1986 Ezgo textron 20L4 charger question

[Bluegill]

Hello , new to golf carts , found an 86 ezgo marathon for riding around house and maybe use hunting. The previous owner had told me had bought one new battery , trying to replace 1 at a time. Well when I bought it , I went ahead and bought 5 new batteries, after charging they all read 6.3 volts. My question is should this textron 20L4, shutoff when fully charge. I set timer and it has yet to shutoff and have noticed strong smell of overcharging. It's says it is a semi automatic charger in manual. Thank you and really enjoy reading forum.