here are just a few things I would suspect.
First is that you are not getting good fresh batteries, were they individually packaged and is there a date on them, try getting them from a different source to make sure you are getting different lot and try different brand.

Look at the contacts on pc for the battery look for signs of oxidation. Look at the soldering to see if it looks damaged or bad, they can crack or break. Some one with a tester could check them to see if they are good.

Could be a leaky capacitor on the motherboard.
Of course make sure you are connecting the battery with the correct polarity.

When you are taking out the cmos are you just immediately putting the new one in and then restarting? If so do this instead, unplug from power, remove cmos battery, leave it just like that for at least 30 mins. This allows a good power cycling. Then replace with good new battery (you can have the battery tested for strength) if battery has date codes you can check for freshness, you want to try to get a fresh one, after install of battery, plug in and try it.
Sometimes a minimum 30 min power cycling resets things.

Those are a few things to look at for now.

I find it hard to believe this is a CMOS battery problem. Those batteries normally last for years, most last as long as the computer they are installed in. Have you tried replacing the same battery at all during these problematic startups?

What or who prompted you to start removing all these items each time you shut the computer down? Have you tried removing only one at a time trying to isolate the issue?

As you seem unafriad of your computer could you remove the left side and tell us the make and model of the power supply please. Also when you are booting up boot into the BIOS and check the settings. One of those windows in the BIOS will display all the voltages at spec and the actual voltage. There should not be more than a 10% difference above or below. I suspect your "system low voltage" is referring to a doubtful power supply rather than your CMOS battery, or too much connected to the power supply. Do not change anything in here and exit without saving to be sure.

Are you saying that at some point you reformatted and installed a non Dell version of XP? If so there is no warranty right? Below I have added a link to a power supply calculator so you can check all your components and see if you are over extending the current power supply.

You say you have a RAID array installed which is probably non Dell. What else is installed and how much "stuff" is connected to the USB ports but is not self powered?

Here is a link that might be useful: Power supply calculator

Thank you for responding.
Power supply make: Dell (celetronix?) model: cx305n-00
USB plug-ins w/o own electric - keyboard, mouse, occasional camera and ipod
USB plug-ins w/ an electric plug: printer, external hard drive, speakers.
Monitor has own power obviously.
Other stuff w/o own power- 1 card reader, 2 dvd drives, video card, 2 memory cards, fan, sound card, 2 hard drives.

The error message regarding the power supply only appeared 2 times about a week apart before this all happened. If I do a restart, there is no error message any more.
I did not reformat! At one point, I was not able to start windows and they wanted me to reformat. But really, the memory card just wasn't in right from all my unplugging and replugging. Fortunately, I always hang up when they want to reformat! Lol! In the meantime, I had them help me disable the RAID to save things that weren't backed up. I have since backed up. Phew!
Also whether this is of note or not, the two USB plugs in front of the computer are unusable as both stripped the USB cables of their pins. They are stuck in there and I can't use them. If I try, the system could reboot but mostly just doesn't see what I plugged in. I told Dell of this and they said that they are attached to the motherboard and that to replace them, I would have to replace the motherboard so I left it. It has been that way about a year. Next time it goes down, I might try to remove them with some needle nose pliers.

I have tried two different brands of batteries with the same result. I have tried to reuse the batteries and they do seem to be drained. This has to take place while the computer is off for a period of time. I can do a restart once the computer is on. Batteries were in single or double packs. I didn't notice any corrosion. Everything is shiny. But really, I might need to get glasses or a magnifying glass to see something like that. The battery is CR2032 - 3 volts.

I have been reinstalling the battery immediately as I read somewhere that there could be a memory problem with the bios if I left it out for a period of time so I never tried 30 minutes. That I would only do with Dell on the phone because of my warranty. Maybe they will try that next?
All components, including the raid system, came with the computer. It is still under warranty for a couple more years.
Dell had me take off one item at a time and restart with each item unplugged. They also had me plug into the wall which makes it sometimes work when other things fail. I have replaced the surge protector but I still have to plug the CPU into the wall, at least when it first jump starts. It has been getting progressively worse as far as how many items need to be unplugged before it comes back. Replacing the battery was my idea and it works. I have been leaving the computer on all the time and want to finish some year end bookkeeping stuff before I risk turning off again. But soon I will have to call Dell back and I don't want to go through the dance again, only to be down again and maybe next time not be able to get back up at all. Nor do I feel 100% comfortable playing with all the wires while the computer is plugged in. Though I'm careful, I've seen a couple of sparks already and some plug-ins are cramped.

But after that long winded post, what would cause the cmos battery to lose power while the computer is off, if that is what is happening? It has to be some kind of power leak?

wow is about all I can say, personally if the pc was mine and I had done that dance more than a couple times with a pc that was still under warranty, I would be telling them to send a Dell chosen repair person to my home to fix the darn thing, ok I might use different language LOL.

seriously that is just nuts for them to expect you to do that routinely. Sparks and the inside of a pc is definitely not a good thing, they are asking you to put your self at risk touching electrical components with the power on.
I would demand a repair or better yet replacement, that had to be a pretty expensive pc they need to pony up and make it right.

Have you tried just for the heck of it in your dance getting an extension cord and plugging it into another outlet that you absolutely know is on a different house circuit? I know that is one of the things tech support makes you do and sometimes it can provide an answer.

I would just tell them to fix it or replace it.

I did a little google searching on this and strange thing is every one that I ran into that mentioned having cmos batteries having to be replaced often were all Dell.

Well if the machine is still under warranty I agree with ravencajun, you need to get serious with Dell and demand something better than the treatment you have received so far. Hopefully you have documented each contact with Dell. Next time ask to be passed up to a supervisor and have them review the situation. As far as I can understand all service calls are recorded as are the suggestions the tech offer to fix any given problem.

Perhaps those pins stuck in the front USB ports are the issue by short circuiting.

I was wondering that those pins might be short circuiting it too but they have been like that for a year or so.
I've tried other outlets but not on another circuit.

OK, I agree with you all then. It is time to insist. I do have patience but I can't think of anything else. The problem with this is you have to wait a period of time with the computer off to see if any fix worked or not.

It will take me a while to turn off the computer again - I need to make sure some work goes out but I will report back with the results. I've never had problems with Dell replacing parts before so I'm not expecting any in the end this time either. I'm not looking forward to a possible replacement of the motherboard though. Maybe some obscure fix will cross my path...

Thank you all for your help.

Good comentaries, am actually facing the same problem right now.
I turn on my pc and when booting, it hangs in between while loading windows (XP) but before it gets here it brings that 'low voltage CMOS battery'. How do i go about with this? I tried twice fixing in new batterires but they all give the same message of CMOS low voltage battery and yet these are new batteries

Here is a link that might be useful: www.yahoo.com

Kasadha,
In the end, Dell replaced my power supply and that seemed to work.

Eventually the fan went crazy and only ran fast. They replaced the motherboard and the fan and it still ran fast and noisy. They did send me a new computer. I didn't have to ask.