How long does a typical car battery lasts when used to power construction power tools?
Obviously it depends on power consumption of particular power tools you use, and how you use them. A typical car battery (70AH) fully charged from the solar panel over weekdays will last me at least a long weekend of work. That will include my typical use of power tools (drill/driver, jig saw, circular saw), as well as reasonable use of indoor and outdoor lights at night. (See separate topical page on small cabin power sources).