My mid-2009 13" unibody MacBook Pro died years ago. It's probably not worth fixing. I'm just curious if a dead CMOS/PRAM battery could have caused its demise?

iFixIt doesn't list any non-primary batteries in its online store or replacement guides for any unibody Macbook Pros.

Did these models lack one altogether or was it just soldered to the logic board (In which case it'd be kind of like planned obsolescence) ?

  • 1
    A dead PRAM battery will lose the date & time. I'm not sure what else it holds the power to. I've only experienced it on old Mac Pros, which can exhibit very odd behaviour if the battery is flat [fortunately, they use the cheap-as-chips CR2032 & are very easily replaceable]
    – Tetsujin
    Sep 29, 2021 at 8:08

1 Answer 1


I don't know the precise details on this, per model, but the general rule of thumb is if the main battery is removable on a Macbook [Pro] then it has either a "CMOS" battery or a super capacitor.

I'm pretty sure the Unibodies had the super capacitor, which assuming it still works is powered by the regular charging process. If it's failed, even after a good couple of main battery cycles on the charger, the primary symptom is probably that the date keeps resetting. It should still boot, though I saw mentioned in one site that it may not if it's cold.
I'd check that before investigating further.

I found this on iFixit - https://www.ifixit.com/Answers/View/394346/MacBook+Pro+13%22+Mid+2009+what+capacitor+I+need

  • "if the main battery is removable" There are unibodies with removable batteries?!
    – MWB
    Sep 29, 2021 at 9:44
  • That would have been pretty simple to google - store.ifixit.co.uk/products/…
    – Tetsujin
    Sep 29, 2021 at 9:45
  • It's not "removable".
    – MWB
    Sep 29, 2021 at 9:46
  • 2
    You need to do some of your own research on this, as every time I tell you something with definable reference, you fail to "believe" it. Yes, any Macbook since about 2013 has a soldered non-replaceable battery. Also soldered non-replacable or upgradeable RAM & GPU too.
    – Tetsujin
    Sep 29, 2021 at 10:30
  • 1
    There's essentially 3 categories of battery-replacement on MacBooks. 1) User-Replaceable, where it was just clicked in (latch or coin-mechanism to swap it out), 2) Tech-Replaceable, where the battery is screwed in, but is a separate part, these could theoretically be swapped by the user but parts can't just be bought from the shelf and warranty would be voided (these are still considered and called "replaceable"), and 3) the ones that are glued in (usually to the Top Case), these are typically called non-replaceable (although of course, you could still get them out and glue in a new one) Sep 29, 2021 at 15:11

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .