New MacBook Pro performance degrades with the battery removed

New MacBook Pro performance degrades with the battery removed

Summary: Gearlog has discovered a weird issue with the latest generation (Late 2008) MacBook Pros – they run like dogs when the battery is removed. To the tune of a 37-percent drop in speed without the battery.



Gearlog has discovered a weird issue with the latest generation (Late 2008) MacBook Pros – they run like dogs when the battery is removed. To the tune of a 37-percent drop in speed without the battery.

Zach Honig benchmarked a 2.53GHz MacBook Pro with Maxon's Cinebench R10. With a battery the MacBook Pro scored 5,549, without 3,504.

An Apple support article (HT2332) claims that the performance drop in both the MacBook and MacBook Pro "prevents the computer from shutting down if it demands more power than the A/C adaptor alone can provide." It also warns again using the notebooks without the adaptor connected because "accidentally bumping the A/C adaptor could disconnect power and shutdown the computer."

Why would anyone want to use a MacBook without the battery, anyway?

(Tip: Chuck Freedman, Wired Gadget Lab)

Topics: Laptops, Apple, Hardware, Mobility

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  • They run even slower with the CPU pulled.

    Infact, pull out the hard drive motherboard and RAM and it virtually stops working.
    • Re: No CPU


      But, after removing those items, dropping them from a tall building speeds them back up. In fact, they get faster the further they fall. But talk about a bad computer crash if you disengage the buffer at the bottom.
      Software Architect 1982
      • They fall faster than windows boxes

        Typical Apple product -- their better aerodynamic shape gives them a higher terminal velocity than a Windoze box. Obviously this is part of Jobs' evil plan to get us to buy more macs.
  • RE: New MacBook Pro performance degrades with the battery removed

    Why without the battery? Simply because if you use the laptop as your main computer and it spends 99 percent of the time on your desk, it makes sense to remove the battery. Batteries have only limited lifespan, every re-charging takes a little bit of life out of them.

    It also improves cooling/heat dissipation.

    Many shops have their demo Macbooks on wihtout batteries, for the above reasons + it deters some thieves.

    My MacBook Pro runs on AC only. But it's previous generation 2.4 GHz model.
    • Actually...

      ...the batteries degrade faster if they are not used. I have an HP Laptop about 2 years old, when I stored it last December it had a battery life of about 2-2.5 hours. When I took it out in August the battery was dead, I got about 5 minutes of use after a 24 hour charge. I called HP and (since it was out of warranty) they said the battery needed to be replaced at a cost of (I believe) $140 including S&H.
      • That's one anecdotal experience, not statistical evidence

        The fact is, research has shown that batteries degrade more rapidly when they become hot. Sitting in a notebook for hours at a time is a very hot environment.

        Li/ion Batteries degrade more quickly when they are stored with a full charge. Furthermore, they also can fail (for different reasons) if stored in a fully discharged state.

        When planning to store a battery for an extended period of time, you should store it at half charge or less, in a cool environment.

        Li-ion battery life is generally 2-3 years. In your case, your battery was already near the end of its life when you stored it. It's hardly surprising that it failed.
        • Good site.

          I've bookmarked it for future reference. When I stored my notebook I followed HP's advice ( although it looks a little different from last year) and left the battery at 50% charge. It was in my office, kept at around 19-20 degrees Celsius so I can only assume you are correct that the battery had reached it's end. What I find annoying about that is that I still have an HP Jornada 820, purchased in 1998, and it still has an over 8 hour battery life 10 years later. When I got it, it had a 12 hour battery life. I now have a CF card which I didn't use then, so how much of the battery life is taken by writing to the CF card is a mystery, however it seems a bit annoying to me that a 33% drop in battery life can't be matched by modern technology.
  • Another reason to run without a battery

    Although not a Macbook, once while on a plane I wanted to use one of those 12V inverters that can power a notebook. Unfortunately the inverter kept cutting out because it did not have enough power available. Actually I am not sure if it was the inverter or the airplane's 12V outlet that kept cutting out, but either way the laptop was drawing too much power. On a whim I decided to remove the battery and see if that would help. It did, as the inverter no longer needed to charge the batter in addition to powering the laptop.

    Yes, and end case but still, removing the battery helped in this case.
  • When the battery Dies?

    What about when the battery has died or is intermitant?

    If the problem is the power adapter does provide enough juice then all these mac book owners could be experiancing a lot of problem in a couple of years.
  • RE: New MacBook Pro performance degrades with the battery removed

    I call shenanigans! If the macbook truly draws more power than the AC adapter can supply, then it draws too much power to CHARGE an installed battery while running!! I bet they have the power management set up to reduce performance in order to save battery life as the detected battery charge drops, and thus it sees no battery and drops performance to minimum levels.
    • Ever hear of a surge?

      Like when the laptop needs to spin-up the CD/DVD? A pretty lame design decision if true though.
    • It does.

      I have a MacBook Pro, and the battery will not charge if the machine is very busy, for example running Visio in a virtual machine. If I get into the office and run Visio, the battery won't charge, it will stay at the same amount of time remaining. If I plug it in and leave it be (running only Thunderbird and Firefox for example) the battery will charge, usually pretty quickly. So my conclusion is that the MacBook Pro will run on it's power supply but can't charge the battery if it's being stressed. If it's not being taxed heavily, it uses the extra power to recharge the battery. I can only assume that if it's being stressed beyond what I have experienced, it draws on the battery for additional power.
      • Not abnormal for a rechargeable device...

        my cellphone's manual clearly states that even if plugged in,
        it will not charge while in use.
  • Not a macbook but...

    A couple of years ago my girlfriend's daughter bought a store-demo laptop because it was a top-end laptop for like 75% off. Problem was, it didn't have the battery.

    What with one expense and another she's never had the spare cash to buy one.

    That's just one reason to run a laptop w/o a battery. Another might be the battery died and you don't have the money to replace it.

    Not as big a problem for most Mac owners, natch, but what about second-hand machines gifted from a relative? Might very well come without a battery.

    Seems to me Apple is blowing smoke about "pulling more power than the wall power can provide". The plug in power supply can't handle the load????

    That's definitely a corner cutting move of the Micky Mouse variety.
  • That's the stupidest thing I've read here...

    [i]prevents the computer from shutting down if it demands more power than the A/C adaptor alone can provide.[/i]

    Demands more power than the AC adapter requires???

    Good grief!

    If an 110V AC outlet with power brick can't power a MacBook by itself normally, then that's pretty sad... Either that or whoever wrote that (HT2332) article is a moron
    hasta la Vista, bah-bie
  • Long standing conventional wisdom

    O.K., gang, I'm not prepared to defend Apple's argument to the death, but it's long standing convention wisdom that: 1) you shouldn't run your laptop without a battery and 2) you shouldn't leave the battery on charge at all times.

    As for CW #1, I know that a lot of people have been getting away with it. No doubt, most of us do. E.g., IBM's mainframes use Thinkpads as "support elements" (SE's) mounted inside the cabinet and running software which monitors and manages the "big iron", The SE's don't have batteries installed, meaning that the battery compartments are empty. I think this means that what it comes down to is on that, on model-by-model basis, it depends on what power parameters were used by the EE's who designed the machine's power systems. Apple's EE's evidently decided on a power model which requires the battery for assured operation at full power demand. Alternatively, they screwed up the design, but in any case, power management has been deliberately set up to cut power consumption if the battery is removed

    As for #2, all I can say is that people are obviously getting away with it. I thought that was what the charging circuitry was for. Most batteries can quick charge up to about 80% capacity, then the charging current has to be reduced or the battery will overheat.

    I leave the battery in, especially while running, because I don't want a power blip to ruin my day. But I don't have to leave the machine plugged in all day, either. I don't think a laptop is meant to be a 24/7 system. I have a desktop for that.
  • No, not 'degrade'... it running in Apple "Green" mode. And use the typical weasel words like "polished" "refined" "elegant" to describe it...
    Feldwebel Wolfenstool
  • RE: New MacBook Pro performance degrades with the battery removed

    Considering the incredible graphics
    chips in this machine..two I do
    believe, it is not a surprise to me that
    they had to compromise somewhere
    for otherwise they would have to build
    a heavy and hot power supply into
    the AC adapter. One normally runs a
    laptop with a battery if for no other
    reason than to be assured that it is in
    essence running in UPS mode. This
    experiment might be interesting but it
    sure would not stop me from buying
    this fine professional laptop nor
    should it influence anyone. It is more
    a curiosity and reflects rather on how
    much muscle the graphics chips must
    have as the entire thing is pulling
    power for a reason.
  • Why would anyone want to use a MacBook without the battery, anyway?

    Hmm interesting question. Let's call it a day than. we have
    had battery recalls in the past, I personally have had two
    batteries that were blown up in a MacBook Pro, of course
    apple will replace them but it takes them at least here over a
    month. Than there is little choice than using it without the
  • Ya don't say...

    Oh big deal! The same goes for your car, cell phone, mp3
    player remote controls I'm sure there aren't any articles
    stating the fact for those products. :-p