(Mic) wrote in :


" The Preferred System

The Preferred System consists of a single house bank, and a dedicated
starter battery for all engines. A separate generator battery is
sometimes present. "

I disagree....

"......a two house bank system is no longer necessary. In fact, the
more battery banks in use, the less reliable the system will be, while
also increasing cost and management problems."

Ol' Nigel, the expert just because he has a publisher, must have a pretty
large boat. If he does, then he can have one huge house battery. But,
real boaters don't have that luxury. The batteries go where they can. One
house bank means a 130AH deepcycle or two 230AH golf cart batteries in
series because there's just no place to put them. This isn't enough power
if you have radio/radar/autopilot/refridgerator/pumps/computer and lights
running 24/7 at sea. Then, what happens if a cell shorts or opens or just
decays? Is ol Nigel gonna run it off the starting battery? I think NOT.
He's gonna sit in the dark while we go on with our redundant system of TWO
house battery banks, only concerned with a little conservation.

NASA has at least two, if not 4 to 8, of everything aboard any spacecraft.
A ship is a spacecraft...stranded in its environment with no hope of
repairs...it still needs redundancy. Even two sets of 130AH deep cycles,
which now require no maintenance, is better than one set of golf cart
batteries, which do. Nobody in a boat has too much power...especially sail

"Instead of a 1-2-both switch, a simple parallel switch can be used to
start the engine from the house bank if needed. "

Unless, of course, your NOT at the dock out there in the 8' waves where you
can't work to disconnect the shorted starting battery being beaten to death
by the sea. I use a simple paralleling switch in my stepvan because if I
have to I can stop, get out, and fix whatever's wrong. A 33' sloop in 8'
seas doesn't have that luxury, what with everyone hanging on for dear life
rockin' and rollin' just trying to keep her pointed home. A simple switch
paralleling the two banks on a shorted starting battery will simply short
the whole house. It isn't going to start.


"But, if you make the house bank from parallel batteries a cell
failure in one only knocks out that battery."

See? He answers my problem in the paragraph above. This is why Lionheart
has TWO 1-2-Both battery switches. One switch selects which house battery
powers the house. The other battery switch selects whether the house or
the starting battery starts the Perkins. If you put both switches in BOTH,
they all crank the Perkins and power the house. REDUNDANCY...always
REDUNDANCY.

I like redundant charging, too. The Perkins has TWO alternators, 80A for
the starting battery on the original engine mount and 120A on the house
batteries connected to a diode separator that charges both banks. If one
alternator fails, simply put both switches in BOTH and either one of the
alternators charges all the batteries at once. Power is our FRIEND.


"There are other positive benefits of a single house bank versus two."
"...a gain in effective capacity results because the rate of discharge
relative to battery capacity is reduced."

Nope...doesn't wash.....

The ampere-hour rating of any battery, even his, depends on the LOAD
current on that battery. The lighter the load, the higher the actual amp-
hour capacity of the battery. Put a 1A light bulb across a 130AH deepcycle
and time how long it takes it to die.....MUCH longer than 130 hours. 130AH
is the 20 amp load rating. Draw 50A off it and it's dead in minutes, not
hours, because the chemical reaction of acid and lead can only happen so
fast.

When one has two battery banks, the load current is halved on them. The
real amp-hour rating at this load goes up significantly as the results.
Nigel has it backwards!


FYI
http://www.amplepower.com/wire/dual_alt/index.html

Dual Alternator Controller

REDUNDANCY....always REDUNDANCY. This controller fails you gots NO
CHARGING! Two SIMPLE regulators reduces your total failure probablility to
near zero.

I like integrated regulators....GASP!...WHAT?!!....Integrated regulators?!
How can this be?!

The integrated, internal regulators in all your cars works just fine. When
was the last time you lost a REGULATOR when your car's alternator went out?
You didn't. You lost a brush or a more probably a rectifier diode. The
internal regulator reduces the wiring maze in the engine room, another
point of failure. The internal regulator is made for THAT alternator, not
a whole series of alternators like these gee-whiz expensive beasts with
their LED lights, plugs that corrode, etc. What is this fascination with
ever-increasing the complexity of such a simple device? Regulators are
VERY accurately controlled by Zener diodes in 2005. They've been that way
for decades. You don't need to be screwing around with "settings" on
regulators. Put 14-14.5V to the house battery and he's one happy camper!

The other thing I don't like, but Lionheart has already, is these BIG
alternators. Ever look at a battery charger? Do you charge it at 120
amps? No? Why? Battery charging chemistry is S-L-O-W! Time is your
charging battery's friend. The longer you take to charge it, the more
charge it absorbs and the safer it is for it....especially DEEP CYCLE house
batteries. Starting batteries, like your car battery, made of lots more
plates with huge surface areas to create huge currents for seconds can
charge at much higher rates than a deep cycle with its low count, thick
plates with much lower surface area. The charging current per square inch
of plate surface is the same, it's just that the deep cycle has lots LESS
surface area on thicker plates. This charging them for an hour at 100A is
absurd! The chemistry just can't absorb the current you're shoving in
there fast enough, so it rids itself of excess by getting HOT. Heat
generated at high charging rates DOESN'T charge it. You end up with a gas
station surface charge, which doesn't last. Golf cart 230AH batteries LOVE
about 25-30A of charge. They hardly get warm and the specific gravity goes
all the way up to 1.260 without percolating them. So, why do we need an
alternator bigger than 30A + the house load current while we're charging?
We don't.


Ample power......two banks of L-16s at 1.260 gravity....ahh...ample power.

--
Larry