You won't be sealing flood lead acid batteries in a capsize
and venting them properly. If you use AGM
batteries than all you need to do is just secure them as that is the only thing they do require other than proper charging
. AGM's are the best for boating
. I switched to them ii the prior boat and loved them but have not switched yet in the new boat as the whole charging
system will require replacement. The charging system has to be set properly for one or the other else it's money
Flood batteries will out gas and that will include Sulfur Dioxide as well as Hydrogen Sulfide. Pure hydrogen also is possible. The out gas is a corrosive mixture and is what needs venting else any non Nobel metals will show signs of corrosion
. On the last boat the PO put the A/C unit in the same compartment. The aluminum heat exchanger
was corroding when I got the boat. Not fatal but could have headed in that direction.
The battery box
is more for the overflow that can happen when the batteries boil from poor charging. Not that it is normal to happen but because it could happen even on a proper boat should you not monitor
the water levels in the cells. You want to contain the spill no matter what.
In the case of a capsize
your electrical system
has but a short lifespan. The salt water
and the electricity will quickly destroy anything with current
in it. Putting batteries inside something won't help all of that much. The bigger danger
is that they come loose and a 70 lb battery flying loose could put some nice sized dents in your skull. In a capsize you would expect all heck to break loose and violent motions can make deadly weapons of even small objects. A battery could smash through a bulkhead with enough force launching it.