I was thinking of a different chart for 8 volt battery (golf cart), if it shows bad or weak for the group you still have to test each one separately. I think I paid 25$ for my 100 amp tester. Do not use often but is great tool when you start having problems. Especially when the in-laws/out-laws state, "The battery looks brand new", it is called Preventive Maintenance. LOVE IT. LOL!!!!!!!!!!!!!