I have a 44' standard class house boat reserved for Lake Powell. I
want to be able to recharge a deep cycle marine battery (group 27) for
a trolling motor.
I am especially concerned about overloading any aspect of the boats
electrical system or breakers. I would only connect the battery for
charging when motoring.

Should I
a) use a 12V to 110VAC inverter and a 110V battery charger connected
directly to one of the house boat batteries - this seems inefficent.
b) connect the battery in parallel with one of the house boat
batteries - is this too much of a load?

Thanks, james

james wrote:

Should I
a) use a 12V to 110VAC inverter and a 110V battery charger connected
directly to one of the house boat batteries - this seems inefficent.
b) connect the battery in parallel with one of the house boat
batteries - is this too much of a load?

I'd say "b", but with the addition of a suitable DC light bulb in series
with one lead of the wiring to act as a current limiter. Connecting a
discharged battery to a fresh one could cause excess current and even an
explosion. A 50 watt bulb, like a car headlight bulb, will limit the
current to about 4 amps and, best of all, will go out when the charge
equalizes enough that current drops to a safe level and it is no longer
needed. Then you can safely keep your trolling battery in parallel with
your house battery, ready to go fishing.

On 29 Sep 2003 09:00:40 -0700,
(james) wrote:

I have a 44' standard class house boat reserved for Lake Powell. I
want to be able to recharge a deep cycle marine battery (group 27) for
a trolling motor.
I am especially concerned about overloading any aspect of the boats
electrical system or breakers. I would only connect the battery for
charging when motoring.

Should I
a) use a 12V to 110VAC inverter and a 110V battery charger connected
directly to one of the house boat batteries - this seems inefficent.
Unnecessary.....

b) connect the battery in parallel with one of the house boat
batteries - is this too much of a load?
Only with the engine running. The dead battery will suck dry the hot
battery if the charger isn't running.

An alternator will only put out X amps....even into a short, which is
what a dead battery really is until it gets charging. If you have a
90A alternator, it puts out 90A until the voltage rises, which in a
small battery will happen very quickly, dropping the current very
quickly. It doesn't care which battery is absorbing all this juice.
It just produces it.

Now, if I were going to do this, I'd go over to a boat supply or a
motorhome supply and buy a solid state battery isolator, myself. That
keeps the good battery from being in parallel with the dead battery,
isolating them from each other while allowing the alternator to charge
both. Hookup is simple.....you change the charging (heavy) wire from
the alternator just like it shows in the isolator's instruction
sheet.....

| --------------Original Battery
|
Alternator---Isolator
|
|----------------Trolling Motor Battery
(dead or alive)

Then, you can leave the trolling motor battery hooked up to the
houseboat all the time. Also, if you disconnect your AC charger from
the "Original Battery" and hook it to the Alternator terminal of the
isolator, it will keep both the original battery and trolling motor
battery charges topped off and READY TO RUMBLE because it will charge
them both through the isolator....(c;

Make darn sure the + charging lead for the trolling motor cannot touch
grounded anything when the trolling motor hooked up. That would short
the alternator and the house charger....not good.








Thanks, james


Larry W4CSC

3600 planes with transponders are burning 8-10 million
gallons of kerosene per hour over the USA. R-12 car air
conditioners are responsible for the ozone hole, right?