We get a lot of interesting email from readers, and occasionally there’s one that points out something that other readers might not know about. In this case, a reader asked “I have a iMac running 10.13.6 and some how when I start my Mac it tells me that my date and time is incorrect, but it’s not so I was wondering would you be able to explain to me in a easy way that I can understand: what’s going on?” Read on for the answer!
Internal Clocks and NTP
The most likely culprit is a dead PRAM battery on the motherboard of an older Mac. Your Mac always checks the time when it connects to the internet, through what’s called an NTP (Network Time Protocol) server. When the Mac is set up, you supply it with your time zone (and it can also determine your location through Wi-Fi positioning), and it knows that the computer is currently at a certain offset from Coordinated Universal Time (UTC) – for example, here at AWT HQ in Colorado, we’re in the Mountain Time Zone, which is set to UTC – 7, or seven hours behind UTC, the time at Greenwich, England.
As you can see in the screenshot at the top of this post, Macs are set to check the time through an Apple NTP server (time.apple.com).
Older Macs also used an internal battery (usually a CR-2032) to retain PRAM (parameter random access memory) settings and keep a clock running. When the Mac starts up and sees a discrepancy between the internal time and what NTP is showing, you’ll get an error message.
It might appear that the date and time on the computer are correct, but even a slight discrepancy on the order of a few seconds causes the error message to be displayed.
Which Macs Use Backup Batteries?
The following Macs have CR-2032 or BR-2032 backup batteries that may need to be replaced from time to time:
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Mac mini (Late 2005 through Late 2012)
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Mac Pro (Early 2008 through Mid 2010)
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Power Mac G5 (Late 2005)
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iMac G5 (2004 – 2005)
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iMac (Early 2006 through Mid 2011)
Earlier Power Macs, iMacs, eMacs, Mac Quadra and Mac Centris models used an ER14250 3.6V PRAM battery.
Where to Find Batteries and Installation Instructions
If your Mac is older and is displaying the error message, then it’s probably a good indication that the PRAM battery needs to be replaced. CR-2032 batteries are very common; most stores that sell batteries will have CR-2032s on hand. The BR-2032 is a high-temperature model of the CR-2032 and is recommended for specific models of Macs that run a bit hotter.
One place that can tell you what type of battery you need, sell you the battery, and also provide installation instructions is OWC, found online at MacSales.com. While some older Macs are quite easy to take apart for battery replacement, others should only be repaired by experienced hobbyists or technicians.
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