Volvo 2006 C70 - Manual (Page 145)

The battery should be disconnected from the vehicle when a battery charger is used directly on the battery.
WARNING!
PROPOSITION 65 WARNING!
Battery posts, terminals, and related accessories contain lead and lead compounds, chemicals known to the state of
California to cause cancer and reproductive harm. Wash hands after handling.
1. More frequently in warm climates.
pg. 163 Maintenance and servicing
Battery
Battery replacement
Switch off the ignition and remove the key.
Unscrew the cover over the battery.
Wait at least 5 minutes after switching off the ignition before disconnecting the battery so that all information in the
vehicle's electrical system can be stored in the control modules.
Remove the cover and unscrew the front side of the battery box using a screwdriver.
Disconnect the battery negative (ground)
Release the clamp holding the battery.
Disconnect the positive cable and lift out the battery.
Install the new battery in the reverse order.
WARNING!
Never expose the battery to open flame or electric spark.
Do not smoke near the battery.