Batteries should be recharged when they are at 75 –50% of their capacity.
Wet cell batteries lose 1% of their charge per day, so after 30 days she's down to 70% if the card has not been driven. It's easy to see how she could be drawing the pack down to low between recharging. This is considered a deep discharge and it will shorten the number of times the pack can be recharged.
The best thing she could do is to get somebody to put a digital voltmeter on the cart so that she could know exactly when it needs recharging. And in dash digital voltmeter will help her extend the life of her new batteries
PS
Remember to check the water levels once a month.