Re: I got an idea, Lets talk about subs now.

[Dick Morrisson <rmorrisson@unidial.com>]

Alec,
When you refer to "sealed" batteries, do you mean "gel cells"?  I ask because
AGM batteries are also sealed but supposedly do not out gas enough to be
concerned about.  Also, here's a little food for thought.  What if one were to
keep the batteries in a separate pressure container that was purged with Argon
before a dive and again before taking the batteries out (or opening) to
recharge?  This would eliminate the explosive mixture potential (not enough
oxygen) in each case, would it not?  The container could handle the small
increase in pressure from the out gassing during use and then relieve itself (no
pun intended) when purged the second time.  This way, normal (cheap) batteries
could be used.  Any thoughts from the experienced or knowledgeable members?
Dick Morrisson

asmyth wrote:

> I went through the archives and found that the same exact question regarding
> battery squeeze was posted many months ago. Ken Martindale provided a great
> answer, which I'll try to summarize (or butcher?)
>
> - According to manufacturer's specs, sealed batteries are good only to 3-4
> atm
> - Oil-filled conventional batteries should not be inverted (the oil floats
> up and contaminates the plates)
> - Open-cell batteries with caps still spill if inverted.
>
> Still, some methods come to mind that could conceivably work. Of course they
> all would require some experimentation to make sure.
>
> 1) Drill a small hole in the top of a sealed battery. If the electrolyte is
> indeed immobilized, it should not leak out. The batteries would have to be
> in a separate compartment with NO switches, motors, etc. because there could
> be some H2 around. Catylators would presumably not work on an "un-sealed"
> battery because it would have no use for their reconstituted water, hence
> the isolated compartment.
>
> 2) Use oil-filling ON A GEL BATTERY. Maybe in a gel (as opposed to liquid)
> the oil would not float up and contaminate the plates.
>
> 3) Use a conventional battery, but fill the air spaces above the cells
> completely with electrolite. Only problem is, you'd have to drain some out
> before every charge, otherwise the electrolite would over-expand due to the
> creation of bubbles. Its not only messy, its a hassle.
>
> Options 2 and 3 sound very messy. Busby's book in particular has some very
> negative comments about oil-filling ("a review of the literature makes one
> wonder that the system works at all", "messy, generally difficult to
> maintain", "destined to get salt water in them at one time or another").
>
> So for now, I am still leaning towards drilling little holes. Please, any
> other ideas? I hate to ruin a good, $138 battery. If anyone has a SPENT gel
> or AGM battery, you could contribute to the knowledge of humankind by
> drilling a hole in the top and leaving it upside-down!!!
>
> -Alec
> PS: From the length of this message, you may deduce that the motor on my
> milling machine burned out so I can't do anything in the garage tonight!
>
> > -----Original Message-----
> > From: owner-personal_submersibles@psubs.org
> > [mailto:owner-personal_submersibles@psubs.org]On Behalf Of Jonathan
> > Shawl
> > What about the sealed battery question posted by another member?
> > I think he is still waiting for an answer if anybody has one.