battery test says 1/2 good. Should battery be replaced or recharged. Battery is likely 8-10 years old.
I would try to charge it first. After charging recheck the specific gravity. If the test is acceptable have the battery load tested. Most auto parts suppliers will do it for free. The load test simulates the battery starting the engine. You can have a battery that will read good with a hydrometer and still fail the load test.