, after I had replaced the PB G4 with a MB Pro, he discovered that the battery would die within a very few minutes. Nevertheless, I don't know how significant my grandson's experience may be in the context of this thread because the battery was 5 years old at the time. Anyway, I got a replacement battery for the G4 for about 50 bucks and it provides plenty of life now.

The best tip I have seen was in Apple's own battery maintenance tips, which another poster linked to earlier in the thread:

"Apple recommends charging and discharging its battery at least once per month. Need a reminder? Add an event to your desktop’s iCal."

Because I always do what the smart money boys in Redmond tell me )), I have today started to discharge both my MBP's and PB G4's batteries and placed a monthly recurring reminder in iCal to keep doing it on this day of each following month.

 

[m85476585]

I think Apple defines a cycle as only a very small discharge, a few percent I think. So you could definitely be doing 1-2 cycles per day.

A cycle is defined s a full discharge. If you discharge it to 50% that counts as half a cycle. If you discharge to 90%, that counts as 10% of a cycle.

I think it's true that a Mac does not keep charging the battery indefinitely and so the Battery University comment seems true:- leaving the Mac on the charger will not damage the battery. I am confident that if I watched my battery for a few days the voltage would drop slowly and then the charger would kick in for an hour or so.

That is correct. The battery does stop charging when it is full. However, when it discharges below 95% (I think), the laptop will charge it back up to 100%. Leaving it plugged in won't immediately damage the battery (like a continuous trickle charge would), but over time the battery will lose capacity because it is effectively being stored at or near 100% charge and not being used.

 

[Hellishness]

from reading hundreds of pages over the summer on this, the sole best thing, reported by many, many, many users, is to charge it up, let it die, and repeat. Leaving it on the charger indefinitely is very bad for it. charging it partially and re-charging doesn't really matter unless you do it daily.

i know that the bold statement is hard to believe, and i still have a hard time believing it.

 

[zipa]

i know that the bold statement is hard to believe, and i still have a hard time believing it.

That's good, since it isn't true.