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Dear Pierre.
When your battery is in the pod the air inside the pod (which includes the
air in the battery also) is pressurized (using a scuba regulator) against the
outside water pressure pushing against your pod.
The air inside your battery and outside around the battery within the pod
is the same pressure because all lead acid batteries (even the so called sealed
ones that don't have cell caps) have small open vent ports that you might not
even see
(sometimes they are just small slits) so the air pressure from within the
pod will enter into your battery thru these vent ports and the interior of your
battery will be the same air pressure as outside the battery.
So since the air pressure inside the battery and outsiide the battery
within the pod is the same there would not be any pressure difference between
the inside or outside of the battery and therefore nothing pushing against
nor pushing out from the battery. It would have no pressure differential
against the battery case which means there
would be nothing pushing either from within nor without the battery.
The pressure would be neutral both within and outside the battery. Pressure
inside and outside the battery exactly the same. So no worries about
cracking
the battery cases.
I think the key here is that you may not have known
that lead acid batteries are actually vented and not completely
sealed so that air can enter into your battery from pressurizing the pod. I
think I understand now that you thought
the lead acid battery was completely sealed and that the pod pressure would
be stronger than the air pressure inside the battery pushing in on the battery
and possibly cracking it, but as I explained that is not the case since the lead
acid
batteries have small open vents in them.
Because of price I will be using 4 lead acid heavy duty deep cycle marine
batteries made for frequent charging and discharging for trolling motors. I
would suggest looking into a better
charger than the average car 12 volt battery charger. You need a more
precise and slightly more expensive charger to get the maximum endurance and
life out of your batteries.
I will either mount a hydrolator in the upper portion of the pod or
else use hydrocaps which screw into and replace the individual cell caps.
Both the hydrolator and hydrocaps convert hydrogen into water. Personally I am
leaning towards
the hydrocaps because they preclude any acid mist from leaking out
from the cell caps and corroding things and evaporating your cell water. The
acid and water and hydrogen mist out
and are contained within the hydrocaps, where the hydrogen is converted
back into water and then everything drips back into the cell without any
mess keeping corrosion down and enabling you to not have to refill your
batteries with distilled water
for a very long time.
Kindest Regards. Bill Akins.
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