I'm not sure about the 26K model, but there is room in the 34E for four six volt golf cart batteries. 6V batteries take less space, but they are taller.
There is plenty of vertical clearance, and the four golf cart batteries fit like a glove, (someone must have actually considered it when they designed the steel shelf that they rest on).
You will very likely want to get a Flow-Rite battery water level system for each pair of batteries, because with the cables installed there is NO room for normal maintenance without removing the batteries each time.
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