Take the 2-minute tour ×
Super User is a question and answer site for computer enthusiasts and power users. It's 100% free, no registration required.

I'm quite new to Mac and OSX. I have my MacBook Pro now for about 4 month and I know there are a lot of battery-related questions around. I just noticed that after 4 month I have the following battery info:

Cycles: 47
Health: 98% (coconut info)
Condition: normal

I would have the possibility to take the batterie out when I'm working long time with my MacBook and I have the power adapter attached.

What do you usually do? Do you take the battery out?? What are some good/best practices for keeping battery life as long as possible??

On my old HP notebook I used to take battery out when having the power adapter plugged in and when working for a long time. And after 4 years I still have about 1.5 to 2 h battery. What about with Macs?

Hope there's no identical dupe on superuser.

thx

Edit:
Actually, is it normal that I have already a health % of 98%, after 4 month and a cycle count of 47?? I really do pay attention to how I use the battery...probably it's therefore...

Edit 2:
Now, after 2 days I posted here, I have the following statistic:

Cycles: 48
Health: 96% (coconut info)
Condition: normal

That cannot be normal??

share|improve this question
1  
If you have a MBP that's 4 months old, you can't even take the battery out without a lot of shenanigans anyway. –  Daniel Huckstep Sep 23 '09 at 16:56
1  
Not MacBook-specific: "Should laptops remain plugged in when their battery is 100% charged?" at superuser.com/questions/12838/… and "Is it better to use laptop on battery or on AC power?" at superuser.com/questions/12358/… Some performance benchmarks with and without the battery installed at tomshardware.com/news/… –  Arjan Sep 24 '09 at 7:49
    
@darkhelmet I can...got the model just before the new series (damn..but Mac newbie..so) –  Juri Sep 24 '09 at 8:41
add comment

6 Answers

Just consider how much time, comfort and money you loose if you have to take the battery out each time, especially if you happen to accidentally unplug that MagSafe connector. No Safe Sleep then! And if you ever plan to get a new MacBook you won't even be able to take out the battery without using a screwdriver.

Enjoy your MacBook, don't worry about the machine.

(Some performance benchmarks with and without the battery installed at Tom's Hardware. And there's a good reason to completely charge and discharge your battery every now and then for calibration, as that tells the chip on the battery how good your battery is, allowing for better estimates and maybe even for better charging programs.)

share|improve this answer
    
This quote is the best advice in the thread: "Enjoy your MacBook, don't worry about the machine." Personally, I plug my MacBook in until it's 100% then unplug it until it gets down to ~10% and cycle it like that. Since I never use my laptop sitting at a desk, this sort of cycling is trivially easy. –  kubi Sep 24 '09 at 13:08
add comment

There are a lot of different opinions here (I somehow guess it already).

I think this is also quite interesting which I found here (thx SidneySM for the link)

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.

I always assumed that full discharge/charge cycles are better than just discharging to 40% then recharging again etc..

So it's still quite inconclusive what will be "best" rather than laboratory conditions like storing it at 0° at a 40% charge level which of course doesn't hold in practice.

Summarizing the main points you mentioned...

  • The battery should be discharged to some level and possibly also be recharged without becoming fully empty
  • At least once per month a full discharge/recharge cycle should take place if this didn't happen already
  • Having the battery out will reduce clock speed
  • don't use the battery when there is no need (using the battery will of course lower it's life)

(I left the "Apple doesn't recommend..." out because I have the feeling they don't recommend it due to the potential power loss I'm of course aware of.)

I guess this really depends on preferences whether to take the battery out or not. The main important thing is to respect the 4 points above.
However, by having a look at the different sources you mentioned, it seems intuitive that taking the battery out when having your Mac running for a long time doing non-cpu intensive tasks will be good for your battery since it isn't exposed to the heat inside the notebook case. Taking the battery out for a too long time however at 100% charge won't be good either (see point 2 above)..

share|improve this answer
add comment

There's a lot of misinformation here.

  1. Taking the battery out of your computer will limit its performance, as Apple warns in HT2332, and will remove the UPS-effect that the battery gives you (i.e. without the battery, bumping the power cable will shut down the computer immediately).

  2. Leaving the battery in the computer, charged, will shorten its life. To summarize the linked page:

    • The ideal "storage" conditions for your battery are a 40% charge at room temperature.

    • The worst conditions for your battery, in which it will fail the fastest, is a 100% charge at a high temperature. This is the state of the battery when it's sitting in your computer.

    While having a battery in the computer all the time is best for you and the computer, it's worst for the battery. I would recommend taking the battery out if the computer's going to be sitting idle for a while (overnight, while you're at work) and isn't doing anything processor-intensive, and leaving it in otherwise.

Summary: Leaving the battery in the computer all the time will shorten its live. Using the battery also shortens its life. Compromise, and don't use the battery when you don't have to.

share|improve this answer
    
nice views, thanks –  Juri Sep 23 '09 at 18:35
    
Apple charging circuitry will not keep the battery charged at 100%. –  Richard Hoskins Sep 23 '09 at 18:37
    
@Hoskins But I guess 98% won't make the difference... –  Juri Sep 23 '09 at 19:23
    
What's the point of taking the battery out of an idle computer? (I guess that would be the same as unplugging the charger, and shutting the MacBook down.) –  Arjan Sep 24 '09 at 7:55
    
Arjan, by "idle" I mean "idle and awake" or "doing something not processor intensive and awake." –  Sidnicious Sep 24 '09 at 19:25
add comment

Apple recommends not using a MacBook Pro without a battery, since it reduces processor speed when using only the AC adapter to “prevent the computer from shutting down if it demands more power than the A/C adaptor alone can provide.” You also run the risk of bumping the AC adapter and accidentally shutting down the computer, losing all your unsaved data. They also don’t recommend leaving it plugged in all the time:

Apple does not recommend leaving your portable plugged in all the time. An ideal use would be a commuter who uses her MacBook Pro on the train, then plugs it in at the office to charge. This keeps the battery juices flowing. If on the other hand, you use a desktop computer at work, and save a notebook for infrequent travel, Apple recommends charging and discharging its battery at least once per month.

In conclusion, just use it normally, letting it charge and discharge regularly. You should also calibrate your battery from time to time.

share|improve this answer
add comment

Clock speeds on some Macbooks and Macbook Pros are limited without the battery installed. This is to prevent the wallwart from being overtaxed during short periods of high activity.

If your Macbook Pro is such a machine, be aware that you will be limiting your processing speed if you take the battery out, and leaving yourself open to data loss if power is interrupted.

Apple recomends that you do not use a Macbook or Macbook Pro without a battery installed.

Apple uses lithium-ion batteries in their notebooks, which do not suffer from being kept in the machine.

share|improve this answer
    
didn't know that it influences clock speed, thx. Ok, of course if power is interrupted I'll potentially loose data, but I'm just speaking about battery life. Would it help preserving battery life or wouldn't it cause any changes? On my old HP notebook I used to take battery out when having the power adapter plugged in and when working for a long time. And after 4 years I still have about 1.5 to 2 h battery –  Juri Sep 23 '09 at 16:49
1  
Taking your battery out does not improve your battery life. –  Nerdling Sep 23 '09 at 17:01
1  
@Juri You should read about lithium-ion batteries. Perhaps Wikipedia. There is a lot of folk wisdom about batteries that are not true for lithium-ion batteries. I can't say that your Macbook Pro battery is going to last as long as your HP notebook battery, but I can say that leaving it in your Macbook Pro will not shorten its life. –  Richard Hoskins Sep 23 '09 at 17:13
add comment

Modern batteries are no longer affected by the "memory effect".

I personally leave my battery in, and the charger on.

If there are any sort of power cuts, you are protected.

The battery discharges and recharges a minimal amount of power and I wouldn't worry about it.

share|improve this answer
    
The battery won't be charged until it drops below a cushion threshold, to avoid charging too frequently. I'd say it's around 90%. Leaving your battery in doesn't hurt, and in fact, is how the laptop is made to function. LEAVE IT IN. –  Nerdling Sep 23 '09 at 17:00
add comment

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.