Re: [PSUBS-MAILIST] battery acid? & battery issue follow up

Curious to see what kind of answer I might receive, I posed the question of the leaking batteries to Pat Regan on his website message board. His reply was very informative, and one thing he pointed out was that AGM batteries can vent when overcharged. You might want to read his commentary.

Pat also mentioned he chose AGM batteries because his Nautilus submarine has what he called a "hydrobatic ballast system" which he says allows him to operate at various attitudes including upside down. If I understand correctly, this sub has been working since 1991. Pat seems highly experienced with the kind of ballast system problems you've mentioned. Perhaps you could ask him for some pointers. Here's his URL:

NeophyteSG@aol.com wrote:

In a message dated 2/16/04 5:47:29 AM Pacific Standard Time, Asmyth@changepoint.com writes:

Because Solo is intended as a "flying" sub, it's designed to have a very small self-righting moment. [snip] If Solo had conventional stability, she could never roll or fly inverted.

Totally understand. My design is facing similar constraints except that all my nonessentials are fared external to the pressure hull which, Sgt. Pepper-ish, is much smaller than yours appears to be. In my case, I'm juggling axiometric placement of everything in the horizontal and vertical planes through the hull's longitudinal axis, leaving the drop weight(s) placement until near the end to essentially force the righting moment equations to balance. I also liked the idea of essentially being able to use just about everything except the pressure hull as a drop weight should the absolute need arise.

What gave me a worse headache was trying to figure out a functional ballast system for a craft which will hypothetically have six degrees of freedom, won't "slosh" around (changing the center of buoyancy), and will work no matter what the orientation of the craft ... including upside down.

Given the batteries are snug against the hull "ceiling", I can't reach the lugs to connect the cables unless they are upside down. Plus, I don't want the lugs shorting out against the hull. If they cannot go upside down, I'll probably have to lower everything by about 3". Plus, all the cables will now be a few inches too short.

Aside from simply not having the room, you're making me glad that I chose to mount all but the two emergency reserve batteries outboard ... not meaning to take pleasure from your pain. :)

In a message dated 2/16/04 7:00:24 AM Pacific Standard Time, Asmyth@changepoint.com writes:

FWIW, possible KISS solution: Incorporate a pivot and latch into the mounting hardware whereby you can drop them down into an upright position for charging -- when you won't be occupying that space -- then latch them back upside down and against the hull during dives. If the current cabling reaches the lugs in their upside down position, you won't even have to lengthen them because they'll just need to rotate 180-degrees. Make sense?

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