Question for you electronics wizards...>>>

I'm running 2 12-volt batteries running in series to power my 24-volt
electric motor in my jon boat (on an electric-only reservoir) and I want to
run a fish finder. Here's my question -- can I safely run the fish finder
off of one of the 2 12-volt batteries while running the 24-volt motor? Or,
is that going to burn up the fish finder? Should I just invest in a couple
of 6-volt lantern batteries instead?

--
Marty S.
Baltimore, MD USA

On Tue, 8 Jun 2004 21:17:33 -0400, "Marty S." wrote:

I'm running 2 12-volt batteries running in series to power my 24-volt
electric motor in my jon boat (on an electric-only reservoir) and I want to
run a fish finder. Here's my question -- can I safely run the fish finder
off of one of the 2 12-volt batteries while running the 24-volt motor? Or,
is that going to burn up the fish finder? Should I just invest in a couple
of 6-volt lantern batteries instead?

One of the batteries is referenced to GROUND, the other is not.

If you connect your fish finder across the battery that is referenced to
GROUND, you should be fine. If you make the mistake of connecting across the
*other* battery, what the fish finder "thinks" is GROUND will actually be 12
volts *above* GROUND, which sooner or later will be revealed to be A Bad
Thing...

/daytripper

"daytripper" wrote in message
...
On Tue, 8 Jun 2004 21:17:33 -0400, "Marty S."
wrote:

I'm running 2 12-volt batteries running in series to power my 24-volt
electric motor in my jon boat (on an electric-only reservoir) and I
want to
run a fish finder. Here's my question -- can I safely run the fish
finder
off of one of the 2 12-volt batteries while running the 24-volt
motor? Or,
is that going to burn up the fish finder? Should I just invest in a
couple
of 6-volt lantern batteries instead?

One of the batteries is referenced to GROUND, the other is not.

If you connect your fish finder across the battery that is referenced
to
GROUND, you should be fine. If you make the mistake of connecting
across the
*other* battery, what the fish finder "thinks" is GROUND will actually
be 12
volts *above* GROUND, which sooner or later will be revealed to be A
Bad
Thing...

/daytripper

Near as I can tell in my boat, neither side of the batteries for the
trolling motor is ground. The trolling motor basically floats. So go
ahead. use the battery connected to ground if one of them is connected
to ground.

del cecchi.

I'm not sure about your answer, Daytripper. I don't have either battery
connected to ground as far as I know. The + terminal of one battery goes to
the motor, and the - terminal of the other battery goes to the motor, and
the other terminals are connected to each other so the battery is connected
in series.

--
Marty S.
Baltimore, MD USA


"daytripper" wrote in message
...
On Tue, 8 Jun 2004 21:17:33 -0400, "Marty S." wrote:

I'm running 2 12-volt batteries running in series to power my 24-volt
electric motor in my jon boat (on an electric-only reservoir) and I want
to
run a fish finder. Here's my question -- can I safely run the fish
finder
off of one of the 2 12-volt batteries while running the 24-volt motor?
Or,
is that going to burn up the fish finder? Should I just invest in a
couple
of 6-volt lantern batteries instead?

One of the batteries is referenced to GROUND, the other is not.

If you connect your fish finder across the battery that is referenced to
GROUND, you should be fine. If you make the mistake of connecting across
the
*other* battery, what the fish finder "thinks" is GROUND will actually be
12
volts *above* GROUND, which sooner or later will be revealed to be A Bad
Thing...

/daytripper

On Tue, 8 Jun 2004 22:55:51 -0400, "Marty S." wrote:

I'm not sure about your answer, Daytripper. I don't have either battery
connected to ground as far as I know. The + terminal of one battery goes to
the motor, and the - terminal of the other battery goes to the motor, and
the other terminals are connected to each other so the battery is connected
in series.

Might help to draw this out.

A typical 12v wiring job on a boat with an electric starter (at least), some
part of the motor is connected to the negative pole of the 12v battery. That
would be the moral equivalent to "earth ground" on a boat.

The electronics are referenced to the same potential, and things like antenna
ground and lighting fixtures may be referenced to that same potential, as it
is the return path for all powered things on the boat.

Shifting that potential by connecting the negative pole of the original
battery to the positive pole of the first battery (and then connecting the
negative pole of the second battery to the negative terminal of the trolling
motor) runs a certain risk different current return paths at different
potentials coming in contact with each other. Ie: if the exterior of the
trolling motor is connected to its negative terminal, when the motor is in the
water there could be current flowing through the *boat* motor (which is
connected to the negative pole of the original battery).

That wouldn't be good, I suspect ;-)

/daytripper

Daytripper: I don't have two motors. This is just a small jon boat powered
by an 24-volt electric trolling motor with 2 batteries connected in series.

--
Marty S.
Baltimore, MD USA


"daytripper" wrote in message
...
On Tue, 8 Jun 2004 22:55:51 -0400, "Marty S." wrote:

I'm not sure about your answer, Daytripper. I don't have either battery
connected to ground as far as I know. The + terminal of one battery goes
to
the motor, and the - terminal of the other battery goes to the motor, and
the other terminals are connected to each other so the battery is
connected
in series.

Might help to draw this out.

A typical 12v wiring job on a boat with an electric starter (at least),
some
part of the motor is connected to the negative pole of the 12v battery.
That
would be the moral equivalent to "earth ground" on a boat.

The electronics are referenced to the same potential, and things like
antenna
ground and lighting fixtures may be referenced to that same potential, as
it
is the return path for all powered things on the boat.

Shifting that potential by connecting the negative pole of the original
battery to the positive pole of the first battery (and then connecting the
negative pole of the second battery to the negative terminal of the
trolling
motor) runs a certain risk different current return paths at different
potentials coming in contact with each other. Ie: if the exterior of the
trolling motor is connected to its negative terminal, when the motor is in
the
water there could be current flowing through the *boat* motor (which is
connected to the negative pole of the original battery).

That wouldn't be good, I suspect ;-)

/daytripper

Your fish finder will be fine across one of the batteries. If you're
hesitant, apply (or borrow) your voltmeter across either of the batteries.
You'll find it reads ... 12 volts.


"Marty S." wrote in message
...
I'm running 2 12-volt batteries running in series to power my 24-volt
electric motor in my jon boat (on an electric-only reservoir) and I want
to
run a fish finder. Here's my question -- can I safely run the fish finder
off of one of the 2 12-volt batteries while running the 24-volt motor?
Or,
is that going to burn up the fish finder? Should I just invest in a
couple
of 6-volt lantern batteries instead?

--
Marty S.
Baltimore, MD USA

I've checked the voltage and either battery by itself reads 12 volts when
hooked up in series, and they are 24 together. However, is there an issue
of amps or watts or current or whatever else flows in the wires? The fish
finder draws about 110 milliamps (whatever that is)... Will it burn out or
crack or implode or fizz out or whatever? (as you can tell, I didn't spend
a whole lot of time paying attention in 7th grade electrical shop)

--
Marty S.
Baltimore, MD USA


"Bowgus" wrote in message
. rogers.com...
Your fish finder will be fine across one of the batteries. If you're
hesitant, apply (or borrow) your voltmeter across either of the batteries.
You'll find it reads ... 12 volts.


"Marty S." wrote in message
...
I'm running 2 12-volt batteries running in series to power my 24-volt
electric motor in my jon boat (on an electric-only reservoir) and I want
to
run a fish finder. Here's my question -- can I safely run the fish
finder
off of one of the 2 12-volt batteries while running the 24-volt motor?
Or,
is that going to burn up the fish finder? Should I just invest in a
couple
of 6-volt lantern batteries instead?

--
Marty S.
Baltimore, MD USA

Marty S. wrote:
I've checked the voltage and either battery by itself reads 12 volts when
hooked up in series, and they are 24 together. However, is there an issue
of amps or watts or current or whatever else flows in the wires? The fish
finder draws about 110 milliamps (whatever that is)... Will it burn out or
crack or implode or fizz out or whatever? (as you can tell, I didn't spend
a whole lot of time paying attention in 7th grade electrical shop)


110 Milliamps (0.110 amps per hour current flow) is what your finder
draws at 12 volts. if you made the mistake and hooked it up to both
batteries (24 volts) then it would draw 210 milliamps, burning out your
finder, then increasing the amp draw even more as wire's insulation
melts, and wires short out to each other) . or at least blowing the fuze.
As long as your hooked to the Positive and negative of the same battery
you have nothing to worry about, your finder is wired up correctly, that
is if your circuit is not grounded to the boat, and all fish finders I
know of are not, they have a floating circuit (both Positive and
negative wires go to the finder)
--
Rodney Long,
Inventor of the Long Shot "WIGGLE" rig, SpecTastic Thread
Boomerang Fishing Pro. ,Stand Out Hooks ,Stand Out Lures,
Mojo's Rock Hopper & Rig Saver weights, Decoy Activator
and the EZKnot http://www.ezknot.com

In rec.boats Marty S. wrote:
: I've checked the voltage and either battery by itself reads 12 volts when
: hooked up in series, and they are 24 together. However, is there an issue
: of amps or watts or current or whatever else flows in the wires? The fish
: finder draws about 110 milliamps (whatever that is)... Will it burn out or
: crack or implode or fizz out or whatever? (as you can tell, I didn't spend
: a whole lot of time paying attention in 7th grade electrical shop)

Shouldn't be a problem connecting across one battery. Especially given
that the fish finder only draws 110 mA.

b.