[PSUBS-MAILIST] Battery boxes

Thu Dec 19 16:48:12 EST 2013

Vance,

On my cabin cruiser, I ran lead acid because I did not like the cost of the higher end batteries. Of course gasoline fumes are more of a concern in a bilge than H1. Recently, I've been pricing the AGM's at West Marine and other places and not liking what I've seen, and this seven years prior to my build so imagine then. It seems to me that the batteries for a PSUB are the single most expensive repeat consumable item, so I'm very much liking this method.

The Busby text (pg. 325) says that 48% of the submersible fleet at that time used this method compared to 32% inside and 20% external pods. This not being my line of work, I have to figure there are sound reasons for this being the case, I'm a believer in paying attention to what industry does in whatever discipline.

Looking at this over and over I have been coming to realize that the biggest advantages gained for a homebuilt affair are in cost, size and weight at the expense of convenience. Additional gains as you mentioned are lowering the CG with a concurrent gain in stability, jettison capability, and a added streamlining benefit along centerline, a standard K-350 tracks very poorly when towed as evidenced by builders on this very forum multiple times in the past. Add to this configuration a stabilizing fin ala Nautile, Shinkai, or even Delta, and a very towable submersible with a stable submerged station keeping ability in local conditions starts to emerge,. I'm liking it!

Thanks for that very helpful post.

Joe

On Thursday, December 19, 2013 3:27 PM, "vbra676539 at aol.com" <vbra676539 at aol.com> wrote:

Joe, 

In the short form, the answer is yes. And you have described possibly the simplest, cheapest, lightest, most compact, and most Ace Hardware friendly power pack possible. Be advised: I know zip about compensating AGMs, so this is about wet cells. 

You wouldn't use hydrocaps. What you want is what we called "bubbler scrubbers". A screw on top with a can on it (about the size of a 35mm can) filled with small pvc beads and drilled through the top like a salt shaker with holes slightly smaller than your beads to keep them where they belong. Any hydrogen bubbles rising out of the cells will be wrapped in acid, and the bubbler is just a way to scrape the acid off as the gas moves through so you don't get it into the compartment. The acid sinks back down into the cells and saves you having to service the batteries so often. On the JSLs we only took the battery apart annually, or if a cell failed (which I personally never saw happen). 

The nice thing about the acrylic top and separate compensator is that you can see the batteries and the condition of the oil. The JSLs have an inch thick top with a slight bow in it so there is a high point for a relief gas valve. They also run the electrical penetrators through the top itself. I like the plexiglas better than a membrane and I have NEVER had trouble with a compensator bag. You can make one out of a 3 quart ice pack bag from the drug store. It just ain't that hard. 

As to operations with a compensated battery--okay, it CAN be a mess. Doing maintenance takes planning. You have to pump or drain the boxes to a drum and remove the top and yup, it's all oily and shit in there. Keep the shop rags handy. You'll need them. Did it more than once on the JSLs, Leo, and Pisces V. What they don't tell you is that it's not such a big deal. You just have to plan on it. 

Overall, it's cheap and easy. That's the big draw, especially for shallow boats, where pods and all that add complication and expense. A K-sub, for instance, could have a half dozen 220 amp Trojans in a single string in one box for 36 volts. The box would be about  12"X12"X36". You could even make it droppable, and it would be simple to do. 

That's a lot of power for one little box, and a lot of power for the normal needs of a K-sub. You could hang it between two 1' deep skids, lay your external HP bottles alongside and fair the whole thing into a nice tidy little package that would be streamlined and snag free and wouldn't make the hull sit any higher than it already is. Plug the batteries into the hull and be on your merry way for about...oh, what do you think? Two grand? And it would make a very neat little package, plus make the boat plenty stiff to offset rolling. The box would displace about 200 pounds in seawater and weigh...um...call it 500# air weight, so not a bad compromise for a battery like that.  

As to cables, which are horrendously expensive in high voltage variants, just have a look at what Snoopy got. Those are a mild upgrade from the bulkhead pins that HBOI used on the JSL battery boxes for nearly 40 years!!! Hard to beat that for field testing. And you can make 'em in your backyard shop on a Chinese lathe. 

Vance

-----Original Message-----
From: Joe Perkel <josephperkel at yahoo.com>
To: Personal Submersibles General Discussion <personal_submersibles at psubs.org>
Sent: Thu, Dec 19, 2013 1:02 pm
Subject: Re: [PSUBS-MAILIST] Ictineu 3 launch

I notice some similarities as well as significant differences between that battery module and the Deep Sea units we've seen and discussed before. Aside from the lithium technology of course. 

Of note are the oil filled case, the case itself, and the transparent flexible membrane covering the whole works. The difference that catches my eye is that the electrical penetrations are through the case as opposed to through the membrane like those other units. That's significant because to my eye going through the case looks to me to be easier and more trouble free leak wise for the homebuilder. 

So my "idea man" brain has a question for the shop wizards.  

Can a low cost relatively lightweight trouble free power module be reasonably built using?,.... 

1) Low cost lead acid batteries with hydro-caps 
2) FRP case with appropriate penetrations through the case 
3) Oil filled case with membrane as opposed to reservoir compensation 

My thoughts are two independent battery boxes in tandem along the centerline, possibly jettison-able. 

Joe 

On Thursday, December 19, 2013 12:21 PM, "jimtoddpsub at aol.com" <jimtoddpsub at aol.com> wrote:

Couple of links for Ictineu 3.  Video has subtitles (pause, start, pause, etc.). 
http://www.ictineu.net/en/ 
http://www.youtube.com/watch?v=fF_6txom_wI 

-----Original Message-----
From: vbra676539 <vbra676539 at aol.com>
To: personal_submersibles <personal_submersibles at psubs.org>
Sent: Thu, Dec 19, 2013 10:34 am
Subject: [PSUBS-MAILIST] Ictineu 3 launch

The brother and sister team has finally water dipped the sub and done preliminary submergence and thruster testing. The announcements came out today on social media (FB, etc). It's worth looking them up if you haven't done so already. I talked to them for awhile at UI last year, and this thing is seriously impressive. 1200 meter depth capability with a big window, no less, and it only weighs 5 tons. That's pretty good going for a crew of three. Plus some really good looking lithium polymer technology. 10 kw/148 volts from a single box that isn't all that big or heavy (which they are advertising as for sale separately). Overall, it's a real beauty. The builder/designer is a fiberglass guy, and the fairings and whatnot are sheer art. Very nice.  
Vance   
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