Here at work we have a golf course fleet of ~20 carts. The 2008 models came with the 'single point watering system'. After having several batteries go bad in the first two years, and finding the cells empty..

We went back to watering the cells individually. We have not ordered carts with that option again. Battery life went back to 4 years, which is our fleet exchange rate.
And on the subject of filling batteries..
Using the 'automatic' shut off filler like the picture above tended to overfill the cells, and cause residents to complain of leakage staining their garage floor.
Back to basics - use a funnel and bottle to fill. Doesn't take THAT long.