I was sitting here tonight talking with Debbie about my recent post  on our
design adventure and, in doing so, I realized that I would be horribly
remise not to mention our very own listee, Arild Jensen, who I got involved
after the Kasten design was nearly finished and right as were selecting a
builder.

Arild explored some alternative get home, electrical propulsion ideas I had
(that in the end were not practical), but in doing so I hired him to design
the electrical details of Passage of Time and he did a marvelous job.  It is
an often overlooked area that is most frequently left by the designer to the
builder.  Arild really focused me on the entire electrical setup, looked at
what I had put on my specifications list and made some hugely significant
suggestions in changing the refridge and air conditioning system components
for better energy usage.

In the end I think I ended up with a very elegant electrical design that I
am thoroughly delighted with and which is in many respects quite unique.
Thanks to Arild, I was able to scrap the third engine (the stand alone
generator).  My "get home" engine doubles as the generator, but delivers DC
power, not AC, to the batteries and the inverters via two huge alternators
(it's a 24v boat).  The John Deere main engine has an identical pair of big
alternators, so whenever the main is running the entire boat is fully
powered as if there was a generator running, but there isn't.  When the main
is running, for instance, the air conditioner is available if we want to
stay cool, without the need to start the generator (the wing).

Arild was a gold mine of help on an extremely important part of the design
and I hope that he forgives me in failing to mention him before this.

Alan Wagner
Tampa
With Passage of Time under construction

Alan,

How "huge" are those alternators and can you disengage them when not needed?

Also, how does the heat of the engine room affect them?

Regards,

Bob Frenier

Alan,

How "huge" are those alternators and can you disengage them when not needed?

Also, how does the heat of the engine room affect them?

Reply:

The AC power on board will be 220V/230V for all high power equipment.

The alternators are a pair of Balmar Series 98 24v 170 amp  alternators
running in tandem to provide the power.  At 150 Amps output, each alternator
delivers 4.1kW or 8280 watts total for both.  Even when the inverters are
full loaded there is a reserve of 2.8kW for charging batteries.  The tandem
alternators are powered by the 30 hp Kubota wing engine that will double as
a generator when needed.

An identical pair of Balmar alternators are run from the main engine, so the
"generator" is not needed while underway.

Fully loaded, the alternators will require 12 hp and the regulator -- as I
understand it -- reduces the load with reductions in power requirements,
although they are not disengaged.

My engine room is pretty well ventilated so I don't think heat is a problem
and the alternators are designed, obviously, to be used in an ER environment

Alan

<How "huge" are those alternators and can you disengage them when not
needed? Also, how does the heat of the engine room affect them?>

All of our AC loads run from our 2 4KW 4024 Trace inverters which are fed by
our 24 volt 800 AH house bank. The house bank is either charged by the
genset running thru the inverters or by our "big" alternator.
"Big Red" is a 275 amp 28 volt Electrodyne alternator belted to the main
engine with two Gates Predator belts. We limit the alternator to 175 amps
(5kw) with the Balmar 624 regulator and it runs cool (140-150 F) and the
belts are holding up fine.

The output is sufficient while we have the main engine on to run all of the
Air Conditioning loads and the rest of the boat while underway. The genset,
which is automatically started if the batteries reach 24 volts for 15
minutes, never starts while we are underway.

The outputs of each inverter is fed thru an EMS load shedding breaker panel
so the inverters are never loaded beyond there capacity (33 amps). This
system has worked well for in past for us and is quite simple and requires
no manual intervention unless you wish too. Manual operation usually leads
to a problem as my "CRS" keeps progressing. I find carrying an egg timer
when I am transferring fuel around saves my bacon often ;-)

We would like to find an all voltage 50/60 cycle battery charger in the
4-5KW range that we could install to be able to use dock power anywhere.
Can't seem to find anything of this nature that would work for us.

We also have thought of a 5-6kw DC genset to put into the system to gain
some efficiency over using the 10 kw AC Genset when we are running the
washer/dryer, and other heavy loads.

We don't seem to notice increased fuel consumption of more than .2gal/hr
when the alternator is running at the 5kw output level vs. being off
underway. This same level output requires about .5 gal/hr running from the
AC genset. Big difference in 24 hrs (7 gal) or 10 days (70 gal) or 30 days
of operation (210 gal)!

Dave & Nancy
Swan Song
Roughwater 58
Caribbean Cruise '07

<Alan wrote: Why such a big alternator if you only use it to put out 175
amps>

These are 175 amps at 28 volts (5 kw) or the same as 350 amps at 14 volts.
The Electrodyne uses very large external diodes that are generic and easily
replaces. The entire assembly is rated for 20,000 hours between service of
the bearings, It puts out the full rated amperage (250 amps) at 28 volts at
2400 rotor RPM. We run it at 2 to 1 so at 1000 rpm we are turning it at 2000
and it still gives us the 175 amps if we need it. At our normal cruise RPM
of 1250 its at 2500 and is very cool and happy.
These specs can't be touched by any other alternator that I have been able
to find.

We limit to 5 kw as this is getting close to the belts max hp power they can
handle. The only belts (2) we found that are up to the task are the 1/2"
Gates Predator which are Kevlar. Surprisingly cheap yet really do the job.
Very little stretch so little adjustment is required as they age.

The Balmar regulator has many adjustments and also has both battery and
alternator case temp sensors. It's a very good unit, IMO.

Any regulator should be able to run any alternator as long as the alternator
only looks for a field input. The regulator has all the smarts to handle
everything else.

Electrodyne really isn't in the marine business...their products are for
industrial, coaches, emergency equipment, etc applications. Stuff that has
to work under extreme conditions for long period of time.

So big bearings, lots of copper and a very robust yet simple design.

As always YMMV....

Dave & Nancy
Swan Song
Roughwater 58
Caribbean Cruise '07