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Lynn Coffelt

"Bruce in Alaska" wrote in message
...
In article . com,
wrote:

As any 32v owner knows, the advantages of 32v are great, but
unfortunately everything that is purchase from routine electronics,
weather, radios, lighting has a real premium for 32volt and the
selection is greatly limited.

snipped for brevity

Thanks much Bob

It really depends on just how much of a load you plan on running on
the NEW 12Vdc System, and how you can supply that load from either the
32Vdc Battery Bank, and, or, from the Main and Aux engines via a new
12Vdc Alternator. This design criteria was addressed in the North
Pacific Fishing Fleet years ago when the FVSA (Fishing Vessel Safety Act)
was passed, and the USCG rewrote the rules for US Flagged Fishing
Vessels. Fishing Vessels were then REQUIRED to have Emergency Lighting,
and Power for the Wheelhouse and Radio Systems, that was on the Main
Deck or higher, and independant of any source in the Engineroom.
What most vessels did was to fit an 8D or larger Battery on the
Wheelhouse Roof and run heavy Power wires down to the ChartTable
Lights, and the 12Vdc Radio Power Buss. Then the question was,
"How to Recharge the 12Vdc Battery. Three Schools of thought were
put forth. First, since some of the vessels were Main Powered from
24-32Vdc Batteries in the engineroom, they already had Numar 32-12Vdc
Converters that could supply 20Amps Continuous, to supply the MF/HF
Radio, and Vhf Radio, these were reconfigure to ReCharge the new
Emergency 12Vdc Battery, and then added the ChartTable Lights. Second,
some vessels already had a sperate 12Vdc Alternator/Battery System
fitted in the engineroom. They just ran a Charging Circuit from the
engineroom up to the Emergency 12Vdc Battery, that was large enough
to handle the Primary 12Vdc Loads, plus a couple of amps to float
charge the battery. Third, some of the vessels had 120Vac Power
from Aux Gensets that needed to be operational, 24/7, while Navigating,
anyway due to Hydrolic, or basic Systems Power requirments. A new 120Vac
Regulated Powersupply/Battery Charger was fitted to charge the
12Vdc Emergency Battery.

The only design critera that you need to really calculate, is to total
the Maximum Loads that your 12Vdc Buss is likely to see, and then design
in a small Charging current for a Battery, if fitted, plus a small
Emergency Margin in the Supply Current Capability for your New 12Vdc
Buss. The battery, in your case would be an extra advantage, and not
REQUIRED, but still would keep you operational, for a while should you
12Vdc Power source fail while navigating or at anchor, with all the Power
Souces shut down.

Bruce in alaska

Bruce, you've pretty much nailed how our fleet handled it. However
there were always some clever mechanics hired from local saloons (I'll
mention no names) that used a far simpler method. Just put the new 12V 8D on
the pilot house floor (it made a dandy foot rest) and charge it via a series
light bulb off the 32V buss on the aft pilot house bulkhead. If you used a
porcelain ceiling type light bulb socket, you could just screw the bulb in a
little to charge, and then screw it out a little when it was charged enough!
You could easily tell when the 8D battery needed charging, as the
radios were awfully quiet for a couple of hours or more. Likewise one could
tell when to stop charging by the amount of steam coming out of the 8D's
cell caps.

Old Chief Lynn (Whatcom, Nordic and Anacortes Marine Electronics)