As a longtime tech writer, I’m sometimes asked how I get ideas for articles. Some of them come from readers who ask questions that intrigue me. The other day, an email arrived asking “I have an iMac running 10.13.6 and somehow 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 an easy way that I can understand: what’s going on?”
Here’s what the problem is, along with a solution.
Internal Clocks and NTP
The most likely culprit is a dead PRAM battery on the motherboard of an older Mac. Macs always check the time when they connect 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 – the current time at the Prime Meridian in Greenwich, England).
The screenshot at the top of this post shows that Macs are set to check the time through an Apple NTP server (time.apple.com).
Older Macs used an internal battery (usually a CR-2032) to retain PRAM (parameter random access memory) settings and keep an internal clock running. If the Mac starts up and sees a discrepancy between the internal time and NTP time, you’ll see 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 (see image at right) that may need to be replaced from time to time:
- Mac mini (Late 2005 through Late 2012)
- Mac Pro (Early 2008 through Mid 2010)
- Power Mac G5 (Late 2005)
- iMac G5 (2004 – 2005)
- iMac (Early 2006 through Mid 2011)
Earlier Power Macs, iMacs, eMacs, Mac Quadra, and Mac Centris models use an ER14250 3.6V PRAM battery.
OWC to the Rescue!
If your older Mac 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 have CR-2032s in stock. 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.
Fortunately, OWC can tell you what type of battery you need, sell you the battery, and provide installation instructions. While some older Macs are quite easy to take apart for battery replacement, others should only be repaired by experienced hobbyists or technicians.
With a fresh PRAM battery – and assuming that no other hardware issues arise – your vintage Mac may remain useful for years to come.