Club car battery issues

[Shooter111]

I have 48 volt club car with six new batteries in it. I had not charged the batteries for a couple months since I have a meter and meter was always up in the 50 volt range. The kids would use it every now and then with no problems. So meters starting reading a little lower than usual when running so I went ahead and plugged in charger for a few hours but it barely did anything. Then the next morning I tried plugging in again and charge would kick in and off constantly. I checked each battery and 5 of the 6 are reading 8.1 which seems low for an 8 volt battery. Then 1 of them is reading 7.1. So what is going on is my charger bad or 1 of my batteries bad. Any help would be appreciated.