Larry wrote:
jeff wrote in
:

1 kWh per day.
Supplying this with an inverter would take over 100 AmpHours.

1KWh at 13.8V = 72AH per day....1000/13.8V

Not much of a problem for a 330AH golf cart pair....


So your golf cart batteries put out 13.8 Volts under load? Are they
those new 7 cell batteries? And send me one of the 100% efficient
invertors.

And as always, you're missing the real points. The important issue is
not having a big enough bank to run for one day (unless that's all the
time you're away from the dock), its recharging the batteries.

And of course for the two systems I compared, for the needs of a
cruiser, a 10 cubic foot system that includes a large deep freeze and
runs on 60 Amp-hours a day is vastly superior to 5.7 foot fridge with
tiny semi-freezer that takes 100 Amp-hours. Whether its worth the 10X
(or more) price difference is academic.

On Sun, 20 Jul 2008 08:15:36 -0400, jeff wrote:

Bruce in Bangkok wrote:
On Sat, 19 Jul 2008 22:33:47 -0400, jeff wrote:

Bruce in Bangkok wrote:
Not to disparage anyone but have a look at the battery manufacturer's
specs and see whether they recommend that high a charging rate. I
suspect you'll see something like 10 - 15% of rated capacity.

That's what Trojan says for their wet cells, though I've done a lot of
charging at more like 18-20% will no ill affects. My first set did die
after 7 years (they might have gone another year or so if I had tended
to them better over a harsh winter), but frankly, they are the cheapest
part of the system.

For their gel and AGM batteries, they say 20%

From all I can read the rate of charge is determined more by what it
is doing to the electrolyte then anything else. If you read up on car
alternators you will read many references to "without excess water
loss". So, probably if your batteries aren't getting hot and aren't
gassing excessively the current is not excessive. I think I read
somewhere 120 degrees F was the hottest allowable.

But the point Larry keeps making, and every competent description I
have ever read about lead acid batteries emphasizes is that because
the process is a chemical process it takes some time to accomplish. No
matter how many amps of current you blast in there it still takes time
to convert the plate material back to it's original state.

Its certainly true that there are limits, and its especially true that
to achieve 100% takes a long time, but the empirical evidence remains:
good wet cells can be charged at about 20% of their capacity over the
range of 50% to 80% charge. In practice this means the typical 4 6-Volt
bank (450 AmpHours) can be given a useful charge in about an hour.



Try .http://www.batteryfaq.org/ for more information then you ever
wanted to know about batteries.

This says not to go over 25% for wet cells, a rate that Larry seems to
say is physically impossible. Sometimes my systems approach this level
briefly at startup, but generally I limit it to 20%, or 90 Amps. In
practice, most of the charging is between 75 and 85 Amps.


As I read Larry's post he is saying that if you dump a bunch of amps
into the battery only some of them actually charge the battery. the
rest turn into heat which is true.

Another site http://jgdarden.com/batteryfaq/carfaq9.htm recommends:

The BULK stage is where the charger current is constant and the
battery voltage increases, which is normally during the first 80% of
the recharge. Give the battery whatever current it will accept as long
as it does not exceed 25% of the 20 hour (expressed "C/20") ampere
hour (AH) capacity rating, 10% of the Reserve Capacity (RC) rating,
wet batteries do not exceed 125° F (51.5° C), and VRLA batteries do
not exceed 100° F (37.8° C).

which seems like a sensible recommendation. I recently read something
about batteries with very low impedance that can be charged at very
high amperage levels so obviously all batteries are not created
equally. But, what I do myself is one thing but what I recommend to
someone else is going to be pretty conservative, as above.


The writer sells various battery meters, combiners, regulators, etc.,
but his writing is impartial and very informative.


Bruce-in-Bangkok
(correct Address is bpaige125atgmaildotcom)

Bruce-in-Bangkok
(correct Address is bpaige125atgmaildotcom)

Bruce in Bangkok wrote:
On Sun, 20 Jul 2008 08:15:36 -0400, jeff wrote:

Bruce in Bangkok wrote:
On Sat, 19 Jul 2008 22:33:47 -0400, jeff wrote:

Bruce in Bangkok wrote:
Not to disparage anyone but have a look at the battery manufacturer's
specs and see whether they recommend that high a charging rate. I
suspect you'll see something like 10 - 15% of rated capacity.

That's what Trojan says for their wet cells, though I've done a lot of
charging at more like 18-20% will no ill affects. My first set did die
after 7 years (they might have gone another year or so if I had tended
to them better over a harsh winter), but frankly, they are the cheapest
part of the system.

For their gel and AGM batteries, they say 20%
From all I can read the rate of charge is determined more by what it
is doing to the electrolyte then anything else. If you read up on car
alternators you will read many references to "without excess water
loss". So, probably if your batteries aren't getting hot and aren't
gassing excessively the current is not excessive. I think I read
somewhere 120 degrees F was the hottest allowable.

But the point Larry keeps making, and every competent description I
have ever read about lead acid batteries emphasizes is that because
the process is a chemical process it takes some time to accomplish. No
matter how many amps of current you blast in there it still takes time
to convert the plate material back to it's original state.
Its certainly true that there are limits, and its especially true that
to achieve 100% takes a long time, but the empirical evidence remains:
good wet cells can be charged at about 20% of their capacity over the
range of 50% to 80% charge. In practice this means the typical 4 6-Volt
bank (450 AmpHours) can be given a useful charge in about an hour.


Try .http://www.batteryfaq.org/ for more information then you ever
wanted to know about batteries.
This says not to go over 25% for wet cells, a rate that Larry seems to
say is physically impossible. Sometimes my systems approach this level
briefly at startup, but generally I limit it to 20%, or 90 Amps. In
practice, most of the charging is between 75 and 85 Amps.


As I read Larry's post he is saying that if you dump a bunch of amps
into the battery only some of them actually charge the battery. the
rest turn into heat which is true.

Of course, its true of all processes. Nothing is 100% efficient. The
questions are, how efficient is it, and how quickly can you charge at
reasonable efficiency. Ranting in ALL CAPS that its physically
impossible because bad math proves it doesn't make Larry an expert.

So here's a quick calc: 90 Amps times 14 Volts times 13% (Trojan says
charge efficiency is 87%) yields 164 Watts of waste heat. Certainly in
an overly constrained space, this can add up, but its no more than a
table lamp or even a TV. Maybe when I have time I'll compute how
quickly the mass of the bank will heat up - I wouldn't be surprised if
an hour of charging is not really enough to heat to bank to critical levels.

On Sun, 20 Jul 2008 10:27:14 -0400, jeff wrote:

Bruce in Bangkok wrote:
On Sun, 20 Jul 2008 08:15:36 -0400, jeff wrote:

Bruce in Bangkok wrote:
On Sat, 19 Jul 2008 22:33:47 -0400, jeff wrote:

Bruce in Bangkok wrote:
Not to disparage anyone but have a look at the battery manufacturer's
specs and see whether they recommend that high a charging rate. I
suspect you'll see something like 10 - 15% of rated capacity.

That's what Trojan says for their wet cells, though I've done a lot of
charging at more like 18-20% will no ill affects. My first set did die
after 7 years (they might have gone another year or so if I had tended
to them better over a harsh winter), but frankly, they are the cheapest
part of the system.

For their gel and AGM batteries, they say 20%
From all I can read the rate of charge is determined more by what it
is doing to the electrolyte then anything else. If you read up on car
alternators you will read many references to "without excess water
loss". So, probably if your batteries aren't getting hot and aren't
gassing excessively the current is not excessive. I think I read
somewhere 120 degrees F was the hottest allowable.

But the point Larry keeps making, and every competent description I
have ever read about lead acid batteries emphasizes is that because
the process is a chemical process it takes some time to accomplish. No
matter how many amps of current you blast in there it still takes time
to convert the plate material back to it's original state.
Its certainly true that there are limits, and its especially true that
to achieve 100% takes a long time, but the empirical evidence remains:
good wet cells can be charged at about 20% of their capacity over the
range of 50% to 80% charge. In practice this means the typical 4 6-Volt
bank (450 AmpHours) can be given a useful charge in about an hour.


Try .http://www.batteryfaq.org/ for more information then you ever
wanted to know about batteries.
This says not to go over 25% for wet cells, a rate that Larry seems to
say is physically impossible. Sometimes my systems approach this level
briefly at startup, but generally I limit it to 20%, or 90 Amps. In
practice, most of the charging is between 75 and 85 Amps.


As I read Larry's post he is saying that if you dump a bunch of amps
into the battery only some of them actually charge the battery. the
rest turn into heat which is true.

Of course, its true of all processes. Nothing is 100% efficient. The
questions are, how efficient is it, and how quickly can you charge at
reasonable efficiency. Ranting in ALL CAPS that its physically
impossible because bad math proves it doesn't make Larry an expert.

So here's a quick calc: 90 Amps times 14 Volts times 13% (Trojan says
charge efficiency is 87%) yields 164 Watts of waste heat. Certainly in
an overly constrained space, this can add up, but its no more than a
table lamp or even a TV. Maybe when I have time I'll compute how
quickly the mass of the bank will heat up - I wouldn't be surprised if
an hour of charging is not really enough to heat to bank to critical levels.


Go to http://www.smartgauge.co.uk/index.html and read the technical
info (there are several sections 1,2,3) look for all the references to
"peukert". It is a bit more complicated then V * A.

But again, the manufacturers all seem to say that temperature is the
controlling factor, not amps, per se. As far as I can tell the
recommended amperages are there to restrict the temperature rise. The
number I have read is 120 deg. F max.


Bruce-in-Bangkok
(correct Address is bpaige125atgmaildotcom)

"Bruce in Bangkok" wrote in message
...
On Sat, 19 Jul 2008 23:19:52 -0700, "Capt. JG"
wrote:

"Larry" wrote in message
. ..
Bruce in Bangkok wrote in
:

Since here in Thailand, and probably all over the third world, they
are happily using R-12, and dumping it to atmosphere it probably goes
to prove that the Americans were responsible.



Not to mention the extensive air pollution controls on all those
thousands
of 2-stroke little trucks running old motor oil at 15:1 premix....

It's those damned Americans....every time. They love to be blamed.


So, we should just go for it? Just because someone else is doing something
wrong does not give us license to do something wrong.

Then what are you doing in Iraq?


Sorry the temptation overcame me.


It's a great temptation to lump all Americans with Bu****, so I forgive you!

I find it ironic.. the "surge" is working by driving the terrorists to
Afganistan. If we had gone after them in that place first... sigh, you're
right it's tempting.


--
"j" ganz @@
www.sailnow.com

On Sun, 20 Jul 2008 03:14:32 +0000, in message

Larry wrote:

I don't understand how they get 274 watts of cooling with only 168 watts
input. Must be physics magic!

It's not magic. You should review your thermodynamics for cooling
cycles. The only power input required for cooling is to overcome
inefficiencies in heat transport, hence coefficients of performance
(not efficiencies) considerably larger than 1.

A COP of about 1.8 suggests a bad design / installation.

If you don't understand it, you should either ask for advice or read
the specs and instructions.

Ryk

On Sat, 19 Jul 2008 09:51:08 +1000, in message

Herodotus wrote:

Hi Ryk,
Thanks for this as I don't know how real the company's power usage
figures are and at what outside temperature they are quoted for.

It really depends on your cool space volume and insulation, so they
can't quote figures for your boat. I got a huge improvement with an
insulation upgrade a few years ago. All low tech, just new foam in
place of the stuff that was rotting.

I note that the one I am looking at states that it is for a
refridgerator, not a freezer. However an optional extra is an ice
making tray. Does this mean that one could have a small freezer
compartment overflowing to a larger fridge one. A freezer would be
great but not vital. Iced water would be nice though.

I don't know. My holding plate gets cold enough to make a thick layer
of frost, which later melts. I don't know if I would trust it to keep
anything frozen, since the ASU controller aims to keep the fridge cool
by letting the holding plate thaw when the engine isn't running.

For fridge management, I put fresh meat and some beverages really
close to the plate.

Ryk

On Sun, 20 Jul 2008 16:04:51 +0700, Bruce in Bangkok
wrote:

On Sun, 20 Jul 2008 15:44:25 +1000, Herodotus
wrote:

On Sat, 19 Jul 2008 21:55:09 +0000, Larry wrote:

" wrote in news:b2f93b8e-4554-434c-
:

What's the down side?



Oil company profits.....for my president's family.

Careful Larry,

That sounds completely un-American to me.

Be very careful lest you end up in Cuba - ouside of Constitutional
protection.


But I hear it is real cheap and a lot of girls. A spanish speaking
Thailand?

Bruce-in-Bangkok
(correct Address is bpaige125atgmaildotcom)

Perhaps but the part of Cuba I was referring to has barbed wire,
waterboarding and US troops. It's just that I can't spell it. I
suppose they may have semi-naked Cuban women parading outside the
wire. Like waterboarding, it may not be considered torture.

I am following the battery/fridge thread with avidity.

Looking forward to the warmth in a few days. It is damned cold here.
The Pope flies home today so the masses of Catholic pilgrims will be
gone soon and Sydney will be back to normal. No more singing euphoric
youngsters and flags in your face walking two abreast in long lines
down the footpath (sidewalk to the barbarians) and blocking it in
groups at times forcing a detour onto the roadway. We will revert to
the sullen, untrusting and hardened "I'll get you before you get me"
and "I paid for this seat on the bus/train/ferry and I'm not going to
stand up for anyone regardless of age and infirmity" citizenry once
more.

cheers
Peter

On Sun, 20 Jul 2008 16:42:36 +0700, Bruce in Bangkok
wrote:

On Sat, 19 Jul 2008 23:19:52 -0700, "Capt. JG"
wrote:

"Larry" wrote in message
. ..
Bruce in Bangkok wrote in
:

Since here in Thailand, and probably all over the third world, they
are happily using R-12, and dumping it to atmosphere it probably goes
to prove that the Americans were responsible.



Not to mention the extensive air pollution controls on all those thousands
of 2-stroke little trucks running old motor oil at 15:1 premix....

It's those damned Americans....every time. They love to be blamed.


So, we should just go for it? Just because someone else is doing something
wrong does not give us license to do something wrong.

Then what are you doing in Iraq?


Sorry the temptation overcame me.

Bruce-in-Bangkok
(correct Address is bpaige125atgmaildotcom)

Bruce,

I would have liked to have said that but was mortally afraid of a
tirade of accusations of anti-Americanism and "You hate us don't you"
and "You are jealous and angry that you can't live here" - so I
refrained from commenting.

Peter

On Sun, 20 Jul 2008 09:42:41 -0700, "Capt. JG"
wrote:

"Bruce in Bangkok" wrote in message
.. .
On Sat, 19 Jul 2008 23:19:52 -0700, "Capt. JG"
wrote:

"Larry" wrote in message
...
Bruce in Bangkok wrote in
:

Since here in Thailand, and probably all over the third world, they
are happily using R-12, and dumping it to atmosphere it probably goes
to prove that the Americans were responsible.



Not to mention the extensive air pollution controls on all those
thousands
of 2-stroke little trucks running old motor oil at 15:1 premix....

It's those damned Americans....every time. They love to be blamed.


So, we should just go for it? Just because someone else is doing something
wrong does not give us license to do something wrong.

Then what are you doing in Iraq?


Sorry the temptation overcame me.


It's a great temptation to lump all Americans with Bu****, so I forgive you!

I find it ironic.. the "surge" is working by driving the terrorists to
Afganistan. If we had gone after them in that place first... sigh, you're
right it's tempting.

I must have missed something.

Have they found oil in Afghanistan?

I for one am interested in the outcome as historically nobody from
outside has managed to completely conquer and rule that country from
Alexander, the British, to the Russians. If you have ever experienced
the tribal nature of most of its citizens you would understand more
the difficulties. Xenophobia is in the genes.

Peter