I am designing a vehicle that needs to have the longest possible run
time.  The vehicle is designed to run off of a 12v system.  The
vehicle has two spots for batteries each of which is 14" long x 8"
wide x 10" tall.  I would like help finding the best battery for the
job.
The vehicle will be deployed at 4000 meters underwater with an ambient
pressure of 6000psi so the battery and pressure housing will have to
fit in that spot.  I hear if its a Lithium Polymer battery it doesnt
need a pressure housing that since its solid its imune to pressure and
just needs its leads sealed.  Also i hear some of the other batteries
can withstand the pressure but just need to be modified with a
non-conductive oil instead of air.
Keep in mind price is always an issue so i need the solution to be
affordable ($500 ±$200).  Also I need to know the best places to get
it.  *Note this is for a senior design project (both tax deductible
and media coverage for sponsors) so if you know a place that will
donate an even better but more expensive power supply please let me
know.

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Request for Question Clarification by pafalafa-ga on 09 Mar 2006 19:45 PST

Electrovaya reputedly makes the highest energy-density batteries that
are commercially available, using a proprietary process.  Most of
their work is for extended-life laptop batteries, but they also do
work for NASA, electric vehicles, specialty applications, and so on.

I have no idea what the price might be for something to meet your
needs, but check them out at:


http://www.electrovaya.com/innovation/battery_tech.html


Let me know what you think,


paf

Yardney in Pawcatuck CT makes such abattery. They won't be able to
talk to you becasue the details of the program are classified, but the
declassified bits (from a lawsuit with a competitor) give a hint about
it.

However, your price is about as far from realistic as possible. The
lawsuit hinted at a mutlimiillion dollar contract (though exact
numbers were redacted, there were enough clues to get an idea).

Oh, it doesn't mention go into size, by the way.

I have already spoken to Yardney and it seems their solutions are
quite pricey (also Yardney doesnt make the Lithium batteries, they
only make Silver-Zinc batteries, its another division Lithion Inc, is
the one that makes Lithium Ion batteries but i dont think they make
Lithium polymer batteries).