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Re: [PSUBS-MAILIST] Battery question
Hello psubbers.
Long time since my last input to this group, but I find this OSS project interesting and maybe the battery solution, ( and maybe some other components too ?), for my project is also valid for this project.
I suggest to house the batteries inside the pressure vessel. There are many good reasons for this desicion.
Pressure housings are expensive to produce and a marginal increase of the main pressure vessel diameter can handle also the batteries.
Standard box type batteries will give very poor "filling", volume vice of "small" sylindrical battery pod pressure vessels. Battery technology is rapidly improving in these "green electric car" times and it is easy and cheap to re-arrange internal battery racks instead of producing probably new battery pressure vessels when cheaper, smaller and higher power density cells are available.
By having the batteries internally the heavy amp cable penetrators are also not needed.
Gel type lead batteries ala OPTIMA will not gas during charging or discharging and can be stored and operated in any direction.
This is my choice so far.
My project has a 1400mm internal diameter main pressure vessel. On my wooden full scale mock-up I have "good" space for two people sitting besides on top of the batteries and the "hard" internal ballast tanks.
Best Regards Finn Limseth
----- Original Message -----
From: "Jeff Post" <jeffpost@rawbw.com>
To: <personal_submersibles@psubs.org>
Sent: Wednesday, January 29, 2003 9:29 PM
Subject: RE: [PSUBS-MAILIST] Battery question
> Upon inspection, it seems that no one wants us to be able to compare batteries
> online. I looked at the major battery manufactures, and at the common online
> boating stores. No one wants to give you the same stats for two different types
> of batteries.
>
> So, here is a composite view of flooded verses AGM batteries. I tried to use the
> type 27T battery style as a standard for comparison. It seems that AGM batteries
> are at least 2 times more expensive. Flooded are approximately $100 ea. AGM were
> $200 and up. Flooded batteries of this type were rated at approxiamately 105 AH
> using the 20 hour method. AGM's were 88 AH, although I can't be sure of the test
> method.
>
> Let's make some assumptions:
>
> 2 motors @ 40 amps X 5 hours running time = 400 AH
> life support and electronics 10 amps X 72 hrs (you do want to be
> rescued,right?)= 720 AH
>
> Fudge factor for incomlete charging or battery aging .75
>
>
> Equals 14 X $100 for flooded batteries = $1400
> or 17 X $200 for AGM batteries = $3400
>
> Maybe Dan could give us an idea of what he spent to purchase steel for his K350.
> That figure along with the battery cost could give everyone an idea if this
> realistically can be done on the proposed budget.
>
> Jeff
>
>
>
> Quoting Warrend Greenway <dub@linuxmail.org>:
>
> > Wrong, good sir. Those decision won't be made at all without quite a
> > bit
> > more consideration. I'm asking for all the information on battery
> > choices
> > from all the "info guys", and anyone else with info. Cost is a prime
> > consideration. Got any info or practical experience? Gimme.:)
> >
> > Warren.
> >
> > > There may be other considerations that should be examined. What about
> > energy
> > > storage density differences between the two batteries? What are the
> > amp/hour
> > > differences, and what are the displacements of the two choices? Also,
> > I don't
> > > think the cost factors were examined very carefully. I believe that
> > AGM
> > > batteries are about 3 times more expensive ( metric conversion = 3
> > times more
> > > expensive :) ). It seems that decisions are being made without much
> > consideration.
> > >
> > > Jeff
> > >
> > >
> > >
> > > Quoting Warrend Greenway <dub@linuxmail.org>:
> > >
> > > > Sounds good. I'll just wait a bit before making a decision, then!
> > > > :)
> > > >
> > > > Warren.
> > > >
> > > > > Solo has AGMs inside the pressure hull. One of the more bizarre
> > design
> > > > details is they're mounted on the "ceiling" instead of the floor.
> > This
> > > > is to raise the center of gravity, since its a flyer and I'm trying
> > to
> > > > reduce the self-righting moment. And if that wasn't weird enough,
> > > > they're upside down so I can get at the lugs.
> > > > >
> > > > > My main recommendation for battery safety using AGMs is to invest
> > in a
> > > > really good charger to prevent H2 gassing. I got a "Truecharge
> > 40",
> > > > which was about 400 odd bucks. Its microprocessor controlled and
> > > > designed specifically for AGMs, which have a different charging
> > voltage
> > > > than other technologies.
> > > > >
> > > > > We'll see if it all blows up once completed.
> > > > >
> > > > > :)
> > > > >
> > > > > Alec
> > > > >
> > > > > -----Original Message-----
> > > > > From: Warrend Greenway [mailto:dub@linuxmail.org]
> > > > > Sent: Tue 1/28/2003 1:43 PM
> > > > > To: personal_submersibles@psubs.org
> > > > > Cc:
> > > > > Subject: Re: [PSUBS-MAILIST] Battery question
> > > > >
> > > > >
> > > > >
> > > > > I know about the hydrogen venting during charging cycles. So if
> > > > > they are in the hull do you just open the hatch and stay clear
> > > > > when you are charging? Is there any problem while discharging?
> > > > > I know you have to keep the batteries dry...
> > > > >
> > > > > Warren.
> > > > >
> > > > > > Loading battery is the problem.. creates hydrogen fummes.
> > > > > >
> > > > > > Hatch should be open and airventilation by little
> > > > > > pipe on a hose should fix it.
> > > > > >
> > > > > > On a diesel-electric sub the diesel can eat the hydrogen
> > during
> > > > > > chargeing the batteries.
> > > > > >
> > > > > > Carsten
> > > > > >
> > > > > > Warrend Greenway schrieb:
> > > > > > >
> > > > > > > Hey, I have a battery question, for those information buffs:
> > What
> > > > would
> > > > > > > the overall dangers and benefits of placing the batteries
> > inside
> > > > the
> > > > > > > pressure hull be? What do you do about battery venting, if
> > they
> > > > are in
> > > > > > > water-tight battery pods? This isn't random, I was laying
> > out
> > > > parts of
> > > > > > > the OSS pressure hull and found that the batteries fit
> > neatly
> > > > inside the
> > > > > > > base of the hull. They could be sealed with an air tight
> > bolt-on
> > > > deck.
> > > > > > > Any input? Should I give this up now and place the batteries
> > in
> > > > pods
> > > > > > > outside the hull??? Any input would be great!
> > > > > > >
> > > > > > > Also, for those info buffs, what about compiling a list on
> > > > applicable
> > > > > > > battery information for review?
> > > > > > >
> > > > > > > Warren.
> > > > > > > --