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Mark Borgerson

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Those of you who followed along with the updates from our Caribbean
cruise earlier this year, may remember that we experienced some
alternator issues along the way. This was disappointing for a number
of reasons because we had already spent a fair amount of time, effort
and boat bucks trying to find a high output alternator that was also
durable.

Our goal is to not run the generator at all when under way, and to
minimize generator time when anchored. The potential savings on
generator fuel and maintenance add up to a big number. To that end
we've installed a 2,000 watt inverter and a bank of 8 golf cart
batteries with a total capacity of about 1,000 amp-hours.

The inverter and battery bank work well together but the batteries
eventually need to be recharged, and when underway, the alternator
needs to supply inverter amps, recharge amps and onboard house loads
like navigation equipment, lights, auto pilot, engine room blowers,
etc. Peak alternator loads can easily approach 250 amps and average
well over half of that.

To make a long story short, no automotive alternator that we've tried
has been capable of these loads over a long period of time, even those
that have been beefed up with heavy duty components. We burned out a
total of 4 over the course of 6 months in the islands. Repair and
replacement was problematic to say the least.

After consulting with Tim, our cheerful, ever helpful, resident
alternator expert on "rec.boats", and a number of other sources, I
decided that a fresh approach was needed. Enter a company called
Leece-Neville, a division of Prestolite, that has been making heavy
duty alternators for a long time. LNs are used all over the world on
fire trucks, ambulances, busses, big trucks, heavy duty construction
machinery, etc. Their big alternators make everything else look like
a toy, weigh over 35 pounds and are priced accordingly. Many of the
really big ones are north of $2K at full retail. Thanks to the
internet and EBAY however, they are now becoming available at more
reasonable prices. I was recently able to buy a unit that had been
remanufactured to like new condition for about $400, a bargain
compared to some of our previous repair/replace experiences. It is
rated at 270 amps continuously at high temperatures, and is designed
for fire trucks, ambulances and busses.

http://www.prestolite.com/pgs_products/specs.php?item_detail_id=951&item=A0014867JB&produ ct=ALTERNATOR

There are some downside issues however: It is designed for a so
called J180 mounting bracket; requires multiple drive belts since it
can use as much as 6 or 7 horsepower; and is not ignition protected
for gasoline engines.

Ignition protection is not an issue for our diesels, and fortunately
the front pulley on a Detroit 6-71 can accomodate up to three belts.
The mounting bracket was problematic however since the existing mount
was for a Delco 2 inch foot. In exchange for a sizable boat buck
fraction, a local machine shop fabricated a custom made J180 bracket
from 1/2 inch cold rolled steel. In combination with some Grade 8
steel mounting hardware and a new adjusting arm, everything is now
solidly attached, lined up and looking good with 3 brand new Gates
Green Stripe belts installed. In testing it has put out well over 200
amps while maintaining reasonable temperatures.

Stay tuned for the long term durability reports... :-)

New alternator and bracket prior to installation with a beverage can
for size reference:

http://img140.imageshack.us/img140/3557/preinstallwithnewbracke.jpg

After installation, with new HD belts and adjusting arm. The black
detritus in the background is left over from the many previous
alternators and belts which gave up their lives in that spot:

http://img16.imageshack.us/img16/1462/installedimg0573.jpg

It looks like the right piece of equipment for the job----however,
I find the washer stack and bolt on the belt-tensioning arm a
bit troublesome. There's an inch or so of lever arm and it looks
like about half an inch of thread into the alternator front plate.
If that front plate is cast aluminum, how long will it be before
that bolt loosens with thermal cycling and vibration?

For a few more boat bucks, you could replace the washer stack with
steel block of the appropriate thickness---perhaps with some filed
'tooth' on each side. Spend a few more bucks and get a bolt
a half inch longer. You might also have clearance for a thin nut
on the front to act as a lock nut.

When you're cranking out 200 amps, there's going to be substantial
load on that bracket.

TINS: Back in the 70's I drove a Chevy Vega with an aluminum
block. That never gave me problems, but I did have an alternator
problem. I was careful with belt tension and kept that bolt tight.
However, the belt kept getting looser. I finally disassembled the
system and found that the bottom of the alternator was pivoted
on a 4" long steel pin through the alternator housing. The housing
had worn away so that the 3/8" hole through the housing was now a
slot about 3/8" wide and over 1/2" long. At the belt end, you could
see the pin coming out of the side of the alternator housing.
I replace the alternator and the new one lasted until the car
was totaled by a teenager who ran a stop sign and crunched my
passenger side quarter panel.

Boat, with new alternator well hidden, docked last weekend on the
Caloosahatchie River in southwestern Florida:

http://img593.imageshack.us/img593/6797/img0567i.jpg

Mark Borgerson

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