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#34166 - 05/08/15 04:22 PM Is there an internal battery in the iMac 5K Retina
jchuzi Online


Registered: 08/04/09
Loc: New York State
I'm used to being concerned about the internal backup (PRAM) battery in my old G4 and Mac Pro (I replaced it in both, eventually). I know that Apple claims that, except for memory, there are no user-replaceable parts in my iMac 5K Retina. I am concerned that replacing the battery would necessitate a trip to Apple.

I looked at the listing in MacTracker, and it says (under Connections):

POWER

Backup Battery --


Since the newest iMac listed with such a battery is the 20-inch Late 2006 model, may I assume that subsequent models do not have it?

MacTracker has the following listing for the above:

POWER

Backup Battery 3 V Lithium (922-6476)


If there is no battery in later iMacs, what has Apple done to maintain PRAM settings when the computer is shut down?
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Jon

OS 10.14.2, iMac Retina 5K 27-inch, late 2014, 3.5 GHz Intel Core i5, 1 TB fusion drive, 16 GB RAM, Epson SureColor P600, Photoshop CC, Lightroom CC, MS Office 365

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#34167 - 05/08/15 06:30 PM Re: Is there an internal battery in the iMac 5K Retina [Re: jchuzi]
joemikeb Offline
Moderator

Registered: 08/04/09
Loc: Fort Worth, Texas
The Backup Battery (a.k.a. PRAM Battery) disappeared from all desktop Macs beginning in 2009. It is not as clear with the laptops as the PRAM was kept charged by the main battery in some models (the iBook) as early as 1999. I am not privy to Apple's design internals, but I have always assumed they went to an EEPROM (electronically erasable programable read only memory) or similar device that does not require a continuous source of power to retain the data stored on it. It makes a lot more sense than relying on a battery that will inevitably have to be replaced and according to McGillicudy's Corollary to Murphy's Law will invariably occur at the worst possible time.
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#34169 - 05/09/15 02:00 AM Re: Is there an internal battery in the iMac 5K Retina [Re: joemikeb]
jchuzi Online


Registered: 08/04/09
Loc: New York State
It's good to know that, Joe. I always thought that having the battery was not a good way to go. BTW, both McGillicudy and Murphy were optimists. wink
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Jon

OS 10.14.2, iMac Retina 5K 27-inch, late 2014, 3.5 GHz Intel Core i5, 1 TB fusion drive, 16 GB RAM, Epson SureColor P600, Photoshop CC, Lightroom CC, MS Office 365

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#34172 - 05/09/15 07:41 AM Re: Is there an internal battery in the iMac 5K Retina [Re: jchuzi]
joemikeb Offline
Moderator

Registered: 08/04/09
Loc: Fort Worth, Texas
The technology for storage devices that do not require continuous power has been around since probably the mid 50s, but they were expensive, could take several minutes to update or change, and were slow to read. However technology marches on and those disadvantages have largely been overcome in newer devices and thus we now have SSDs replacing HDs. My crystal ball is notoriously cloudy and has a few cracks in it, but with continued development I believe RAM and data storage (Solid State Drives) will merge into a single solid state device probably as part of the CPU and without some of the limitations of the current generation of SSDs.

There is new technology (quantum transistors) currently in the engineering stage of development, that offers the potential of PetaByte memory/storage capacity built into the CPU chip itself.
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#34173 - 05/09/15 07:45 AM Re: Is there an internal battery in the iMac 5K Retina [Re: joemikeb]
jchuzi Online


Registered: 08/04/09
Loc: New York State
I'll believe in new technology when my aging brain can be replaced by a SSD. tongue
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Jon

OS 10.14.2, iMac Retina 5K 27-inch, late 2014, 3.5 GHz Intel Core i5, 1 TB fusion drive, 16 GB RAM, Epson SureColor P600, Photoshop CC, Lightroom CC, MS Office 365

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#34176 - 05/09/15 09:46 AM Re: Is there an internal battery in the iMac 5K Retina [Re: jchuzi]
joemikeb Offline
Moderator

Registered: 08/04/09
Loc: Fort Worth, Texas
Originally Posted By: jchuzi
I'll believe in new technology when my aging brain can be replaced by a SSD. tongue

I believe in what I see and I have seen a prototype of the device I mentioned. They were a long way from becoming a product but I have also seen Jack Kilby's original chip prototype in Texas Instrument's South Building lobby and what I am talking about was further along than Kilby's prototype was in its time and that was ten or fifteen years ago. Your brain replacement may be closer than you think! grin


Edited by joemikeb (05/09/15 09:47 AM)
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#34186 - 05/11/15 04:40 AM Re: Is there an internal battery in the iMac 5K Retina [Re: joemikeb]
Virtual1 Offline


Registered: 08/04/09
Loc: Iowa
Desktop macs still have a battery though, to maintain the clock when the computer is unplugged from power. But that has nothing to do with PRAM parameter storage. I think they use a CR2016 now, about the size of a nickel?

(in the older macs, the PRAM battery ran the clock, in addition to keeping the PRAM values)
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#34188 - 05/11/15 05:27 AM Re: Is there an internal battery in the iMac 5K Retina [Re: Virtual1]
jchuzi Online


Registered: 08/04/09
Loc: New York State
Thanks, V1. I was hoping that you would jump in. Does this mean that, if the battery runs down, there are no real consequences because I have the computer set (via System Preferences > Date & Time to set the date and time automatically?

My G4 and 2007 Mac Pro had problems booting when their batteries died. Replacing the batteries fixed that. I don't want to contemplate that happening with my iMac because it's not user-serviceable.

EDIT: I don't know how long my iMac was sitting in Apple's warehouse before I bought it, especially because it's a refurb unit. I have noticed that, when waking from sleep, the time is wrong but it quickly corrects itself. It may be reading the time that I put it to sleep but I'm not sure. Is it possible that the battery ran down while it was in storage?


Edited by jchuzi (05/11/15 06:05 AM)
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Jon

OS 10.14.2, iMac Retina 5K 27-inch, late 2014, 3.5 GHz Intel Core i5, 1 TB fusion drive, 16 GB RAM, Epson SureColor P600, Photoshop CC, Lightroom CC, MS Office 365

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#34196 - 05/11/15 09:18 AM Re: Is there an internal battery in the iMac 5K Retina [Re: Virtual1]
grelber Offline


Registered: 08/05/09
Loc: North of 49th ||
Originally Posted By: Virtual1
Desktop macs still have a battery though, to maintain the clock when the computer is unplugged from power. ... I think they use a CR2016 now, about the size of a nickel?

Not sure where you got that info; it's not mentioned at all in my iMac's documentation nor does it show up in the iMac's hardware info. Please elaborate.

If there is a battery and it is a CR2016: It's a 3-volt lithium battery which is fairly universal for use in watches and auto key fobs; I've got it in both, and it lasts at least 12 years in my experience.

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#34197 - 05/11/15 09:22 AM Re: Is there an internal battery in the iMac 5K Retina [Re: jchuzi]
Virtual1 Offline


Registered: 08/04/09
Loc: Iowa
Originally Posted By: jchuzi
Thanks, V1. I was hoping that you would jump in. Does this mean that, if the battery runs down, there are no real consequences because I have the computer set (via System Preferences > Date & Time to set the date and time automatically?

EDIT: I don't know how long my iMac was sitting in Apple's warehouse before I bought it, especially because it's a refurb unit. I have noticed that, when waking from sleep, the time is wrong but it quickly corrects itself. It may be reading the time that I put it to sleep but I'm not sure. Is it possible that the battery ran down while it was in storage?


The battery maintains some settings and runs the SMC, as well as powering the clock. When plugged into AC power, the battery is not used. Computers that are unplugged will slowly discharge their SMC battery. I've seen examples of computers that were at people's "summer cabins" where they unplugged all electronics between seasons go through a number of PRAM or SMC batteries as a result.

If the battery is totally drained, the clock isn't updating and the SMC is in a Reset state. When you plug it in, the SMC "boots up", resets the clock the default, and starts it running again. You may have to press the power button twice instead of once to turn the computer on. The clock will eventually update when it connects to the internet, but that may take awhile, and other services may try to start up and use the clock before it gets updated. For example, you may find if Mail auto-launches, it could fail its SSL certificate checks on IMAP mailboxes because "the certificate is not YET valid". Mail often hast to be relaunched after the clock updates to fix that error.

The biggest problem is if the battery is down but not dead. In that case, it may cause the SMC to crash/hang due to low power. It's what watches the power button and turns on the computer when you press the button. So if IT is crashed, you can't turn on the computer. Unplugging the computer from the wall won't reset it, because it'll fall back on the failing battery and continue to be in its crashed state.

So if your SMC battery is low, you will need to familiarize yourself with the SMC rest procedure for your model of mac, as you may need to use it from time to time until the battery no longer will keep the SMC running in any state when AC power is lost. In most cases, the reset procedure for a desktop is to remove AC power, and press/hold the power button for 10 seconds and then release, wait a few sec, and reconnect AC power. (again you may need to press the power button more than once to power it on initially, as the SMC boots up on the first, and turns the computer on at the second)
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#34200 - 05/11/15 09:39 AM Re: Is there an internal battery in the iMac 5K Retina [Re: Virtual1]
alternaut Offline

Moderator

Registered: 08/04/09
Originally Posted By: virtual1
Desktop macs still have a battery though […] I think they use a CR2016 now

The presence of a battery is correct, as shown approx. in the center of this teardown image (source), but it’s a BR2032, not a CR2016. The difference between these two battery models is explained here.
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#34201 - 05/11/15 10:12 AM Re: Is there an internal battery in the iMac 5K Retina [Re: alternaut]
Virtual1 Offline


Registered: 08/04/09
Loc: Iowa
Originally Posted By: alternaut
[quote=virtual1]The presence of a battery is correct, as shown approx. in the center of this teardown image (source), but it’s a BR2032, not a CR2016. The difference between these two battery models is explained here.


I knew it was one or the other. I thought some of the new intels had gone to the 2016 for its thinner profile.
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#34204 - 05/11/15 01:38 PM Re: Is there an internal battery in the iMac 5K Retina [Re: alternaut]
grelber Offline


Registered: 08/05/09
Loc: North of 49th ||
Originally Posted By: alternaut
The presence of a battery is correct, as shown approx. in the center of this teardown image (source), but it’s a BR2032, not a CR2016. The difference between these two battery models is explained here.

You mean a CR2032 (not BR2032), I trust, since that's what is stamped on the battery in the teardown image and is the comparison in the other article, from which it might be deduced that the CR2032 would have twice the life of the CR2016 (ie, even better and longer).

Ancillary query: Are we discussing all iMacs from 2010 to present or just the iMac 5K Retina?
I still can't find any mention of a battery in my Mid-2011 iMac.

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#34211 - 05/11/15 04:00 PM Re: Is there an internal battery in the iMac 5K Retina [Re: grelber]
dkmarsh Offline
Moderator

Registered: 08/04/09

Quote:
You mean a CR2032 (not BR2032), I trust, since that's what is stamped on the battery in the teardown image...

Are we looking at the same image? The image alternaut's link takes me to shows a battery that's unambiguously stamped BR2032.
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#34215 - 05/11/15 06:01 PM Re: Is there an internal battery in the iMac 5K Retina [Re: dkmarsh]
grelber Offline


Registered: 08/05/09
Loc: North of 49th ||
You may be right. At top resolution on my 21.5" iMac (1920 x 1080) the letter before the R doesn't show up well.
The article covering the battery issue, however, refers unambiguously to CR2032. Mayhap BR2032 and CR2032 are interchangeable?

But my lingering question still is: Does the battery issue refer to my Mid-2011 iMac?

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#34220 - 05/11/15 07:36 PM Re: Is there an internal battery in the iMac 5K Retina [Re: grelber]
alternaut Offline

Moderator

Registered: 08/04/09
Originally Posted By: grelber
The article covering the battery issue, however, refers unambiguously to CR2032. Mayhap BR2032 and CR2032 are interchangeable?

But my lingering question still is: Does the battery issue refer to my Mid-2011 iMac?

The CR and BR prefixes refer to different battery chemistry, the 4 digit number indicates the form factor. Note that not all manufacturers carry both compositions, while some may use different prefixes, but this shouldn’t matter all that much to the end user. The motherboard image I provided is that of a retina iMac. You can find comparable teardowns for older iMac models at iFixIt, and yes, the mid 2011 iMacs also have a BR2032 on board.
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#34229 - 05/12/15 05:23 AM Re: Is there an internal battery in the iMac 5K Retina [Re: dkmarsh]
Virtual1 Offline


Registered: 08/04/09
Loc: Iowa
Originally Posted By: dkmarsh
Are we looking at the same image? The image alternaut's link takes me to shows a battery that's unambiguously stamped BR2032.

also, CR2032 is a lot more common than BR2032. same voltage and size, a little different performance (lifetime, capacity) specs
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Moderator:  alternaut, dianne, MacManiac