I have posted to the Dell Forum but haven't gotten a response. HOPEFULLY someone can help me.

Facts:
1. I have a Dell Latitude D810 (purchased 2/2007 no longer under warranty)
2. Needed a new Battery - purchased 12/08
3. Battery slowly quite keeping its charge. It stayed charged some days for an hour and others for only 20 minutes or less.
4. Ordered a replacement battery while still under the ONE year warranty.
5. Received new battery and it only kept a charge for about 5 seconds.
6. I thought I got a bad battery so asked for a replacement.
7. New Battery states it is "not present".
8. Running Windows XP

It has been suggested that Dell update or replace my BIOS. Dell sent me a link to do this but it won't work unless I have a battery installed. Since my battery is "not present". This is not an option.

Now it SEEMS as if I need to repair the motherboard. I was wondering if there is anything that I can do to correct this problem. Or to fix the motherboard myself. I am computer illiterate, but am pretty good at figuring out things if given step by step directions.

Someone replied on another forum that I may want to check my CMOS battery. I don't think this is the problem because everything else works just fine as long as I am using my A/C Adapter. (I purchased a new one about 6 months ago)

Any help will be greatly appreciated
You would need a diagram of the Motherboard. Or else fabricate your own battery charger. Do you still have the old AC adapter? Did it really go bad?
If the laptop is FAILING, it can draw more current and can not charge the battery. And if the battery is charged, it will not give long service.

Building a home made battery charger for the kind of batteries use in laptops presents some risk. The charging current is on the order of about 500 MA for about 4 hours, but this can vary a lot, depending on the battery type.
The laptop itself has circuitry that regulates the charge rate. This may not be on the motherboard. It may have burnt out. Without a diagram of the motherboard and the other things inside the case, it is just a wild guess as to how to charge the battery. The only thing I would try is to charge the battery outside the case in a home made circuit that limits the current to 500MA and max of 12 volts. And do it in a safe place. it could explode.

Come to think of it, I would not do that. I have an old lap top that works good on AC. I tried to find an battery for it, tore it open, and was dismayed by the complexity of the thing. I just use it a a small AC powered computer.

If you really like that laptop, just WAIT. Someday somebody will have a good one for sale and you can buy it. Then you will have two. One to travel, one to keep at home.