Upload & Sell: On
Your charger will show you the status of the batteries, and which ones are going bad.
See page 27 and 28 of your manual
Page 27 is power switch (on/off) and page 28 is the shutter button.
Are you sure you are looking at a 1D Mark II or 1Ds Mark II instruction manual??
I don't see anything in the manual on how to check the capacity status of the batteries, other than advice to fully discharge before recharging to avoid reduced capacity.