This is a fun one SOLVED?

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Dell T4330, loses bios settings when power is lost. So i go and replace the cmos battery. I plug it back in and it will not start.
I get the little display and a blue light on the front for a few seconds, hit power button and get nothing . I figure maybe the new (harbor freight) cr2032 battery is bad, and replace it with an energizer cr2032. Same problem.
I then reinstalled the original battery and it starts up (bios was reset obviously). I remove the cmos battery, and leave the cmos socket empty, and it fires up.
Put in one of the new batteries, back to not powering up.
Put in the old battery, and it fires up. I have no idea why this is this way.
Entering Idrac (Dells version of ipmi ) says that battery is good, but it cant be if bios is reset to defaults on power loss.

Edit:
I tested both batteries with a DVOM and they both have ~3.2 volts.

Edit 2:
I swapped the cmos battery while the system was powered off but plugged in (i dislike doing this) , and it boots.
ill do a bit more testing and report back

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Ok , this is strange.
I left it unplugged and went to get a drink, returned and it started normally and remembered my bios settings.
I guess you need to change the cmos battery when its off, but plugged in. Perhaps some anti-tamper routine is at work?
I dunno but its working now lol.

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In my experience with Dell’s Enterprise level stuff, there is always some weird witchcraft involved when doing simple things that have no rhyme or reason.

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I’ve experienced something similar, don’t know the technical reasons but could isolate the pattern:

  • The term CR2032 just specifies the battery’s physical dimensions (20mm diameter, 3.2mm height)

  • Many new CR2032 batteries have a voltage of 3.3V.

  • Changed an absoluetely dead battery on an older motherboard with such a 3.3V battery: Similar odd behavior as described in your initial post.

  • Then checked the CR2032 battery of another new motherboard (less than six months since date of manufacturing) and its battery had 3.0V.

  • Then took that 3.0V CR2032 battery to the problematic older motherboard and it worked fine again (to this day, years later).

Why?

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