Yamaha G-1 Electric - OK to Convert to Using Three 12 Volt Batteries?

I have a Yamaha G-1 electric and want to run it with 3 each 12 volt batteries instead of 6 each 6 volt batteries to economize. I only travel perhaps 6000 to 9000 feet per day max and charge the cart with a Lester charger nightly. HOW LONG SHOULD A NEW SET OF 12 VOLT NEW BATTERIES LAST? I have been trying this with three each 12 volt, Napa Marine Deep Cycle batteries, Model 8301. The RC rating is 175 on these. They run great at first but after a few months, like 5-6 months only, they seem to suddenly fail. IS THIS NORMAL? IS THERE A BETTER BATTERY I SHOULD USE PERHAPS? OR IS MY 12 VOLT CONCEPT SIMPLY FLAWED?

I am really hoping some one of your fine forum's electrical cart experts an come to the rescue and help me navigate this puzzler! I am stumped!
Many thanks and Aloha,
Bernie of Molokai

Golf Cart Wizard

Cartaholic - V.I.P.
Those batteries are rated 90AH vs ~210AH for 6v golf cart batteries. Should be enough capacity though. It looks like they are combined starting/deep cycle, not true deep cycle however. You may need to get a true deep cycle 12v that is designed for the use case. Or maybe your charger is overcharging. Since the 12v has lower AH and you are using a charger designed for 210 AH batteries it may be charging your lower capacity batteries too quickly. You could try a lower amperage charger.
Very helpful! Several rich avenues of exploration! Thanks so much!

A question: From your experience would you say that what I am trying to do, use three 12 volt batteries in place of the original six 6v, is a common and usually successful practice or a rare and often problematic way of powering a golf cart?

Thanks again and Mahalo,
Bernie of Molokai

Patrick L

Some folks do try to use 3 12v batteries. They will work but not as well as the 6 volters.

Also the type of battery makes the big difference. Simple 'deep-cycle' marine type will not work as well as a 'golf cart' battery. And, not all 'golf cart' batteries are created equal. You really do tend to get what you pay for.
Thanks Patrick. I see that I need to study up on batteries, battery types, and really understand in depth the AH issues to get a solution to my problem. Not quite the simple matter I had imagined. I appreciate your comments.
I'd like to follow up on Golf Cart Wizard's good observations and suggestions about getting a new set of TRUE 12volt deep cycle batteries and also of getting a different, PROPER charger that will charge a the proper, slower rate to match the AH of the new batteries. Can anyone suggest a good brand and model of 12 volt battery to use and a good charger to match them. An "on board" charger would possibly be a help in my situation also.

Many thanks and Aloha,
Bernie of Molokai