You could do that. I looked at the MTS web site. They make the individual vent components, so you could add another outside vent (one for each 6-volt battery). But they do not apparently make the part that the vent hose would attach to on top of the battery. Perhaps you could make up something out of PVC from Home Depot. And if you could figure a way to join 2 vent hoses into a Y configuration, you could use your existing single vent on the outside of your fiver, otherwise you'd need to add another vent outlet.
