Remove the battery from the motherboard and install some jumper type pins in its place. Solder or make a "plug in" type of connection for wires. Run the wires to the new battery and mount it somewhere off of the motherboard. That's what I did.
The clock in my A4000T (converted from a desktop machine) loses 9 seconds every 15 minutes. So, I also use FACTS to keep it on track. No idea why it does that losing time thing.
