When i power my iMac off & restart later i have to reset the time & date from the default date & time the machine only keeps the time while the mains power is on.
iMac 27, retina 5k 2019, 3.7 Ghz 6 core Intel i5.
Radeon Pro 580X 8 Gb.
32 Gb DDR4 2667 Mhz RAM.
Sonoma 14.1
Please advise.
iMac (2017 – 2020)
It does not appear you have a battery issue.
The MacTracker database shows the last iMac 27" to have an internal backup battery (Apple's term) was the Mid 2010 model. The last 21.5"iMac with that battery was the Mid-2011. It is possible the change was to make the newer iMac sealed-case form factor possible. Changing internal batteries is no longer an at-home job.
This is confirmed by a popular self-service site that I'm not allowed to link, and by the compatibility chart for the CR2032 battery on the OWC site:
3V NewerTech Lithium CR2032 coin battery- Computer PRAM Clock Battery & also for Apple Remote
Newer systems often use a capacitance system. The batteries were never intended for long-term runtimes. They were intended for short periods off wall power such as for moving or maintenance. The capacitance systems, if that is what is used, have similar limitations.
If you want to unplug your computer every night, resetting the clock will be one of your morning routines.
Why are you switching off the mains?
The best practice is to Shut Down from the Apple Menu and then Startup using the Power Button.
If the iMac is on a switched Main, leave the switch on or move it to an unstitched main.
I'm fairly certain I saw a CMOS battery in both a 2017 & 2019 iMac 27". I have not worked on anything older for quite some time. The battery is now located on the backside of the MLB near the top next to the WiFi card.
Don't you have your Mac to automatically set the time in settings?
Time & Date not kept when machine turned off, can it be the cmos battery?
