more battery stuff

[VBra676539@aol.com]

Al and all,
	I called an old bud of mine at Harbor Branch today to ask him some 
battery questions.  Dom Liberatore is the HBOI Chief Pilot, and has been 
there for twenty years.  Of course, the weirdest news was that he just last 
month sold the old Datsun pickup that he and Greg Kennedy and I used to 
commute to work in--in 1981!--and it was a rambling wreck even then!  The 
other news had to do with their sub Clelia which is the Perry PC-1204 that I 
did 300 or so dives in back in the North Sea construction days and which has 
been resurrected for science.  Didn't they buy it from you, Phil?
	They (HBOI) are using GNB Maintenance Free batteries of a reputed 100 
ampere capacity--two strings of 10 batteries in each battery pod--40 
batteries in all.  They have a vent system which allows them to whistle 
outside air in and out of small tubing and charge batteries (when on a 
mission) with the battery pods closed.  They do this because they had never 
had anything even remotely like a Perry-boat, and nothing with dry batteries 
in pressure vessels.  The idea of opening those pod hatches at sea made them 
nervous.  Hell, we used to pop those babies after every dive to vent while 
charging, and they never leaked, but HBOI is used to compensated batteries on 
the JSLs, and they only crack those boxes during annual overhauls!  They just 
ain't used to seeing batteries, don'cha know?
	Anyhow, Dom says that the Maintenance Free GNBs have held up fairly 
well, with only 2 or 3 fried cells he can recall (during missions).  The 
problem, comma, is that the battery strings are very finicky to charge.  
Their charge rates are funny because they DO HAVE a catylator built in to 
recombine hydrogen with oxygen (how else would they be maintenance free?), 
but DON'T HAVE the capacity to do this very quickly.  Also, the units are 
rated at 100 ampere hour but in real life only supply about 80.  They have 
thin plates, which I have talked about elsewhere, and just won't stand for a 
great wolloping charge without warpage and boilage and wreckage.   Of course, 
HBOI has a special set of digitally controlled chargers built by GNB to deal 
with this.  Kind of makes you wonder what those babies cost, doesn't it?  The 
chargers failed once and cooked an entire double  string of batteries to a 
Kentucky Fried extra-crispy order.  GNB replaced them all, but it sure put a 
crimp in the sub operations for a while!
	All things being equal, and they never are, Dom reckons they are 
pretty happy with the system they are using.  Of course, they have more money 
than I have opinions (which means they have a LOT of money!).  For us little 
guys, it might be best to think of those tough old golf carts, with the tough 
old 6-volt batteries.  You get complete control of each cell's gravity, lots 
of power, and you make Trojan or Sears very happy.  Does it get any better 
than that?
	And for all you detail cranks out there, a standard Perry battery pod 
is basically schedule 40 pipe, 20 inches outside diameter with 1 X 2 inch 
ring stiffeners every 30 inches (welded wide side down) and are120 inches 
long with a momsom clamped hatch on each end.   The big boats (PC-9, PC-15, 
PC-1202 and both 16-boats) all had 182 inch pods.  PC-9 carried an entire 120 
volt string of 225 amp Trojan 6-volters IN EACH POD!!!!  1200 pounds per 
side!  Yikes!  I once did 13 hours and 15 minutes on one charge, running a 
pipeline in the Shetland Islands in the 9-boat.  It was terrible.  The coffee 
got cold before we got done and man, I hate it when that happens.
Best Regards,
Vance