Depends on the current
demand will mean little heating
and thus little cooling
High current demand and with inadequate cooling
you can bake a cake over the batteries (just before they explode)
A fan to circulate air will help with cooling.
Do you need it? Don't know.
If you need it will it be enough? Don't know.
An expert could tell you exactly what cooling/spacing/fans you might need if you know the max amp load and list the number of batteries and their type.
I know the basics of how to test... and I tend to opt for more cooling than I need. (I have some batteries in extreme demand service
, but not gel cells)
capacity means more current before things get hot... So just adding more batteries you are cutting the need for cooling.
Look at the spacing of batteries in a golf cart. The spacing is to let the batteries cool under worst case expected conditions. They have a substantial load when there's a couple of "rotund" golfers on board and going up a hill.