PRAM and Battery Issues in iBooks and 12″ PowerBooks

Apple made an unusual decision when it designed the original iBook, the one with the handle. Unlike most Macs before and since, iBooks do not have a PRAM battery. Neither does the 12″ PowerBook G4, which is based on the iBook G4. Instead, the parameter RAM (PRAM for short) is maintained by using the charge in the iBook’s battery. 

blueberry iBookFor the sake of convenience, we will use the term iBook or ‘Book to encompass the various iBook models as well as the 12″ PowerBook G4.

iBook PRAM Issues

If you remove your ‘Book’s battery or let it run out of juice, the PRAM loses its settings and your ‘Book will think it’s 1969. That’s the biggest indicator of a dead PRAM battery in most Macs, but in iBooks it means no power is getting to the PRAM.

Instead of a PRAM battery, iBooks have a PRAM capacitor, which can hold a charge for a short while – perhaps 20 seconds – so you can swap out a nearly drained battery for a charged one and not lose the PRAM settings. Sometimes that capacitor goes bad, preventing the PRAM from getting any power at all. If your iBook has a good battery and gives you the wrong date every time you turn it on, you need to replace the PRAM capacitor.

12" iBook G3This is not an expensive part, but it is a difficult project. Disassembling an iBook is a challenge even with the guides from iFixit, and clamshell iBooks are among the most difficult Macs to take apart and get back together successfully.

The part you are replacing is a 0.022F 5.5V capacitor, and iBooks can be a challenge to take apart, especially the clamshell models. You will need to remove the old PRAM capacitor (this page has a good photo of it) and solder in a replacement. If you are not comfortable with challenging disassembly and reassembly, or if you’re not comfortable doing component-level replacement and soldering, get a pro to do it.

Once the PRAM capacitor has been replaced, your ‘Book should remember the time, date, and other PRAM settings unless you let the battery drain too far.

The Power Manager and New Batteries

If your ‘Book has a good PRAM capacitor, that can interfere with your ability to reset the Power Management Unit (PMU). On other Macs, you remove the PRAM battery, but on these ‘Books you can’t – and you certainly do not want to remove the PRAM capacitor.

When you replace an old battery with a new one, you should reset the PMU. Old or incorrect data in the PMU (known as SMC for System Management Controller in Intel-based Macs) can prevent your new battery from charging completely. There’s a two-step process to teaching your ‘Book to forget about the old battery and prepare it for the new one:

  1. Reset the PMU. There is a small reset button “under the grille”. Straighten out the end of a paperclip and hold the reset button down for 5-10 seconds.
  2. Reset the PRAM and/or NVRAM (nonvolatile RAM). Shut down your ‘Book, start it up, and hold down Cmd-Opt-P-R simultaneously until it chimes 3 or 4 times to clear out the old PRAM data.

Some sources recommend using Open Firmware to reset NVRAM, but Cmd-Opt-P-R should always be sufficient. And now your ‘Book will recognize the new battery and calibrate itself with a fresh start because you’ve cleared out all memory of the previous battery.

You can also use Battery Reset 2.0 from Apple, which you can download from my Dropbox account if Apple ever removes its download.

Further Reading

Keywords: #pramcapacitor #clamshellibook #ibookg3 #ibookg4 #12inchpowerbook #12inchpowerbookg4

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