Alert! system battery voltage low on dell optiplex gx620 xp

hi i dont know if i have the right forum here but im shure someone can help.
about a week ago i brought a dell opitplex gx620 ussf off ebay and i know it was never going to be absolutley perfect but anyway i when i turn it on i get a message 'Alert the system battery voltage is low' and i had to enter the date and time every time i turn it on.
i read up on forums and found out the internal battery needed replacing so i got one and the date and time issue went.
however i still get the low battery voltage message every time and dont know what to do about it.
any help would be grateful

 

if you have not set a memory on the battery it will never hold a charge, instructions say charge battery, run completely down and recharge 3 times before memory will be set.

if the charger is old it will not charge properly either.

Dell chargers do not last a long time.

Also do not leave battery in while running on ac power or this will ruin battery.

 

This is a desktop, he is talking about the CR2032 battery on the motherboard. A non rechargable watch battery that gives power to the little chip that holds the time and motherboard settings.

That battery is user replaceable and doesn't need anything except long finger nails to pop it from the socket. They are available at the dollar store for 2/$1.00 .. Its called a CR2032 or something like that, if you pop it out it will be printed on the face, the slimer one is a CR2025.

http://www.microbatteryshop.com/PBSCProduct.asp?ItmID=11707583