[C38] Another idea on alternators

[tdtron at earthlink.net]

Steve,

Your thoughts parallel mine exactly.  I realize every boat has different
energy needs but the main point I was trying to make, although not very
well, was the difference in charging efficiency and fuel consumption with a
high output alternator VS. a low output alternator.  The higher fuel
consumption of a higher output alternator is trade off slightly offsetting
the shorter charge times.  When I ran my engine 20 minutes a day, that was
about perfect to heat and dry the oil.  Any shorter run time would not have
produced a long enough run time to completely dry any moisture out of the
engine oil or heat our hot water heater for showers.

After we got rid of all of our energy hogs, our double bank of group 31
house batteries would last indefinitely if we ran our engine with the
original alternator 20 minutes a day and if we used a 50w solar panel from
sun up to sunset.

The biggest energy hogs we had were the refrigerator and Autohelm steering.
We insulated the dickens out of the refrigerator and added a condenser
immersed in our bilge water that made it really efficient.  There was no
way we were going to heat the bilge water with that condenser which was
just about one inch from tons of lead sitting in ocean water.

The other energy hog, the steering, was rectified by just putting a bungee
cord on the wheel to neutralize the helm when underway.  I think the simple
bungee cord trick made more difference than any other efficiency upgrade we
did.  Without the bungee cord, the steering motor would get really hot.  

The microwave was also an energy hog but we only used it a minute or two to
heat meals, never to actually cook.

Getting rid of energy hogs can go a long way to reduce energy needs.  Most
of our modern electronics consume much less than the same items did just a
few years ago.  Even radar has become energy efficient with the new digital
systems.

Tom Troncalli





> [Original Message]
> From: Steve Smolinske <SSmolinske at rainierrubber.com>
> To: Catalina 38 Listserve <listserve at catalina38.org>
> Date: 9/19/2011 1:08:27 AM
> Subject: Re: [C38] Another idea on alternators
>
> I think the best alternator for a boat is really dependant on how the
boat is used and what systems are on that boat.  In planning for Transpac
one of the first things I worked on was my power consumption.  The attached
spread sheet is what I put together based on the actual stuff I have on
board its actual draw and how long each day they would be used.  There is
an ammeter at the DC sub panel and it is so useful in showing what the
actual draw is at any given time.  One of the first exercises was to do the
Apollo 13 power savings exercise and to identify power hogs and ways to
conserve. The easy things that made a big impact where LED lights
everywhere, and a manual water fresh water pump in the galley.  After the
spread sheet was complete it allowed me to determine how much fuel we
needed to carry.   The whole idea of the power consumption exercise on
Peregrine was to minimize fuel and battery weight.  Cruising in the NW
Means that you typically motor for hours so in an average weekend or week
on the boat their is ample time for the bank to recharge.   
>
> ________________________________
>
> From: listserve-bounces at catalina38.org on behalf of Larry Malmberg
> Sent: Sun 9/18/2011 4:47 PM
> To: tdtron at earthlink.net; 'Catalina 38 Listserve'
> Subject: Re: [C38] Another idea on alternators
>
>
> Just a couple of thoughts TomT, we have sail boats and don't really run
the engines that much or shouldn't anyway.  Given the amount of electronics
one can now put on a boat, instruments, radar, chart plotters, sat phones,
macerator, bilge pumps, water heaters and so on we have become very
dependent upon our in house electrical systems and in specific the
batteries and charging systems.
>  
> For instance, I have four 110 amp AGL batteries for the house, in order
to charge these with a low amp alternator would take significant time and I
really don't want to run the engine that much, BTW I have a M-25XPB.  I do
have a Balmar regulator and it can be set to charge all the time, part of
the time and so on and to sense the battery charge level and if they are
full not to charge at all.  I would rather run the engine an hour and
charge everything up than run it 6 hours to charge everything up.
>  
>
>
>
>
>
> Best regards,
>
> Larry
>
> Team Hassle
>
>  
>
> ________________________________
>
> From: listserve-bounces at catalina38.org
[mailto:listserve-bounces at catalina38.org] On Behalf Of tdtron at earthlink.net
> Sent: Sunday, September 18, 2011 3:54 PM
> To: Catalina 38 forum
> Subject: [C38] Another idea on alternators
>
>
>
> I was doing some thinking today and it's something I don't have a lot of
practice with so bear with me.
>  
> I was going through some old stuff I had and I came across a picture of a
race car the company I worked for had.  In the '70's I worked as an
automotive technician (mechanic in those days) and I worked for a multi
franchise import store near Atlanta.
>  
> We did a lot of work on sports cars that were used in the Sports Car Club
of America racing series, the SCCA.
>  
> The rules said every car competing had to have a battery and alternator
in working condition.  At the start of every race, each car had to crank by
starter and battery without any outside assist.  Once the race started, a
starter wasn't needed any longer and the battery needed only to supply a
very small amount of current to the ignition and brake lights.
>  
> One performance trick we did was exactly opposite to what we sailors do,
we made our alternators smaller and ran the smallest and lightest battery
that would start the cars.  We took the stock factory alternators and had
them rewound to produce only a few amps of charge.  This relieved the
engine from having to pull the effort of the alternator charging the
battery which robbed horsepower.
>  
> Where am I going with this?  If we put larger output alternators on our
vessels, we can charge batteries faster but at what price?  We know high
output marine alternators aren't cheap, and we know they put more
mechanical strain on our engines and alternator brackets, water pump, etc. 
One thing we have not discussed is the extra cost in fuel by the increased
load on the engine.
>  
> At any given RPM, a 150 amp alternator will obviously cause more drag on
the engine than a smaller alternator.  If you have to add more throttle to
power the larger alternator, you are burning more fuel but at a shorter
period of time vs. the smaller alternator.
>  
> I made a 12v power generator once so we could fast charge cars at the
dealership without having to drag an extension cord and charger to the back
storage lot.  I put a 90 amp alternator on an old lawnmower deck with a
Briggs and Stratton 3hp engine running the alternator.
>  
> It didn't work!  We had to put a series resistor in the field line to
reduce the charge output to keep the alternator from stalling the engine. 
We thought 3hp would be sufficient but evidently not.  It was an eye opener
for me to see how much horsepower it takes to run an alternator connected
to a discharged battery.
>  
> If you are running a Universal 5424, 3 hp is about 12.5% of the 24hp
redline throttle, or in another way, it's about 1/8 of your total engine
power.  Since my alternator stalled the 3hp engine, the actual load had to
be more than 3hp.
>  
> Since our original alternators only put out about half of the amperage of
my experiment alternator, that 3hp would still be over 6% loss of engine
power on a 5424.
>  
> My point is, the faster charging large alternators will charge faster but
it remains to be seen how much they save on fuel by their shorter run
times.  Of course, if that 150 amp alternator destroys your water pump,
mounting bracket, belt, etc., you will save a lot of fuel because you will
be sailing home without an operable engine.
>  
> Any comments, thoughts, etc?
>  
> Tom Troncalli
>  
>