In the basement I have over 1 dozen car and mower batteries on the cement floor along a wall. I need to test them to see which ones are good, bad or chargeable. I have an automatic charger and an electronic voltage tester. Should I just test each one as they sit or charge first or? Some have been in storage for over 5 years. Where they sit on the floor is on one side of the landing of the stairs. On the opposite side of the stairs on this same basement floor are the water heaters which were new about 3-5 years ago. I'm concerned about vapors creeping over to the pilots on the water heaters. Maybe I could have a fan blowing on the batteries as they charge to dissapate the vapors?