how do you change golf cart battieries and how much does it cost?

Golf cart batteries are deep discharge, marine style batteries. They cost about double that of standard automobile batteries, so expect to pay in the neighborhood of $150 per unit. They come slightly cheaper and significantly more expensive. Did a quick search and found prices ranging from ~$100 to $400 per battery. I think they're mainly 6 volt batteries, rather than the 12V units found in automobiles. They are changed out by using a wrench top loosen the terminals, much the same as one would find in an automobile, then lifting the unit(s) out of the chassis (often found under the seat). Replacement is a reversal of the removal instructions. They often come in groups of four to six units per cart. I saw one avert after reading your question for a set of six batteries for "only" $1200...le cough, le splutter.

Golf cart batteries are that. 6 volt batteries are around $66.00 per! Trojan batteries are the best all round battery hands down! You need to charge them as a pack with a 36 or 48 volt charger. You can use a 12 volt charger but it will take awhile to do so.

If you want to change them, you will need to go to a specialised battery shop If you want to charge them, just use a 12V AC to DC converter, the one you plug into the wall Make sure you attack the anode to the anode (red to red black to black)