Welcome To The Macintosh Battery Web Page!

These pages began when I wanted to answer the question - "How do I replace my logic board battery?" (but they also document some other useful or interesting battery information).

This question often follows the question - "Why is it that when I boot my Macintosh, the monitor is set to "Black and White" and the date is wrong?"


These pages are NOT designed to show the user how to dismantle their computer. A lot of that information has been included and more is being added all the time - but the pages were made possible by my clock-chipping activities. There are other sites that do provide some more of that information; see the links at the bottom of this page.


The first symptom of this problem is frequently when your desktop Mac does not want to start. This can be a sign that the SoftPower circuit is not getting enough power from the battery to start the Mac (the battery also handles ADB control and the SoftPower circuit). But this is often not recognized as a battery problem.

Thanks to Richard Hill for the information about the ADB and SoftPower circuit.

The classic symptom is when a Mac starts up in Black and White (the Monitors control panel is set to Black & White), with the date set in 1956.

If this happens and you are on an early model you will probably also be in 24 bit addressing mode.

Don't Get Fooled By Similar Symptoms!

Sometimes people will see a similar symptom and think they have battery problems, for instance when the Mac boots up with a Black and White startup screen but then reverts to color. When this happens - delete your Finder preferences and restart, your Finder preferences are probably corrupt.

If your Mac shuts down unexpectedly - the PRAM can get corrupted and this can cause the Mac to fail to start up, just like it has a bad battery. If this has happened, you may have to start up and zap the PRAM on start-up. Just restart and hold down these keys: Option-Command-P-R. And yes, the Command key is the one with a "pretzel" on it. The better way to zap the PRAM is with TechTool (see the link below) but if your Mac won't start up you should restart and zap PRAM, then go back and use TechTool later.

Another cause for the failure to start up is a bad card - if your Mac refuses to start, remove any accelerator, etc cards and try to start up. The card may have failed.

Battery Sources

Go here for pages that give battery sources in various countries.

Desktop Macintoshes

A Photo Of A BatteryFirst, what do the batteries in most of the desktops look like?

The batteries are under a "cage" - that you have to get off before you can replace the battery. It is not easy to describe this cage - here is a picture of one: View From The Top

And here is one flipped over: View From The Bottom

The batteries are almost exactly one inch (25 mm) long, with the silver button on the top counted in.

What kind of batteries are these?

  • 3.6 volt Lithium batteries.
  • The red and silver one is a Maxell Super, model ER3S (1/2 AA)
  • The purple one is a Tadiran Lithium Inorganic Battery, model TL 5101
  • The Radio Shack part number is 23-026
  • Many Quadra/Performas and PowerMacs have a completely different kind of battery - here is how David Maffucci (Visionary@li.com) of Visionary Computers described it:

    I have the info about the Quadra 630 Battery. It is a Rayovac 840, 4.5V
    Alkaline battery. It is nothing like the other 3.6V batteries, this one
    is a big square looking thing that is attached to the Logic Board with
    velcro. It is also about twice the price of the 3.6V battery.

    Thanks David!

    And now you can buy a Rayovac 841- a revision of the battery that is a bit cheaper. Thanks to Jerold Wallis for telling me about the new battery. The Rayovac 844 is also a suitable substitute.

    If you are going to change your battery, I suggest you use something like TechTool to save your PRAM settings - when you pull the battery out, the PRAM is all set to zero. This includes the "secret" parts of the PRAM that store the number of hours it has been on, the date it was finished, etc.

    To get a copy of TechTool, click here.

    How do you replace these 3.6 volt batteries?

  • First make sure you are well grounded.
  • Next take the cover off of the Mac. (For many Macs - this is NOT trivial. For some models such as the LC it is very simple and no instructions are really necessary.)
  • Next make sure you are still well grounded.
  • Next touch the power supply with both hands to bleed off any residual static electricity.
  • Look at the battery cage - pry it out and up from one end and it should come off. You can also squeeze it in the middle and that will frequently widen the ends enough that they don't grip the bottom of the cradle.
  • Put the cage off to the side.
  • Note which way the battery is facing. There is an impression on the bottom of the battery holder that shows which way the battery should be oriented. You can see it when you get the battery out.
  • Pull the old battery out.
  • Put the new battery in FACING THE SAME WAY THE OLD ONE WAS!
  • Replace the battery cage.
  • Put the Mac cover back on (or however you got access to the logic board).
  • Plug it in, turn in on.
  • Reset the Monitors control panel to color, double click speed, etc.
  • Reset the date and time, and check that you are in 32 bit addressing.
  • Safely dispose of the old battery.
  • The 4.5 volt alkaline battery just unplugs from the logic board.

    Battery Locations For Specific Mac Models:

    The Classic Mac

    The early versions of the all-in-one Mac (for instance the Plus) use a 4.5 volt alkaline battery that I am told is easy to access and change. There is a panel in the back that you pop open.

    The SE and similar form factor computers that I have seen all use the 3.6 volt Lithium battery, and you have to disassemble the computer to get to the battery. Not only is it more difficult to get to the battery but you are also going into the monitor as well. You run the risk of getting a nasty shock when you work near the monitor; for that reason it is better to take these to a repair shop.


    The subordinate page has photos of the insides of a 2si - showing the battery location and what the battery looks like. Click here to go to the page showing the 2si.


    Between my page and a terrific page out there maintained by "shobaffum" that this page now links to, for the ci information (and it also applies to the cx and even the Q700) there is a lot of information about these available. With this source, replacing batteries should be very easy. Their batteries are not soldered to the logic board.

    Click here to go to the page showing the 2cx and 2 ci.

    II, IIx, IIfx

    These appear to be odd critters, with two batteries.

    Click here to go to the page with a photo of the 2fx.

    All-In-One Macs (MacTV, LC520, LC 550, and many other 68k and PPC Performas)

    The All In One is a great example of how to design computers for easy maintenance and the subordinate page has several photos showing their batteries and how to access the components.

    LC Series/Quadra 605

    The LC, LC II, LC III, and LC475/Quadra 605 (and related Performas) are all excellent examples of the "slab" version of the Mac - the case has a much lower profile than a 2cx or a Quadra 630. It is real simple to get the logic board out - and easy to clock chip them (well, for the LC III and the Quadra 605 anyway).

    With a dead battery, these often fail to start up at all - you may hear the hard drive spin for a moment, but the screen remains black.

    Click here to go to the page with the photos of the LC series.

    Quadra/Performa 630 Series

    This series (called the 630 or the 635 or the 636 or 637) has the 4.5V alkaline battery instead of the 3.6V lithium. It is held on the logic board with velcro. The subordinate page has lots of information about this model.

    For the 630-form factor owners out there, see the Cautionary Tale page for an alert about some similar symptoms that indicate a more serious problem.

    Centris/Quadra 650

    The battery on this model is on the front, right corner of the logic board (if you are facing the front of the computer like you were going to use it), just under a bracket that holds the floppy drive. If you have an internal CD drive - the battery is just under it.

    Centris/Quadra 660AV Series

    The photos of a Centris 660AV are courtesy of Mike Rine.

    And here is the page with the photos - so you can see that it uses a 3.6 volt lithium..

    This model of the Mac accelerates quite well - from 25 MHz to easily 33 Mhz, and does not require any logic board soldering.

    Quadra 700

    The Quadra 700 is a ci turned into a tower, and you have to remove several components to get to the battery. But after removing a single screw, these components all snap in and out, and the battery is our old pal the 3.6 volt lithium. There are some good photos of this model on the subordinate page; the Mac belonged to my niece, Teresa.

    Click here to go to the page showing the Quadra 700.

    Quadra 950

    The Quadra 950 tower is very easy to maintain - the battery is the 3.6 volt lithium and it will be visible on the front edge of the logic board. The front panels (called bezels) also come off very easily - take off the bottom one first. See the photos for directions.

    Click here to go to the page illustrating Quadra 950 maintenance.

    PowerMac 6100 Series

    The PowerMac 6100 (the example used is a 6115CD) looks like a version of the low profile Mac. The battery is easy to get to - although it is under a couple of wire bundles.

    Click here to go to the page with the photo of the PowerMac 6115CD.

    PowerMac 6214CD

    My brother has a PowerMac 6214, and it is very easy to work on. The User's Guide even shows you how to get the logic board out! The 4.5 v alkaline battery is very recognizable - but the velcro definitely holds on to it. This Mac's logic board design cripples it's performance, but it is still a good, basic, Mac.

    Click here to go to the page with the photo of the PowerMac 6214CD.

    PowerMac 7100 Series

    The PowerMac 7100 (these photos are a 7100/66, courtesy of Rob Lane) has a battery that is accessible from the side of the Mac. It uses the 3.6 volt lithium battery rather than the 4.5 volt alkaline.

    Click here to go to the page with the photo of a PowerMac 7100.

    PowerMac 7200 Series

    The PowerMac 7200 is as easily maintained as almost any Mac. See the PowerMac page for some maintenance steps and a photo of the battery.

    PowerMac 8100 Series

    The 8100 has the lithium battery, see the PowerMac page (linked above) for the information I have so far.

    UMAX SuperMac C500

    The UMAX C500 is NOT easily maintained. See the UMAX Clone page for some maintenance steps and a photo of the battery.

    UMAX SuperMac S900L

    The UMAX S900L is also not as easy to maintain as an Apple-designed Mac. See the UMAX Clone page for some maintenance steps.

    PowerMac G3 Desktop

    The G3 desktop has a case that is very similar to the 7200 that was described above. Just use those directions in PowerMac page to access the battery.

    The iMac

    This Mac uses the 3.6v lithium battery. The authors of the c't site have contributed a wonderful photo of it: The Battery In An iMac

    For all of the information that you could ask for on the iMac, visit The iMac Page There you will find out all about the various models - with upgrade directions!

    Power Computing

    This site: Power Computing Information does a much better job than I can at supporting these. They were great computers and the company really did a lot to keep the Macintosh alive when Apple ads were pathetic. They will not be forgotten!


    The Powerbook information is on this page.

    It covers the:

    Powerbook 100, 140, 145, and 170, Powerbook 520/540, (and slightly) the 1400, 5300, and Outbound (Mac Clone)

    For the Powerbook 500 series, J B Cole has built a page that answers all your questions, so I just link to his.

    Other Links That Can Help You

    Since many of us have older Macs - the Low End Mac page is a natural place to look for advice. On this page, Dan Knight supports quite a few varieties of Macs.

    There is a great place for service in Huntsville, Alabama - the Mac Resource. They have their own building - it is right off of University, across the street from a Baymont Inn and is behind the Country Inns and Suites. The address is 1570 The Boardwalk; their phone number is (256) 721-1700 and you can email them by clicking here. Their web site is: Mac Resource.

    A place for service or batteries is Refurb Madness - click here. They are in Rockford, Illinois but sell batteries by mail order. I have not bought anything from them but they sound reasonable.

    If you are in New York City - a good place to get batteries and maintenance is Tekserve, 163 West 23rd Street. For info contact David Lerner david@tekserve.com or see their web page at www.tekserve.com. Their phone is 212-929-3645 (voice) and 212-463-9280 (fax).

    If you are lucky enough to have a Powerbook - see the link to O'Grady's page on the Powerbook page.

    Related Trivia

    So why do different Macs reset to different dates?

    Most Macs reset to Aug 27th, 1956. As it turns out, this is the birthdate of one of the designers, Ray Montagne, who apparently designed the CUDA microcontroller. This chip controls the PRAM and ADB on many models. Peter Werner found that information on the Nov 95 MacUser Help folder.

    By the way, Steve Jobs was born in 1955, so the date is not his birthday. Other Macs reset to the default date - the date that the clock shows when the clock registers are filled with zeros. The date is Jan 1, 1904.

    Rick Holzgrafe tells why some Macs reset to that odd year - the question was "What is the default date if the clock contains all zeros?" His answer:

    It's midnight, Jan 1, 1904. This date was selected because the original Mac's clock (which counts in seconds) can encompass a period of about 136 years. Selecting 1904 as the start date means that the 136-year period covered by the clock (1904-2040) includes the birthdate of nearly every Mac user, and extends well past the expected lifetime of the Mac OS. It also means that the simplest rule for leap-years can be used (every fourth year has an extra day), which simplifies day and date calculations. They didn't choose the year 1900 because it was not a leap year, and so would have complicated matters. To thank him for providing the answer to the question that had so many people wondering, I included a link to his shareware page. Rick has written some great improvements (such as The Tilery) to for our (pre-OS X) Macs. Thanks Rick!

    Safely Disposing Of Batteries

    The lithium batteries should be recycled; for a link to my extensive Recycling and Household Hazardous Waste web pages which can help find a place to recycle them, click here . Many Radio Shack locations take them back. Some places do accept alkaline batteries but you'll have to do some looking to find one.

    As of May 2, 2003

    Interested in how I did these pages (I have gotten a lot of questions about that)? Click here

    Errors are entirely the fault of the author, email me with comments. The author has no connection to Apple, Radio Shack, any battery company, or anyone else listed here.

    Your Macintosh Logic Board Battery Information Source

    Charles D Phillips
    If you want to, you can send me mail. AOL users - please type your email address in your message - AOL doesn't always send the right address so I can't just reply to your message.

    Thanks to Stan Barber for hosting these pages.

    This page and all photos on it are copyrighted by Charles Phillips. You may refer to this page and information on it - with proper attribution.