What is proper way to disconnect old batteries and connect new batteries? how long should I let new batteries charge before using? My wife, grandkids and myself use electric cart at campground we attend.
Hi, Bob! You mean, does it matter which battery you disconnect first, for safety's sake? Not that I'm aware of. Once you break the circuit, you've reduced the voltage from the collective voltage of the whole pack down to 8 volts, not enough juice to sizzle a squirrel.
My concern would be with the slosh factor. Those batteries have acid in them, and caps can get loose as they bounce around in a golf cart. As you pull them out of the cart, mind your clothes, wear goggles, that sort of thing.
Connect the new batteries exactly the same pattern the old ones came out. Batteries wired in series give you an entirely different battery pack than the same batteries wired in parallel. Here's an article I wrote on wiring up your batteries if you're unfamiliar with this stuff.
On charging: The new batteries should be near fully charged when you install them, because that's how they are stored and sold (hopefully), but I think I'd let them charge overnight on a smart charger anyway before I ran them.