VERY weird battery not recognized problem - Can ANYONE help? - Page 3
Not sure if this thread is still alive but here is your solution. I have just gone through the same scenario of a new after market battery not being recognised.
Start the laptop with the OLD battery installed.
Upgrade the BIOS. BIOS upgrade V08 is available from Dells support website.
Note: The BIOS will not update with the unrecognised battery installed.
Once the BIOS is updated shutdown and install the NEW battery.
Everything should be fine!