XPS 1330 takes charge from any charger until battery gets below 7%, then only one charger works

I have a Dell XPS m1330 that's about 4 years old now. About a year ago I replaced the battery with a Dell 9 cell battery because the original 6 cell wasn't lasting very long. When I use the computer I usually let the battery run all the way down until it goes to sleep and then I'll plug it in and charge it all the way up again. A few months ago when it died while I was using it I plugged it in with my charger and it wouldn't charge. I tried my portable charger and it wouldn't charge either. Then I tried the charger from my Grandpa's really old D600 and it charged.

Since then I've discovered that if I charge it before it gets down to the critical alarm level (7%) it will charge with either the charger that came with the computer or the portable charger. However if I let it get down to 7% or lower I can no longer get it to take a charge with any charger other than the charger that came with my Grandpa's computer.

Why is this happening? Is there any way I can fix it? Thanks.

Daniel

 

I guess it's a little over 5 years old. I bought the 4 year warranty when I purchased it and then I purchased a 1 year extension on the warranty when the 4 year ran out. After logging on the Dell site it looks like that warranty ran out on 01/29/2013. Really wish I had called about this problem when it first started happening over a month ago.