what is te TYPE of PRAM-battery in an iMac 21,5 2019

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what is te TYPE of PRAM-battery in an iMac 21,5 2019

I am in the process of investigating an upgrade for an iMac 21,5 2019, new SSD, 32 GB ram.

On iFixit they provide excellent teardown of the iMac but fail to be specific on one detail: the PRAM battery.

It is mentioned you need a BR1632 or a CR1632 or a …2032

Whilst the power does differ, it is all in the same range. The differences are the sizes (the numbers) and the 'CR' or 'BR' has to do with temperature-resistance where CR can handle 70 °C and the latter can handle up to 80°C.

The sizes may be a problem: the first 2 digits are the diameter in mm and the last two are the thickness, being that 32 is 3,2 mm

Now the Q:

which type will I need?

I would guess the BR or CR is not much of a deal, but het size will be. It is sort of inaccessible in an iMac, so It seems a good idea to get it right the first time.

Also, a good idea to know in advance, so I can order the right stuff.

iMac (2017 – 2020)

Posted on Dec 9, 2024 4:51 PM

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Answer 1

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John Galt

Level 10

156,326 points

Dec 10, 2024 4:48 AM in response to Jo!

Either one will work but BR is more appropriate for the low power application required for backup memory.

CR is more appropriate for higher power requirements.

For the Mac, BR will last longer. If you want to get it right the first time use the BR2032.

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Answer 2

Jo! Author

Level 1

95 points

Dec 22, 2024 1:11 PM in response to Jo!

well, found out the hard way: it is a BR 1632 originally installed.

If I want to replace it (currently 2,83 V) I will have to wait till the shops are open.

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Answer 3

Allan Jones

Level 9

78,860 points

Dec 9, 2024 5:45 PM in response to Jo!

Per the service manual posted on the site you found, it is a BR2032.

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Answer 4

Jo! Author

Level 1

95 points

Dec 22, 2024 1:09 PM in response to Allan Jones

well, SURPRISE! (not funny): it is a BR1632

it should show 3+ volt but does only 2,83 V.

I am in doubt: is this enough volts or should I wait till the shops are open …

I thought it would be flexible in the mounting, but it appears not flexible at all: the socket/holder is just the width of the battery with is 16 mm …

BUMMER.

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Answer 5

John Galt

Level 10

156,326 points

Dec 22, 2024 1:46 PM in response to Jo!

I took your word for the site you referenced regarding its size. Of course I should have verified that for myself and only fixated on BR vs. CR.

You can take your time finding the BR1632. The 3 V you cite is nominal. A brand new BR1632 will measure less than that — less than its CR equivalent. 2.83 V is perfectly normal and will probably remain that way for years.

If you bought a CR2032 save it for an AirTag. The reason for the CR is that an AirTag's power draw is greater, so it's more appropriate for the application. They typically last about a year in service, vs. a decade or more in an iMac (assuming you don't unplug it routinely — don't do that).

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Answer 6

Dec 9, 2024 5:47 PM in response to Jo!

Either of these batteries – 1632 and 2032 –is available at your local grocery store. I suggest you buy one of each and simply return the one you don't use.

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