I messed this up last time and somehow = deleted my message, so here goes for one more try. I am trying to fix my = auxillary battery system on my '81 Westy. I was wondering if after = installing an isolator, I could install a deep cell battery for my aux. battery and = still have a regular car battery for ignition (can they be different sizes)? = Also, since a deep cell won't fit in the compartment below the driver seat, = would I have any ventilation problems (how much ventilation does a battery need) = if I had the deep cell hooked up in the cupboard behind the drivers seat = below the sink/stove?