Posted by *Ron Rosenfeld* on July 26, 2008, 1:57 am

On Fri, 25 Jul 2008 17:02:58 -0700 (PDT), bealiba@gmail.com wrote:

*>B7 specifies a battery. I did not specify a battery.*

*>B7 specifies a battery. I did not specify a battery.*

*>B7 specifies a battery. I did not specify a battery.*

*>B7 specifies a battery. I did not specify a battery.*

Oh, my. I must be suitably chastised by your irrelevant piffle.

There's no need, George, to keep advertising your ignorance and

shortcomings.

We are well aware that you did not, cannot, and will not specify a real

battery.

We are also well aware that you will not accept a battery that has ratings

that EXCEED those you published for this system.

There is no real battery that will meet YOUR design requirements and will

work for the OP's system.

What George wrote about battery requirements for the OP's system:

*>>*

*>> B2 Maximum allowable depth of discharge = 70%*

*>> B13 Capacity of battery bank at 100 hr rate (B12 x B10) = 180*

*>> C4 Battery efficiency = 90%*

This self-styled solar design consultant cannot designate a real battery

that meets the requirements HE entered into HIS spreadsheet and will work

in the OP's system!

He also cannot designate a real panel array that meets the design

requirements HE entered into HIS spreadsheet and commented about:

What George wrote about panels for the OP's system:

*>> C8 Selected module I at 14 volts at NOCT 2.94A*

*>> C13 Number of parallel strings of modules (C5 / C12) = 10.3*

*>>*

*>> 14 volts is the test standard at 25C. 17 volts is what the produces*

*>> when not connected to a load.*

Rather than admit that his third design is as flawed as his first two

attempts, he continues to blather away, hoping against hope that someone

might think he knows something about the subject.

--ron

Posted by *bealiba* on July 26, 2008, 5:41 am

*> On Fri, 25 Jul 2008 17:02:58 -0700 (PDT), beal...@gmail.com wrote:*

*> >B7 specifies a battery. I did not specify a battery.*

*> >B7 specifies a battery. I did not specify a battery.*

*> >B7 specifies a battery. I did not specify a battery.*

*> >B7 specifies a battery. I did not specify a battery.*

*> Oh, my. I must be suitably chastised by your irrelevant piffle.*

*> There's no need, George, to keep advertising your ignorance and*

*> shortcomings.*

*> We are well aware that you did not, cannot, and will not specify a real*

*> battery.*

Ah, now Tweedledee admits that I did not, in fact, specify a battery.

*> We are also well aware that you will not accept a battery that has ratings*

*> that EXCEED those you published for this system.*

Now that is a lie. The 180Ah in the formula is the minimum battery

capacity only.

*> There is no real battery that will meet YOUR design requirements and will*

*> work for the OP's system.*

Battery Energy 2AS1100 would surely do the job, although many would

consider them to be a bit of over kill.

*> What George wrote about battery requirements for the OP's system:*

*> >> B2 Maximum allowable depth of discharge = 70%*

*> >> B13 Capacity of battery bank at 100 hr rate (B12 x B10) = 180*

*> >> C4 Battery efficiency = 90%*

My, you really can't come to terms with user input can you. Pick a

battery, put the specs in. Oh yes, and learn the difference between

Maximum DOD and Daily DOD.

*> This self-styled solar design consultant cannot designate a real battery*

*> that meets the requirements HE entered into HIS spreadsheet and will work*

*> in the OP's system!*

B2, shows what sort of information is required. 70% is an acceptable

Maximum DOD for almost any deep cycle battery.

You should not change the calculation at B13 but you will need to

specify the discharge rate.

C4, I have used 90% simply because it works, but there is no reason

why you cannot change it. It is after all a point where the user need

to supply a number.

*> He also cannot designate a real panel array that meets the design*

*> requirements HE entered into HIS spreadsheet and commented about:*

As with the batteries I have not specified a panel.

*> What George wrote about panels for the OP's system:*

*> >> C8 Selected module I at 14 volts at NOCT 2.94A*

*> >> C13 Number of parallel strings of modules (C5 / C12) = 10.3*

C8 shows what sort of information is required

*> >> 14 volts is the test standard at 25C. 17 volts is what the produces*

*> >> when not connected to a load.*

True when the formula was written. This formula has been around for at

least 30 years and perhaps even longer.

*> Rather than admit that his third design is as flawed as his first two*

*> attempts, he continues to blather away, hoping against hope that someone*

*> might think he knows something about the subject.*

Notice that while words flow like water from Tweedledee's mouth,

actual maths are nonexistent in any of his posts.

Posted by *Ron Rosenfeld* on July 26, 2008, 2:00 pm

On Fri, 25 Jul 2008 22:41:17 -0700 (PDT), bealiba@gmail.com wrote:

*>> On Fri, 25 Jul 2008 17:02:58 -0700 (PDT), beal...@gmail.com wrote:*

*>> >B7 specifies a battery. I did not specify a battery.*

*>> >B7 specifies a battery. I did not specify a battery.*

*>> >B7 specifies a battery. I did not specify a battery.*

*>> >B7 specifies a battery. I did not specify a battery.*

*>>*

*>> Oh, my. I must be suitably chastised by your irrelevant piffle.*

*>>*

*>> There's no need, George, to keep advertising your ignorance and*

*>> shortcomings.*

*>>*

*>> We are well aware that you did not, cannot, and will not specify a real*

*>> battery.*

*>The 180Ah in the formula is the minimum battery capacity only.*

*>>*

*>> There is no real battery that will meet YOUR design requirements and will*

*>> work for the OP's system.*

*>Battery Energy 2AS1100 would surely do the job, although many would*

*>consider them to be a bit of over kill.*

Look at George waffle.

George sets a requirement for a 180AH battery at the 100 hr rate;

George claims that is a minimum requirement;

And when George finally specifies a real battery, comes up with one that

has a capacity at the 100 hr rate of over 1000Ah!!! (1047Ah,

approximately)

His minimum battery capacity was grossly inadequate!!

*>>*

*>> What George wrote about battery requirements for the OP's system:*

*>>*

*>>*

*>>*

*>> >> B2 Maximum allowable depth of discharge = 70%*

*>> >> B13 Capacity of battery bank at 100 hr rate (B12 x B10) = 180*

*>> >> C4 Battery efficiency = 90%*

*>My, you really can't come to terms with user input can you. Pick a*

*>battery, put the specs in. *

YOU were the user who put in the specs that resulted in these requirments!!

*>>*

*>> This self-styled solar design consultant cannot designate a real battery*

*>> that meets the requirements HE entered into HIS spreadsheet and will work*

*>> in the OP's system!*

*>B2, shows what sort of information is required. 70% is an acceptable*

*>Maximum DOD for almost any deep cycle battery.*

*>You should not change the calculation at B13 but you will need to*

*>specify the discharge rate.*

*>C4, I have used 90% simply because it works, but there is no reason*

*>why you cannot change it. It is after all a point where the user need*

*>to supply a number.*

*>>*

*>> He also cannot designate a real panel array that meets the design*

*>> requirements HE entered into HIS spreadsheet and commented about:*

*>As with the batteries I have not specified a panel.*

*>>*

*>> What George wrote about panels for the OP's system:*

*>>*

*>> >> C8 Selected module I at 14 volts at NOCT 2.94A*

*>> >> C13 Number of parallel strings of modules (C5 / C12) = 10.3*

*>C8 shows what sort of information is required*

*>>*

*>> >> 14 volts is the test standard at 25C. 17 volts is what the produces*

*>> >> when not connected to a load.*

*>True when the formula was written. This formula has been around for at*

*>least 30 years and perhaps even longer.*

Oh, this must be the GTC (Ghio Test Condition) imaginary standard that's 30

years old. Battery chemistry must have changed in the past 30 years since

today we need higher voltages to work in a nominal 12 volt system.

*>>*

*>> Rather than admit that his third design is as flawed as his first two*

*>> attempts, he continues to blather away, hoping against hope that someone*

*>> might think he knows something about the subject.*

*>Notice that while words flow like water from Tweedledee's mouth,*

*>actual maths are nonexistent in any of his posts.*

Note that the only battery George has specified exceeds his minimum

requirements by a factor of almost six (6)!!!

He has to exceed his *minimum* requirements by some huge amount in order to

get his system to work! (That's not in his spreadsheet though). No wonder

he doesn't tell us this!

Since he seems to like the Suncycle series of Battery Energy brand of

batteries, what happens if we use a battery that actually MEETS *his*

minimum specifications:

For example, the 6AS190:

*> GG spec: B13 Capacity of battery bank at *100* hr rate (B12 x B10) = *180**

Mfg spec for 6AS190: Capacity at *100* hr rate = *184*

Going back to the OP's requirements to run a 2500W pump for 30 minutes, we

can see by simple mathematics that this battery, which MEETS George's

"minimum" requirements, cannot work.

Again, according to George's specifications:

A4 Inverter Efficiency = 85%

A7 System Voltage = 12

So, for the 1/2 hr, our 2500W pump causes the inverter to draw current at a

rate of: 2500/0.85/12 = 245A

The 6AS190, which MEETS George's minimum requirements, when subjected to

this current draw, has a capacity of well under 50AH. As a matter of fact,

examining the capacity current curve published by the manufacturer suggests

that the capacity, at this current draw, is no more than 30AH, and likely a

good deal less.

In other words, a battery that actually MEETS *George's* minimun

requirements will run the pump for 30/245*60 = 7 minutes at the very most.

He needs to specify a battery that is almost six (6) times his minimum

requirement of 180Ah at the 100hr rate to get a functioning system.

Wow, what a deeziner!! Or, as Nick Pine would have said, "What a nitwit!"

--ron

Posted by *bealiba* on July 26, 2008, 2:53 pm

*> On Fri, 25 Jul 2008 22:41:17 -0700 (PDT), beal...@gmail.com wrote:*

*> >> On Fri, 25 Jul 2008 17:02:58 -0700 (PDT), beal...@gmail.com wrote:*

*> >> >B7 specifies a battery. I did not specify a battery.*

*> >> >B7 specifies a battery. I did not specify a battery.*

*> >> >B7 specifies a battery. I did not specify a battery.*

*> >> >B7 specifies a battery. I did not specify a battery.*

*> >> Oh, my. I must be suitably chastised by your irrelevant piffle.*

*> >> There's no need, George, to keep advertising your ignorance and*

*> >> shortcomings.*

*> >> We are well aware that you did not, cannot, and will not specify a real*

*> >> battery.*

*> >The 180Ah in the formula is the minimum battery capacity only.*

*> >> There is no real battery that will meet YOUR design requirements and will*

*> >> work for the OP's system.*

*> >Battery Energy 2AS1100 would surely do the job, although many would*

*> >consider them to be a bit of over kill.*

*> Look at George waffle.*

*> George sets a requirement for a 180AH battery at the 100 hr rate;*

I did not set the requirement, 180Ah is the minimum required capacity.

*> George claims that is a minimum requirement;*

*> And when George finally specifies a real battery, comes up with one that*

*> has a capacity at the 100 hr rate of over 1000Ah!!! (1047Ah,*

*> approximately)*

I did not specify that that battery be used and in fact pointed out

that while it would work it is well over that required.

*> His minimum battery capacity was grossly inadequate!!*

A the rate of 0.5 hours 180 Ah is good enough.

*> >> What George wrote about battery requirements for the OP's system:*

*> >> >> B2 Maximum allowable depth of discharge = 70%*

*> >> >> B13 Capacity of battery bank at 100 hr rate (B12 x B10) = 180*

*> >> >> C4 Battery efficiency = 90%*

*> >My, you really can't come to terms with user input can you. Pick a*

*> >battery, put the specs in.*

*> YOU were the user who put in the specs that resulted in these requirments!!*

I did not specify anything beyond the minimum capacity, that being

calculated from known daily requirement .

*> >> This self-styled solar design consultant cannot designate a real battery*

*> >> that meets the requirements HE entered into HIS spreadsheet and will work*

*> >> in the OP's system!*

*> >B2, shows what sort of information is required. 70% is an acceptable*

*> >Maximum DOD for almost any deep cycle battery.*

*> >You should not change the calculation at B13 but you will need to*

*> >specify the discharge rate.*

*> >C4, I have used 90% simply because it works, but there is no reason*

*> >why you cannot change it. It is after all a point where the user need*

*> >to supply a number.*

*> >> He also cannot designate a real panel array that meets the design*

*> >> requirements HE entered into HIS spreadsheet and commented about:*

*> >As with the batteries I have not specified a panel.*

*> >> What George wrote about panels for the OP's system:*

*> >> >> C8 Selected module I at 14 volts at NOCT 2.94A*

*> >> >> C13 Number of parallel strings of modules (C5 / C12) = 10.3*

*> >C8 shows what sort of information is required*

*> >> >> 14 volts is the test standard at 25C. 17 volts is what the produces*

*> >> >> when not connected to a load.*

*> >True when the formula was written. This formula has been around for at*

*> >least 30 years and perhaps even longer.*

*> Oh, this must be the GTC (Ghio Test Condition) imaginary standard that's 30*

*> years old. Battery chemistry must have changed in the past 30 years since*

*> today we need higher voltages to work in a nominal 12 volt system.*

So change the specs. That what user input means.

*> >> Rather than admit that his third design is as flawed as his first two*

*> >> attempts, he continues to blather away, hoping against hope that someone*

*> >> might think he knows something about the subject.*

*> >Notice that while words flow like water from Tweedledee's mouth,*

*> >actual maths are nonexistent in any of his posts.*

*> Note that the only battery George has specified exceeds his minimum*

*> requirements by a factor of almost six (6)!!!*

Yeah, good isn't it.

*> He has to exceed his *minimum* requirements by some huge amount in order to*

*> get his system to work! (That's not in his spreadsheet though). No wonder*

*> he doesn't tell us this!*

No you claimed that I was afraid that a larger battery would not work,

as you can see, I'm not. It does.

*> Since he seems to like the Suncycle series of Battery Energy brand of*

*> batteries, what happens if we use a battery that actually MEETS *his**

*> minimum specifications:*

*> For example, the 6AS190:*

*> > GG spec: B13 Capacity of battery bank at *100* hr rate (B12 x B10) =*

*
*180**
*> Mfg spec for 6AS190: Capacity at *100* hr rate = *184**

*> Going back to the OP's requirements to run a 2500W pump for 30 minutes, we*

*> can see by simple mathematics that this battery, which MEETS George's*

*> "minimum" requirements, cannot work.*

*> Again, according to George's specifications:*

*> A4 Inverter Efficiency = 85%*

Actually that 85% was supplied by you

*> A7 System Voltage = 12*

*> So, for the 1/2 hr, our 2500W pump causes the inverter to draw current at a*

*> rate of: 2500/0.85/12 = 245A*

*> The 6AS190, which MEETS George's minimum requirements, when subjected to*

*> this current draw, has a capacity of well under 50AH. As a matter of fact,*

*> examining the capacity current curve published by the manufacturer suggests*

*> that the capacity, at this current draw, is no more than 30AH, and likely a*

*> good deal less.*

It will be noticed that Tweedledee has already claimed that the 6AS190

meets capacity. Unfortunately he did not take into account the fact

that the C rate is C.5 so his claim is incorrect. No surprise there.

*> In other words, a battery that actually MEETS *George's* minimun*

*> requirements will run the pump for 30/245*60 = 7 minutes at the very most.*

As I did not set any requirements your statement is a lie.

*> He needs to specify a battery that is almost six (6) times his minimum*

*> requirement of 180Ah at the 100hr rate to get a functioning system.*

180Ah is the minimum required at C.5.

*> Wow, what a deeziner!! Or, as Nick Pine would have said, "What a nitwit!"*

Tweedledee has yet to show his calculation for his wonderful

revelation. That's because like his bunk mate he does not know the

calculation. He googled "Peukert" and used a calculator he found

there.

He should have read the information at:

http://www.smartgauge.co.uk/peukert3.html

Which says;

The usual form of Peukert's equation is T=C/In

Where:

T = time in hours

C = the Peukert capacity of the battery (ie at the 1 amp discharge

rate)

I = the discharge current

n = Peukert's exponent.

This equation will only work on batteries that are specified at the

"Peukert Capacity" ie the 1 amp discharge rate. They very rarely are.

Batteries are usually specified at an "hour" rate, for instance

100Ahrs at 20 hours. Or 90Ahrs at 10 hours etc.

If your batteries are specified in such a way (and they nearly always

are) then the equation must be modified to take this into account.

The modifed equation is T=C(C/R)n-1/In or T=R(C/R)n/In

Where:

T = time in hours

C = the specified capacity of the battery (at the specified hour

rating)

I = the discharge current

n = Peukert's exponent

R = the hour rating (ie 20 hours, or 10 hours etc)

Alternatively, do this:

R(C/R)n = the "Peukert Capacity".

So in the case of a battery specified as being 100Ahrs@20 hours with a

Peukert's exponent of 1.25 we get:

20(100/20)1.25 = 149.5Ahrs. This is the "peukert capacity". ie the

capacity of the battery when discharged at 1 amp.

If you use this figure as the capacity of the battery then the usual

Peukert's equation of T=C/In can be used.

You see, Tweedledee and Tweedledum have no knowledge of their own.

They always rely on someone to be there to hold their hand.

Notice again that neither Tweedledee or Tweedledum have supplied any

maths to support their claims. This being the case there is really no

point to carry on with this thread until they can provide empirical

proof with real numbers. And we all know that that won't happen any

time soon.

The formula is correct and will correctly size a stand alone PV system

as long as the user supplies the correct specifications for the

equipment used.

The Spread Sheet is free as is any discussion you may wish to indulge

in concerning it's use.

Posted by *Ron Rosenfeld* on July 26, 2008, 9:01 pm

On Sat, 26 Jul 2008 07:53:00 -0700 (PDT), bealiba@gmail.com wrote:

*>> The 6AS190, which MEETS George's minimum requirements, when subjected to*

*>> this current draw, has a capacity of well under 50AH. As a matter of fact,*

*>> examining the capacity current curve published by the manufacturer suggests*

*>> that the capacity, at this current draw, is no more than 30AH, and likely a*

*>> good deal less.*

*>It will be noticed that Tweedledee has already claimed that the 6AS190*

*>meets capacity. Unfortunately he did not take into account the fact*

*>that the C rate is C.5 so his claim is incorrect. No surprise there.*

Stop lying, George. (if you can)

My claim, which you cannot dispute, is that the 6AS190 meets YOUR minimum

requirements as YOU posted them.

Your continued lies that you did not post a 100hr rate is easily refuted by

reviewing your posts.

The fact that you continue to deny this only lends credence to the idea

that you had no idea, at the time you posted it, that there might be a

difference between the 100 hr rate, and the capacity of a battery when

drawing high currents.

YOU are the one that posted a capacity at the 100 hr rate.

*> GG spec: B13 Capacity of battery bank at 100 hr rate (B12 x B10) = 180*

The battery you finally decided to come up with has almost 6 times the

minimum capacity YOU specified.

------------------------------------------------

Then you go on to copy a page from

http://www.smartgauge.co.uk/peukert3.html

which further demonstrates your lack of understanding of either battery

chemistry or the validity of what I had already posted.

But at least it shows that you might be trying to do some work to try to

learn about this issue.

Even though you show some ability to copy & paste, you fail to point out

that Peukert's exponent is not a constant over the entire range of the

battery discharge currents. Probably you don't know that since it wasn't

mentioned on the web page you just found on a Google search.

If you do some digging, you'll also find on that web site a method of

calculating Peukert's exponent!! They use a slightly different formula

than I. For extra credit, try to explain why there are small differences

between my calculations and the one's you get if you use their calculator.

But for now, you haven't even come up with the correct exponent to be used

for either your minimum battery, or the 6-fold greater battery that you

finally decided on.

For the battery YOU specified -- the ONE that *I* wrote had a 100 hr

capacity of 1047Ah we determine that for current draws of from 9.17 amps to

19.73 amps, Peukert's exponent = 1.196

So, using the published figures for the battery YOU suggested, we come up

with a 100 hr capacity of 1068Ah vs the 1047.537Ah I calculated using the

method which you didn't understand. My-oh-my -- that's almost a 2%

difference! (I sit duly chastised for such an egregious error. I was

using a polynomial curve-fitting algorithm rather than Peukert).

But there's a funny thing about using Peukert's exponent as you get down

into the very high current draws for these AS batteries -- it gets higher

and higher. So if you were to use, for example the 10 hr and 1 hr rates,

you would calculate a Peukert's exponent of 1.564. And this is more

appropriate given the high current draws to which these batteries will be

subjected.

However, this is not particularly important when using a battery that is

almost six (6) times your recommended minimum size, but:

Going back to the battery which meets YOUR minimum specifications of

*> GG spec: B13 Capacity of battery bank at *100* hr rate (B12 x B10) = *180**

We find the following:

For current draws from 1.63 amps to 3.31 amps

Peukert Exponent = 1.294

and its capacity at the 100 hr rate is 187Ah (exceeding GG's minimum

specifications of 180Ah at the 100 hr rate).

However, for current draws from 12.88 amps to 50 amps (the maximum currents

published by the manufacturer), the Peukert Exponent calculates to 1.533

and the battery capacity, when drawing 240A for the OP's pump, will only be

21.67Ah. (Using the mfg curves, I estimated it at less than 30A and a 7

minute runtime, but it's obviously even worse than that).

Oh, for George's benefit, even though the manufacturer did not publish

current draw, it is easily calculated from the published data by dividing

Capacity by Time.

If you really want to go into depth about the subject, look at the other

pages of that website -- don't just copy/paste the "in brief" page and

expect accolades.

And I've given you enough hints that, if you really understand things, you

should be able to explain the small differences between my results and

those you might get using that web site's calculators.

--ron

>B7 specifies a battery. I did not specify a battery.>B7 specifies a battery. I did not specify a battery.>B7 specifies a battery. I did not specify a battery.>B7 specifies a battery. I did not specify a battery.