Volvo 2008 V70 Owner's Manual page 225

Maintenance
Regularly check that the electrolyte level is correct and never fill above the level mark.
Check all cells. Use a large screwdriver or a coin to remove the cell caps. Each cell has its own maximum and
minimum level mark.
If necessary, top up with distilled water to the battery's maximum mark.
Tighten the cell caps thoroughly.
CAUTION
Always use distilled or deionized water (battery water).
Never fill above the level mark in the cell.
Changing