News f2s wrote:
"Hobbs" wrote in message
...
I need to equip a sailing boat for battery charging for a single
long haul trip of about 35 days.

Anyone care to comment on the Honda Generator idea?
Any other good ideas that I haven't considered or flaws in my
logic?

*If* you decide on a petrol generator shoving out 120v or 240v,
make sure the accompanying battery charger is a modern multi-stage
charger, capable of outputting up to 14.4v (for lead acid). Only
at this voltage will you be able to re-charge reasonably quickly.
Once the batteries are up to 70% or so, the modern chargers will
sense this and cut the charge voltage to 13.6v or so to prevent
battery overheating.

This is not quite the way mine works - A modern "3-stage charger" will
output a constant Current (the bulk stage) as the Voltage comes up to
a high charging level, often 14.4 V for flooded batteries, and then
holds that Voltage steady for an hour or so (the acceptance stage) as
the current tapers off. Then it drops the Voltage to about 13.2V (the
float stage). If there is any concern about overheating, a
temperature control should be added.

My setup has a 100 Amp charger feeding 4 T-105's (450 Amp Hours). It
will keep the voltage high until almost fully charged. The alternator
regulator is also aggressive, and it will still be putting out 50 Amps
when the battery is 90% full. This is where I shut it down when
charging at a mooring, but underway it will stay in "acceptance" mode
for an hour or so.

As near as I can tell, the chargers sense that the battery is no
longer able to accept current, and then it drops the Voltage to float
level. Some will have a timer to force this to happen after an hour.



Many older chargers will only output 13.6v, and at this voltage
you will require hours of running to top up the batteries. Fine
when you're at the dockside . . .

true - I have one like that in the attic.


Most petrol gennies which output a nominal 12v, will limit their
outpput voltage to 13.6 or less, so that won't help.

The Honda has such an output, its hardly worth using.

Drive that boat a bit faster with your main diesel!
The newer alternators will put out a high Voltage at a very modest speed.