Re: [PSUBS-MAILIST] Re: battery pack

[Doc <doc@bionicdolphin.com>]

Aloha Pat,

 I've been using the Optima batteries for years and have had them down to 150'
without a pressurized housing with no problems at all. As a matter of fact my
Optima's are 7 years old and still going strong!
In my humble opinion, they're well worth the extra price.

Doc

Captain Nemo wrote:

> 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
> > > > >
> > > > >
> > > > >
> > > > >
> > > >
> > > >
> > >
> > >
> > >
> >