Every Mac has a small battery which will need replacing occasionally. It’s easy to spot when it needs replacing because the special memory known as the Parameter RAM, or PRAM (pronounced Pee-Ram) has forgotten its previous settings.
The PRAM is used to store some system and application settings that are not stored in the Preferences folder. They are settings needed at system startup time, before the System and Finder have been found and loaded. If the battery’s flat it can’t remember the previous settings when you turn your Mac on.
The Common Symptoms
If your Mac is roughly 5 years old (eg Classic, LCIII or Performa 400 vintage) and you suddenly notice that several settings keep changing every time you restart, then it’s likely that your PRAM battery is flat.
• date is wrong (eg 1956) • time is wrong (eg about midnight)
• time zone has been forgotten • AppleTalk has been turned turned on
• the StyleWriter has stopped working • EtherTalk networks reset to LocalTalk
• Mouse movements seem sluggish • memory 32-bit addressing has turned off
• you are left with just a few MB of memory • Folder protection settings change
• the startup sound happens twice, not once • display settings (some Macs) changed
• PowerBook settings have changed
Not all these symptoms will happen to your Mac and not all of them happen every time. The date and time symptom and inability to print are probably the first things you will notice.
Saving Good PRAM Settings
As an interim measure, until you get the battery replaced, you can manually reinstate all the settings that go wrong each time you turn on your Mac. But you may find that a tool like TechTool (on cover CDs) useful because it can save your PRAM settings and you can quickly restore them at a later date (repeatedly). There’s no option but to manually reset the date and time, TechTool isn’t clairvoyant.
Types of PRAM Battery
There are several kinds of battery used in Macs, so check to see what kind you have. You can get details from Apple’s Internet site (details below) or simply take out the old battery and show it to a store owner.
What Models?
This article focuses on just one type of PRAM battery, the 3.6V Lithium type used for many Macs that are likely to need a new battery about now.
Without opening them all up (let alone owning them all) I think the SE/30, Classic, Classic II, Colour Classic, Colour Classic II, IIx, IIcx, IIci, IIsi, IIvi, IIvx, IIfx, LC, LC II, LC III, LC 475, LC 520, LC 550, TV, Performa 2xx, 4xx, 520, 550, 560, 600, 611x, Centris 610, 650, 660AV, Quadra 605, 610, 650, 660AV, 700, 800, 840AV, 900, 950, PowerMac 6100, 7100, 7200, 7215, 7300, 7500, 7600, 81xx, 8200, 85xx, 8600, 95xx, 9600 all use the same 3.6V Lithium battery. Some Macs, such as the IIfx require two.
The safest bet is to crack open your Mac (not literally) and have a look.
Flipping Your Lid
I’ll tell you about “pizza-box” Macs, like the LC series and the older Performas, because they’re the one’s that seem to be prone to losing their juice at the moment. How to get into your every kind of Mac is an article in its own right.
You’ll see from the diagram below that you’ll need to remove a screw and ease a pair of tabs before you can lift the lid off a “pizza box”. I assume you’ll be standing towards the front of the Mac.
 
With the lid off, you’ll see a green circuit board smothered in electronic components.
Finding the Battery
Somewhere on the circuit board will be a stubby battery inside a plastic battery housing (or two for some Macs). This illustration shows you what to look for.
 
Accessing the Battery
To remove the battery you’ll need to pop the lid off the the battery holder. This is where a biro cap comes in useful - a Biro cap is less likely to scratch the circuit board than a screwdriver if you are ham-fisted. Batteries may be cheap, but Mac circuit boards aren’t. Take care.
 
The object of the Biro cap is to unlatch the tabs of the upper part of the battery holder from the base, first at one end and then the other end. It may take you several attempts - I found it easy on one Mac and difficult on another.
Removing the Battery
Once you have the lid off the battery holder, notice which way around the old battery is. You should find a (+) sign at one end and similar marking on the base of the holder when you remove the battery.
Buying a New Battery
This article is predominantly aimed at owners of a particular kind of Mac - the kind with a 3.6 Volt Lithium battery that’s half the length of a standard AA battery. Beware though, there’s a 1.5 Volt battery that looks very similar and it’s not a suitable replacement.
As it’s not the most popular of batteries, you are unlikely to find it in high street shops and market stalls. It is however available from Apple dealers (part number 742-0011), electronic component suppliers such as RS Components (professional) and Maplin Electronics (hobby). The battery costs about a little more than a fiver from Maplin Electronics (part number GS99H).
If you have trouble locating a supplier, and need to quote a manufacturer’s model number, one of Hitachi Maxell ER3S, Tadiran TL5101 or TL2150, Electrochem 3B26, Ternacell T04/41, Varta VL1/2AA or Radio Shack 23-026 (Tandy) should do the trick.
Fitting the Replacement
As the car manuals say, replacement is the reverse of removal. Put the new battery in the correct way (there’s a + and - in the base!), put the battery cover back on, then finally put the lid of the Mac back on and you’re away. What happened to that screw at the back? Oops. Lost it.
Too Wimpish?
Frank hates shopping so is reluctant to get the battery for you. He will however tell you where you can find an Apple dealer or Maplin Electronics store, then lend a hand to fit the battery.
Apple dealers are happy relieve you of the pain and strain of DIY for about £20.
Setting Things Up Again
No matter who fits the battery, you’ll need to correct your settings afterwards. If you copied your PRAM settings with TechTool before the battery went flat, then you can reinstate them easily. If not, you’ll have to do the job manually.
Getting More Information
For more information about Mac batteries, Apple’s Tech Info Library article 11751 at til.info.apple.com will be helpful, as will the Apple Spec Database at Apple Software Updates area of ftp.info.apple.com. The Macintosh Battery Web site www.academ.com/info/macintosh/ may also be worth a visit.
InformINIT (on cover CDs) gives detailed descriptions of what the Parameter RAM stores and what gets “zapped” when the battery goes flat.
This article is the copyright of Macintosh & Apple Computer Users Society [MaCus]. It has been made available to you for your personal use in the hope that you find it useful. If your interests are of a commercial nature you should contact MACus, or email their secretary DavJaeger@tesco.net
