Probably too late now for you (April ’18) but I would take the vehicle battery out (optional), wash it with warm water and a little soap, clean the terminals, check and fill the electrolyte levels, charge it with a battery charger for at least 24 hours and then test it with a hydrometer. A further test is to take it to an auto parts store after it is charged and have them load test it (for free). This will help you determine whether you need a new battery or not.