[Date Prev][Date Next]
[Chronological]
[Thread]
[Top]
Re: [PSUBS-MAILIST] Re: battery pack
Hi Herve,
Interesting point; one not often discussed.
I don't oil compensate my batteries in the NAUTILUS; they are carried
internally. We didn't recharge during use, and flat-out ignored the
possible problem of Hydrogen generation during the proving tests when we
were running Sears Die Hard car batteries back in the Flintstones days. It
did get a little freaky one time when the hatch leaked and brackish water
came close to the batteries; I was really worrying about chlorine gas that
time. They didn't get wet; we lucked out, and we lived and learned.
Now I'm running the sealed OPTIMA batteries; AGM type, in a splash-resistant
box. The batteries work at any angle or attitude, and have a vent plug on
the case. The manufacturer says it won't leak any gas at all during normal
operations or charging. It's there as a safety valve if one overcharges;
then it will burp. Otherwise, you should be able to sleep with the thing in
your bed without any more problems than complaints from the wife. ;-)
They say the structure of the OPTIMA is such that you could shoot a hole
through one cell and still keep running; virtually no leakage due to the
"jelly roll" cell design. Of course, I haven't taken my batteries to the
range lately...
But your point about crush depth is well taken. I'm not really sure exactly
what kind of voids may exist inside the case; but if there's any at all,
we've got a potential implosion problem at some point way down there. (Not
with mine, since they're still inside the hull; but if they were mounted out
in the water, yeah.)
But with what I've seen of the diagrams; and by visually inspecting the
outside of an actual battery, (this is an opinion based on a little
experience taking camera cases and such down underwater) I'd bet these
things would easily withstand recreational SCUBA depths without caving in,
and probably a lot more. Seal the vent with RTV (remove when charging) and
I'd say they were probably suitable for external use on a submarine at
homebuilt-sensible depths.
They're kind of expensive, so I don't really want to use one for an anchor
to see if it pops, but one of these days I might just do that. (Oh, I can
hear the environmentalists screaming now!)
Since these things are sealed, pressure compensation could be difficult.
Solutions? Carry them inside and don't charge during use. Carry them
inside in a vented box that can be pressure purged overboard. Carry them
outside in a pressure pod of their own?
But you've got me wondering. If I get the time (not today) I'll noodle this
one around a bit with the manufacturer, and see what they think.
Pat
----- Original Message -----
From: "Herve" <caribsub@coqui.net>
To: <personal_submersibles@psubs.org>
Sent: Wednesday, June 19, 2002 11:27 AM
Subject: [PSUBS-MAILIST] Re: battery pack
> Pat,
> 4 x 6 = 24 x 6 Volt golf cart batteries, GC15 lead acid with H20
> recombination catalytors for free maintenance and no water refills. Being
> vented they can be pressure compensated
> with oil in battery you still have to refill them with water on a regular
> basis.
> Someone corrects me if i am wrong......
> mostly during recharge and a little bit on load, a battery releases H2 and
> 02 because of the water decomposition in the acid, oil makes the battery
> compressible when diving true but does not prevent the loss of water.
> "Sealed" Gel batteries or AGM batteries, are not exactly completly sealed,
> and are not compressible either because of void spaces inside, they are
> vented out, but not vented in so they would crush under pressure.
> I used to pressure compensate my gel batteries before so they would not
> crush at depth, but it is too much work to do that.
> Herve
> ----- Original Message -----
> From: "Captain Nemo" <vulcania@hawaii.rr.com>
> To: <personal_submersibles@psubs.org>
> Sent: Wednesday, June 19, 2002 4:43 PM
> Subject: Re: [PSUBS-MAILIST] external Motors for depths of 1000ft
>
>
> > Herve,
> >
> > What's your battery pack consist of?
> >
> > Pat
> >
> > ----- Original Message -----
> > From: "Herve" <caribsub@coqui.net>
> > To: <personal_submersibles@psubs.org>
> > Sent: Wednesday, June 19, 2002 10:04 AM
> > Subject: Re: [PSUBS-MAILIST] external Motors for depths of 1000ft
> >
> >
> > > i attache 4 motorguide 107 lbs on my subs, pretty powerfull, i usually
> run
> > > them at 70 %
> > > They are pressure comp, for no deeper than 140 Ft you dont need to
fill
> > them
> > > up with oil.
> > > Herve
> > > ----- Original Message -----
> > > From: "Rob Innes" <innespace@jett.net>
> > > To: <personal_submersibles@psubs.org>
> > > Sent: Wednesday, June 19, 2002 4:03 PM
> > > Subject: Re: [PSUBS-MAILIST] external Motors for depths of 1000ft
> > >
> > >
> > > > Does anyone know how much resistance is caused on the trolling
motors
> by
> > > > filling them with the oil? Approximately how much thrust could
expect
> > to
> > > be
> > > > lost on a Motorguide 107lb thrust unit? Has anyone fitted one or
more
> of
> > > these
> > > > motors to a sub or DPV? I'd be very interested in the results
> > > >
> > > > Rob Innes
> > > >
> > > >
> > > >
> > > >
> > >
> > >
> >
> >
> >
>