At 08:13 PM 06/26/2000 EDT, you wrote:

    << snip>>

Arild replies:

Reid

When you  have batteries in series the voltages add up;  but the amps stay
the same.

When  you have  batteries in parallel  the voltage stays the same but the
amperage adds up.

So  when you put two  6 volt batteries in series you get 12 volt but the
amperage is the same as one battery.

You said:

Use the  reserve amps value for calculating capacity.    Mind you;  the
battery bank can only be discahrged to 50% of its total  capacity.  If you
put two  8D in parallel you can only  get  450 ( ?? )  amps  from the total
bank before you have to recharge.
That 450 sounds kind of  high for a regular 8D  battery.

you said:

That is typical.  The 6 volt batteries  are specially  designed for  long
term discharge  at moderate current levels such as you get in golf carts.
See Joe Engles posting on that issue earlier.  He refered to Peukerts
numbers and formula.

Amp capacity  is a function of  volume and weight.  The best  batteries
are very densely constructed  and thus  very heavy.  The lead acid
technology hasn't changed much in the  past few decades.  What has changed
is how the  plates are arranged to resist  warping, dissolving and  getting
sulphated.
Flooded  wet cells provide highest cranking amps for a very short while,
but  do not  stand up to deep discharge for prolonged periods of time.

Gell cells also use  lead acid but the electrolyte is gelled and therefore
splash proof.    Gel cells can not deliver high peak  currents like a
flooded cell can, but they do  stand up to deep cycling much better.
You can also  charge a flooded (wet)  lead cell  harder than  you can  a
gel cell.  In fact  it is normal procedure to  "equalize" a flooded cell
by deliberatly  overcharging the  cell until it  gasses. This causes a
revesal of the sulphate that  build up on the plates  as a normal  result
of the  discharge process.
Please note that  you should not equalize a gel cell.

Reid said:

start a

Dual purpose  is a compromise.  In this example you talk of  205 reserve
capacity MINUTES , not  Amperage.
Is ther a typo here or in the previous example?
Reserve  capacity  in mimutes refers to a  constant  discharge at a
specified amperage ( 20 amps?)

As for starting  a 5 Kw genset.  Even a small Group 27  battery  is
sufficient.
I have started a 11 KW four cylinder Westebeke diesel  using a 18 Amp -
hour battery.

Reid asked:

Probably not, it's a compromise.    However, unless you specify  your
criteria for  what is BEST, it is hard to  say what is.

Some people consider the  presence of liquid  acid an extreme hazard in
addition  to  the presence of hydrogen gas when a battery  is gassing.  For
that reason they  are willing to compromise the  peak  cranking  amps  to
get the relative safety  of a spill proof gel battery.
A newer technology is called  absorbed glass mat or AGM  for short .
Although much more expensive  this type battery  seems to  offer benefits.
Mind you  other list members  have indicated  that  not everything is
perfectly great with AGM batteries.

Golf cart batteries ( 6 Volt )  which are designed for prolonged deep
cycling at moderate current levels  offer  the best power density  in lead
acid technology.  These batteries are probably the best  bet for  running a
big inverter and then getting  recharged with a large 100 amp charger when
you are tied up to shore power or have the  genset running.
To minimize genset run time you  should have a 3 step smart charger  which
typically  shortens recharge time  to about 2/3 compared to a regular taper
charger.  And a smart charger will not over charge a battery  like a taper
charger does.

Starting batteries  only have to produce peak  amps for about 15 - 40
seconds  to start  even a cold  diesel  using glow plugs.
Therefore you do not need particularly big  batteries to start an engine.
It would be better to  have  less capacity  in cranking batteries and more
capacity in house batteries.  As long as you can  start your genset to
drive a battery charger  in the event  your main battery  goes flat then
you could even get away with  having  the house bank  also serve as the
starting battery for the main engine.

The  real reason for having  your house bank as big as possible is that
you  reduce battery  life the deeper you discharge a battery before you
recharge it.  So;  the bigger your house bank, the less you discharge it
as a percentage  if you use a set amount of power before you  recharge  the
bank.

See  the earlier discussion along this topic line.

For more details on battery technology, check out some of the
manufacturer's web sites.  Their FAQ  and tech  tip sections provide a
wealth of detail.

Regards

Arild

Arild's posting on this topic says it all.  If we can have a
Lehman (Guru), my vote for battery/charging/regulator/inverter
Guru is for Arild!  His approach is practical, realistic, proven,
uncomplicated, the least expensive and 100% KISS.

My observation is similar and in agreement with Arild's, the following
is an example of my boat and others:

My CHB 45, like most boats in her class, came from the builder with
one 8D for each engine and one 8D for the house and one
group 27 (or smaller) for the genset.

The problem with this setup is that you have huge (and heavy) starting
batteries just sitting there sulfating and the poor little housebank
overworked and grossly undersized. Soon, all 3 banks are
short-lived and ready for the dumpster!

We are seeing (at my marina) more and more boats doing
what was once a NO NO -
and that is doing away with dedicated starting batteries and
making a combined housebank out of 4 to 6 (or more) golf-cart
batteries to serve as BOTH starting and house batteries.  The batteries
do not even feel the short burst of power needed to start a healthy diesel.
So goodbye to the main's dedicated starting batteries!

Even when Murphy's Law play's its part and we kill the house bank -
we still have the genny to charge the batteries or hot shot the main.

Now I only have 2 banks to look after instead of the 4 my
twin engine setup once had.  This setup allows for a very big
house/starting bank at no additional (or even less) cost!

(snip)

Brian Hall
CHB 45 "Any Sea"
Baltimore

Brian Hall wrote:

Brian, what you propose is not safe, and very likely will get
someone in trouble, sooner or later.

I had one 8D, dedicated to the single 135 Perkins, and one 8D house.
I don't know how old this batteries were, as they came with the Monk
when we bought the boat in the summer of 1997.
Just looking at them, I feared the day that they had to be replaced!

Well, a few weeks ago I replaced the house with three banks of
6 volts in parallel, PLUS two 6 volts dedicated starting bank for the
main engine. I joined Sam's just for this purchase, as neither
Costco nor BJ's carry the 6 V golf cart's.

A year ago we had a 5KW Westerbeke installed.
When I saw Reid Gantt's original posting the red flag went up, as he has
a similar genny in his boat.

11.2 VDC charge to the new group 27 battery. The Westerbeke mechanic said
"Don't worry, it's OK. The batt. is charging just fine"

We found out later that there is a problen with the back end of this
units, and Westerbeke will fix it as soon as we can arrange access to
the boat.

Meanwhile, the generator dedicated battery barely lasted the season,
and twice in the fall I had to jump start it from one of the old, worn
out 8D's. Even the battery charger was not enought to charge the
group 27.

So you see, Brian, I realize that we all are experts in our own opinions,
including myself!
But Mr. Murphy is always one step ahead of us, and considering the
small cost ($90.00 at Sam's) of a dedicated main engine starting bank,
why not have one available?

Dan Lobera
Kent Island, Md.

Quoting Daniel Lobera capdan@erols.com:

will get someone in trouble, sooner or later. . .
<< snip>>

meter indicated only

<< snip>>

back end of this

arrange access to the boat.
<< snip>

considering the small cost ($90.00 at Sam's) of a
dedicated main engine starting bank,

Arild comments:

You are forgetting  the original issue which was  not
having enough room  for all the batteries.
Secondly,your example simply reveals the pitfalls of
not having equipment which is maintained in  correct
working order.

Any design  is based on  the  equipment working as
intended and being maintained in working order.

Murphy not withstanding,  if you have limited room for
batteries, and you  do have a large inverter charger,
Some compromise is inevitable.
Having a larger house bank and relying on it for
starting is still sound energy management- PROVIDING
you also keep your genset  maintained in good working
order.

Cheers

Arild

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At 11:17 AM 06/27/2000 -0400, Daniel Lobera  wrote in an earlier posting

Arild writes:

Dan brings up a good point.
When you buy a new product  you  should be able to expect that  product to
work as  designed and  intended.

So why doesn't it?

Being in the business of working  exclusively  at  dealing with  customer
problems  or anticipated problems I know first hand how many  poorly
trained  elecrtical  people ther are out  in the mmarine business.

Yesterday I had 4 phone calls from "electricians" who did not understand
how to install our products and were asking for assistance.
Last week I  had to deal with two factory installations that  were giving
the owners fits due to malfunctions.
In both cases I was able to  determine the cause and advise the  techs on
how to fix the problem.

In each case the root cause was lack of training by the staff.  Most
companies do not provide training for their staff, and  the working  people
do not have the funds or time to  spend a month  at a factory school on
their own.
My  training and experience comes from 25 years of working  in the field
and having an insatiable curiosity.  My first inclination  when confronted
by a new peice of equipment is to take it apart.  I even  pick up  junked
stuff just to have it for  disassembly and examination.

So what  can you do  as a boat owner?

This  list is a good  step in the right direction.  Building up a
comprehensive  manual  on your own boat  is another.
Being knowladgable  or at least finding a trustworthy  service shop to do
the work for you  is another good step.

Does anyone  else have any some  stories about  disasters or near disasters
which  began with a minor failure that escalated due to lack of knowledge.

Cheers

Arild

disasters

To Arild and All:

"Dum dee Dum Dum---The names and places have been changed to protect the
innocent. No manufacturers or installation personnel shall be named. And of
course I am referring to the experiences of a friend. Therefore, I CANNOT
ATTEST AS TO THE VERACITY OF THESE "FACTS".
Two more logic representations:
From henceforward," I" equals "my friend".
"            "                , "my friend" does not equal "I".

I feel that I am a knowledgeable boat owner. I have put in electrical
systems, rigged masts and booms, put in an engine, heating systems, heads
and done all of my general maintenance.  About one year ago I decided that I
wanted
a hydraulic bow thruster
a    "          windlass
Hydraulic stabilizers.

Now comes the confession. I did not know anything about hydraulics except
that they could be powerful and that they would not "time out " as
electrical motors are apt to do. I had not the foggiest idea of the
magnitude (or the space) that this project would entail. And the people who
sold it to me gave me no indication. I spent hundreds of hours drilling 4"
holes , modifying cabinets and pulling about 300 feet of 2" to 5" diameter
hydraulic hose throughout the boat. Then I pulled all of the wiring
harnesses for the system. I thought this might reduce the original cost
estimate. Not so! My efforts must have been a hinderance as the bill ROSE to
$50,000.
O.K., So now I have a system --sort of. After every day of use, the system
failed for a year. We always got service, but "they" could not get anyone
here for 2 to 6 weeks. We lost one full year of boat usage screwing around
with the installation and the people we were dealing with. All of our
letters went unanswered to this day.
Back to the main point. If I had been a very technically competent person to
deal with hydraulic system questions, I think this may have gone better.
Rather than hire an independent "general contractor", I relied on the
equipment manufacturer--Bad idea!
I hpoe this helps someone.

Cheers!