I have a question I hope someone can answer, I notice that although my aux battery is wired up that it is still a bit "loose" in the plastic box although the box itself is secured by tie down eye bolts/hooks and ratchet strap.

Can something like bits of rubber or maybe foam be inserted between the battery and the inside walls of the box to keep it steady inside or is the space on the side so the battery can breath/cool etc?

Even if I could only put some in strategic places to stop it moving but not covering all of the sides or ends would help?

Edit:  I remembered I used some foam rubber inside the auxiliary battery box between the battery and inside wall when I had the caravan, so will do the same again, I was just concerned about whether the side had to be ventilated with nothing packed against them.  The box top has vents around the sides and a small one on top.....