I've never known an electricain that knew much about DC. Most deal with
nothing but AC and then only know about standard codes and
techniques related to household and industrial wiring. You would
get better mileage claiming you are a neurosurgeon, Neal.


"Capt. Neal®" wrote in message
...

"Me" wrote in message
...
In article ,
Capt. Neal® wrote:

I disagree. Two 12v batteries in series to make a 24v battery will
self-level
with respect to charge.

They will self level even if one is tapped to run a VHF. No harm will
come
to either battery. Voltage can be likened to pressure.

I hope this helps.

CN

bullcrap.... Better to leave the Blackgang stuff to the engineers that
know what they are talking about......

Me


I'm an electrician. Don't insult me with this engineer crap. I know how
batteries work and I know circuits - particularly DC circuits.

You idiots are only correct provided there is no circuit to which the
two 12v batteries in series are connected. In any yacht I've ever
been on the batteries are part of a circuit of there would be no
use to have them aboard other than as ballast.

In Nigel's case, tapping off one of two batteries connected in series in
a circuit to run his VHF will not cause only the tapped battery to
discharge
as the voltage in the circuit will be lowered and not just the voltage
in the tapped battery.

Only if the two batteries were disconnected from the circuit would
the tapped battery discharge more than the untapped battery.

C'mon, folks, it doesn't take a rocket scientist to figure something
this basic out.

CN

On Sun, 17 Apr 2005 19:08:09 -0400, Capt. Neal®
wrote:


"Meindert Sprang" wrote in message ...
"Glenn Ashmore" wrote in message
news:cbu8e.7195$Z73.4465@lakeread04...
Why all this ranting over a proven fact that drawing 12V off of one
battery
of a 24V bank is not a good idea? A 40 amp 24/12 DC/DC converter capable
of running all the electronics on the boat can be bought for the price of
a
couple of golf cart batteries.

This is nonsense!

I agree with you completely, Glenn. It's just that I cannot stand those
people who claim to be in the know, are misinforming people who aren't.

Meindert


You don't know squat about batteries in a circuit, Mr. Sprang. You are
the one doing the misinforming.

Read my other posts and do something about your ignorance.
Read this one, too. Perhaps if you read the truth three or
four times it just might sink in.

Nigel doesn't need anything but a couple of wires tapped off one
of the batteries in his series circuit and as long as a circuit is maintained
the two batteries will take and maintain an equal charge, irregardless
of the tap. It's only when the two batteries are isolated from the circuit
by a switch of some sort that the tapped battery will discharge and
the untapped battery will not be affected. Unless there is a circuit
there is no such thing as batteries connected in series. Connected in
a series implies or necessitates a circuit.

You can line up 20 flashlight D cells end to end and say they are connected
in series but until you complete a circuit they remain separate and distinct
cells. If you tap off the one in the center it will discharge and all the
others will not be affected but as soon as you connect them to a circuit
the discharged battery (ni-cad in this case) will become charged up at
the expense of the others until its voltage is raised and the others 'voltage
is lowered proportionally.

I hope this simple example will reduce your fogged thinking.

CN



I realize we are dealing with someone here that just wants to make an
argument and has no understanding of the subject at hand.
But perhaps it has some entertainment value.

Just so those that really want to know don't go away with the wrong
idea of how things work, maybe the good "Capn" would like to explain
how an individual cell in a battery that has been discharged is going
to be charged up by the other cells in the battery by merely placing a
load on the whole battery?

That individual discharged cell will be receiving reverse polarity
charge from the other cells in the circuit.

Of course maybe the "Capn" has some sort of magic battery in his boat.

Regards
Gary

"Nigel" wrote in message
...
I have a 24v electrical set up on my boat, but need a 12v supply for my
VHF
(amongst other things). Is there any reason why I can't just run a 12v
supply from just one of a pair of batteries, or do I need to use a 24v/12v
converter. I release this will draw charge from just one battery , but
won't
the other just top it up and there by drain them both equally
Thanks


At least everyone seems to agree that the problem (non existing according to
some people) is in the re-charging, not in the tapping off of the 12V.
It's interesting why so many people got it wrong. Perhaps it is because
they wrongly use the analogy with water. A water-flow through 2 unequally
filled reservoirs in series will cause the reservoirs to level, but not an
electric current through batteries. The total current has to flow through
both batteries. The difference with the example of the water reservoirs is
that the current itself does not charge the batteries, like the water does
to the reservoirs. It is the chemical EFFECT that the electric current has
on the batteries that charges them. The two unequally charged batteries have
different resistances and as they are in series they form a voltage divider.
During charging, the charger's voltage regulator senses the TOTAL Voltage of
the two batteries is series and adjusts the current to keep this at say 28.8
Volts during the absorbtion stage. The battery with the lower charge may be
charged with 14.2 Volts and the untapped one with 14.6 Volts. The latter
will gass and suffer and eventually fail, if this mistreatment takes place
on a regular basis.
During gassing, the full battery's Voltage will still rise, but slower than
the battery with the lesser charge.
This means that the lower battery will eventually reach near full charge,
but it will take long and at a great cost to the gassing battery.
To prevent overcharging and gassing of one battery, the charger should look
at the Voltage x 2 to of the higher Voltage battery. This can be achieved by
sensing only the untapped battery and using a 2x Voltage multiplier circuit.
By connecting the sense wire of the voltage regulator to this circuit, a
simple safety mechanism is built. Absorbtion charging will stop when this
battery reaches 14.4 Volts. It will protect the untapped (higher V) battery,
but it will take a long time for the tapped battery to reach near-full
charge state, as the full battery "puts the brake on". This not fully
charged state is less damaging than the gassing and is acceptable.
One way to compensate for this would be to connect a 12V solar panel to this
battery to top it up to full charge when the boat is not being used.
Wout

On Mon, 18 Apr 2005 14:13:29 +1200, "Wout B"
wrote:


"Nigel" wrote in message
.. .
I have a 24v electrical set up on my boat, but need a 12v supply for my
VHF
(amongst other things). Is there any reason why I can't just run a 12v
supply from just one of a pair of batteries, or do I need to use a 24v/12v
converter. I release this will draw charge from just one battery , but
won't
the other just top it up and there by drain them both equally
Thanks


At least everyone seems to agree that the problem (non existing according to
some people) is in the re-charging, not in the tapping off of the 12V.
It's interesting why so many people got it wrong. Perhaps it is because
they wrongly use the analogy with water. A water-flow through 2 unequally
filled reservoirs in series will cause the reservoirs to level, but not an
electric current through batteries. The total current has to flow through
both batteries. The difference with the example of the water reservoirs is
that the current itself does not charge the batteries, like the water does
to the reservoirs. It is the chemical EFFECT that the electric current has
on the batteries that charges them. The two unequally charged batteries have
different resistances and as they are in series they form a voltage divider.
During charging, the charger's voltage regulator senses the TOTAL Voltage of
the two batteries is series and adjusts the current to keep this at say 28.8
Volts during the absorbtion stage. The battery with the lower charge may be
charged with 14.2 Volts and the untapped one with 14.6 Volts. The latter
will gass and suffer and eventually fail, if this mistreatment takes place
on a regular basis.
During gassing, the full battery's Voltage will still rise, but slower than
the battery with the lesser charge.
This means that the lower battery will eventually reach near full charge,
but it will take long and at a great cost to the gassing battery.
To prevent overcharging and gassing of one battery, the charger should look
at the Voltage x 2 to of the higher Voltage battery. This can be achieved by
sensing only the untapped battery and using a 2x Voltage multiplier circuit.
By connecting the sense wire of the voltage regulator to this circuit, a
simple safety mechanism is built. Absorbtion charging will stop when this
battery reaches 14.4 Volts. It will protect the untapped (higher V) battery,
but it will take a long time for the tapped battery to reach near-full
charge state, as the full battery "puts the brake on". This not fully
charged state is less damaging than the gassing and is acceptable.
One way to compensate for this would be to connect a 12V solar panel to this
battery to top it up to full charge when the boat is not being used.
Wout



Good explanation. As an added note,
not fully charging a battery is less damaging than overcharging but:

If just sensing the "untapped" battery and the charger shuts down,
goes into the float mode because that battery is fully charged, then
the "tapped" battery will never get a full charge. A battery that
never gets a full charge will sulfate and have a shorter life because
of it.
There is no way to win short of having individual chargers for each
battery. Or don't tap the battery bank.

Regards
Gary

"Gary Schafer" wrote in message
...
On Mon, 18 Apr 2005 14:13:29 +1200, "Wout B"
wrote:


"Nigel" wrote in message
.. .
I have a 24v electrical set up on my boat, but need a 12v supply for my
VHF
(amongst other things). Is there any reason why I can't just run a 12v
supply from just one of a pair of batteries, or do I need to use a
24v/12v
converter. I release this will draw charge from just one battery , but
won't
the other just top it up and there by drain them both equally
Thanks


At least everyone seems to agree that the problem (non existing according
to
some people) is in the re-charging, not in the tapping off of the 12V.
It's interesting why so many people got it wrong. Perhaps it is because
they wrongly use the analogy with water. A water-flow through 2 unequally
filled reservoirs in series will cause the reservoirs to level, but not
an
electric current through batteries. The total current has to flow through
both batteries. The difference with the example of the water reservoirs
is
that the current itself does not charge the batteries, like the water
does
to the reservoirs. It is the chemical EFFECT that the electric current
has
on the batteries that charges them. The two unequally charged batteries
have
different resistances and as they are in series they form a voltage
divider.
During charging, the charger's voltage regulator senses the TOTAL Voltage
of
the two batteries is series and adjusts the current to keep this at say
28.8
Volts during the absorbtion stage. The battery with the lower charge may
be
charged with 14.2 Volts and the untapped one with 14.6 Volts. The latter
will gass and suffer and eventually fail, if this mistreatment takes
place
on a regular basis.
During gassing, the full battery's Voltage will still rise, but slower
than
the battery with the lesser charge.
This means that the lower battery will eventually reach near full charge,
but it will take long and at a great cost to the gassing battery.
To prevent overcharging and gassing of one battery, the charger should
look
at the Voltage x 2 to of the higher Voltage battery. This can be achieved
by
sensing only the untapped battery and using a 2x Voltage multiplier
circuit.
By connecting the sense wire of the voltage regulator to this circuit, a
simple safety mechanism is built. Absorbtion charging will stop when this
battery reaches 14.4 Volts. It will protect the untapped (higher V)
battery,
but it will take a long time for the tapped battery to reach near-full
charge state, as the full battery "puts the brake on". This not fully
charged state is less damaging than the gassing and is acceptable.
One way to compensate for this would be to connect a 12V solar panel to
this
battery to top it up to full charge when the boat is not being used.
Wout



Good explanation. As an added note,
not fully charging a battery is less damaging than overcharging but:

If just sensing the "untapped" battery and the charger shuts down,
goes into the float mode because that battery is fully charged, then
the "tapped" battery will never get a full charge. A battery that
never gets a full charge will sulfate and have a shorter life because
of it.
There is no way to win short of having individual chargers for each
battery. Or don't tap the battery bank.

Regards
Gary

Gary,
Going too early into float-mode is a general problem with chargers. I've
"doctored" my smart 3-stage alternator V-reg to prolongue absorption. If
the batteries are not all that new anymore the V- level jumps up very
quickly. Timed absorption stage with adjustable time is ideal, because the
age and state of the batteries can be compensated for. In my opinion,
provided that the gassing is prevented as described and provided that the
tapped battery is regularly brought up to full charge in some way, the
tapping is O.K., if it is only for electronics. Maybe install a simple
changeover switch to tap the batteries in turn. Very important is of course,
like someone else mentioned before, that the electronics that are run this
way have an isolated -wire, not connected to the 24V system's ground.
Regards,
Wout





Maybe the batteries need replacement a year or so earlier, but I think it
will work out cheaper. Many people leave their boats on the moorings for
weeks with half-charged batteries and they still seem to get years of use
out of them. A bit of "tapping", wisely done, A cheap solution would also
be to install a changeover switch, to tap the batteries in turn, but the
gassing-prevention has to be number 1.

"Capt. Neal®" wrote in message
...
Wrong, wrong, wrong, wrong, wrong, wrong and incorrect!
How can some people's minds be so ineffective at thinking?

I know it is pointless to argue with you but:

Perhaps you ******s would understand it better using flashlight D cells
as an example. Take one D cell that is half charged (Ni-Cad) and put it
into
a two-cell flashlight in the company of another NI-Cad) D cell that is
fully
charged and turn on the switch. The bulb will light and current will
pass through the circuit. As well as working to light the bulb, the
fully-charged cell will discharge into the half charge cell until
the voltage in both cells equalizes.

Perhaps you could try to envision in which direction current flows through
the empty cell in this example and next, try to envision in which direction
current flows when *charging* a cell. Or even better: try this example for
yourself.

I hope this helps.

Certainly not.

Meindert

In article ,
Capt. Neal® wrote:

I'm an electrician. Don't insult me with this engineer crap. I know how
batteries work and I know circuits - particularly DC circuits.

You idiots are only correct provided there is no circuit to which the
two 12v batteries in series are connected. In any yacht I've ever
been on the batteries are part of a circuit of there would be no
use to have them aboard other than as ballast.

In Nigel's case, tapping off one of two batteries connected in series in
a circuit to run his VHF will not cause only the tapped battery to discharge
as the voltage in the circuit will be lowered and not just the voltage
in the tapped battery.

Only if the two batteries were disconnected from the circuit would
the tapped battery discharge more than the untapped battery.

C'mon, folks, it doesn't take a rocket scientist to figure something
this basic out.

CN

Like I stated before, if you paid any money for your electrical
education, you certainly should go back and ask for a refund,
because you didn't learn anything in DC Class......


Me

In article ,
Capt. Neal® wrote:

You don't know squat about batteries in a circuit, Mr. Sprang. You are
the one doing the misinforming.

Read my other posts and do something about your ignorance.
Read this one, too. Perhaps if you read the truth three or
four times it just might sink in.

Nigel doesn't need anything but a couple of wires tapped off one
of the batteries in his series circuit and as long as a circuit is maintained
the two batteries will take and maintain an equal charge, irregardless
of the tap. It's only when the two batteries are isolated from the circuit
by a switch of some sort that the tapped battery will discharge and
the untapped battery will not be affected. Unless there is a circuit
there is no such thing as batteries connected in series. Connected in
a series implies or necessitates a circuit.

You can line up 20 flashlight D cells end to end and say they are connected
in series but until you complete a circuit they remain separate and distinct
cells. If you tap off the one in the center it will discharge and all the
others will not be affected but as soon as you connect them to a circuit
the discharged battery (ni-cad in this case) will become charged up at
the expense of the others until its voltage is raised and the others 'voltage
is lowered proportionally.

I hope this simple example will reduce your fogged thinking.

CN

and the Dufus chimes in again, with more off the wall BS.....


Me

In article ,
Gary Schafer wrote:

Of course maybe the "Capn" has some sort of magic battery in his boat.

Regards
Gary

The only thing Capt. Neal has on his boat is a lot of "Magic smoke"
that escaped his DC electrical Panel......


Me

"Me" wrote in message ...
In article ,
Capt. Neal® wrote:

You don't know squat about batteries in a circuit, Mr. Sprang. You are
the one doing the misinforming.

Read my other posts and do something about your ignorance.
Read this one, too. Perhaps if you read the truth three or
four times it just might sink in.

Nigel doesn't need anything but a couple of wires tapped off one
of the batteries in his series circuit and as long as a circuit is maintained
the two batteries will take and maintain an equal charge, irregardless
of the tap. It's only when the two batteries are isolated from the circuit
by a switch of some sort that the tapped battery will discharge and
the untapped battery will not be affected. Unless there is a circuit
there is no such thing as batteries connected in series. Connected in
a series implies or necessitates a circuit.

You can line up 20 flashlight D cells end to end and say they are connected
in series but until you complete a circuit they remain separate and distinct
cells. If you tap off the one in the center it will discharge and all the
others will not be affected but as soon as you connect them to a circuit
the discharged battery (ni-cad in this case) will become charged up at
the expense of the others until its voltage is raised and the others 'voltage
is lowered proportionally.

I hope this simple example will reduce your fogged thinking.

CN

and the Dufus chimes in again, with more off the wall BS.....


Me


Why not refute my example instead of calling me names.?

What's that you say? You can't refute the valid example? Oh, I see . . .

CN