Posted by *Anti-Spam* on August 23, 2007, 6:15 pm

Nearly new to this topic, just need a couple of points of view on my

calculations for a small system design. Thanking you in anticipation.

Posted by *Anti-Spam* on August 23, 2007, 6:39 pm

Sorry could not post the file, try this instead please. Took me a

while, but I got there in the end.

http://www.satseekers.net/Sysize.htm

Posted by *bealiba* on August 26, 2007, 12:15 am

*> Sorry could not post the file, try this instead please. Took me a*

*> while, but I got there in the end.*

*> http://www.satseekers.net/Sysize.htm *

By way of further explanation,

The first thing you need is the energy audit which you have.

So if this load is to run from an inverter you need to calculate the

inverters loss at this point;

Load 720Whs X .9 = 800Whs / 12V = 66.67 Ahs

This is the actual load of your system including the inverter

inefficiencies.

Now you can calculate the battery requirement. You need to know the

days of autonomy (1) and the maximum allowable depth of discharge (%

recommended by manufacturer, say 70%) 66.67Ahs X 1day autonomy /

70%MaxDOD = 95.24 Ahs capacity.

This is then adjusted for 24 hour average daily temperature (say

10C); 95.24 / .96 = 99.21Ahs.

Now you can calculate the panel requirement. 66.67Ahs / battery

efficiency .9 = 74.07Ahs of panel output.

If you would like to have the complete spreadsheet drop me an email

and I can send it to you. The formula is progressive and should be

calculated in the correct order for best results.

Posted by *wmbjkREMOVE* on August 26, 2007, 3:00 pm

On Sun, 26 Aug 2007 00:15:34 -0000, bealiba@gmail.com wrote:

*>> Sorry could not post the file, try this instead please. Took me a*

*>> while, but I got there in the end.*

*>>*

*>> http://www.satseekers.net/Sysize.htm *

*>By way of further explanation,*

*>The first thing you need is the energy audit which you have.*

*>So if this load is to run from an inverter you need to calculate the*

*>inverters loss at this point;*

*>Load 720Whs X .9 = 800Whs / 12V = 66.67 Ahs*

*>This is the actual load of your system including the inverter*

*>inefficiencies.*

*>Now you can calculate the battery requirement. You need to know the*

*>days of autonomy (1) and the maximum allowable depth of discharge (%*

*>recommended by manufacturer, say 70%) 66.67Ahs X 1day autonomy /*

*>70%MaxDOD = 95.24 Ahs capacity.*

Previously you wrote that he needed 102Ah. You should make up your

mind which wrong number to use. You might also finally learn about

Peukert's equation and the effect it would have on discharging a

battery at ~ C/5 rate. http://www.amplepower.com/pwrnews/beer/ A

reasonable exponent of 1.1 would make your numbers another 30%

wronger.

*>This is then adjusted for 24 hour average daily temperature (say*

*>10C); 95.24 / .96 = 99.21Ahs.*

*>Now you can calculate the panel requirement. 66.67Ahs / battery*

*>efficiency .9 = 74.07Ahs of panel output.*

Why are the charger specs from B30 and B31 of his spreadsheet still

MIA from your calculations? Does it have anything to do with

"unexpected babies"?

*>If you would like to have the complete spreadsheet drop me an email*

*>and I can send it to you. The formula is progressive and should be*

*>calculated in the correct order for best results.*

Why would he start correspondence with a quack when spreadsheets are

readily downloadable from reputable sources?

http://www.lowexpecations.com/

http://www.citlink.net/~wmbjk/tbfduwisdumb.htm (just updated with

Ghio's spreadsheet)

Wayne

Posted by *bealiba* on August 26, 2007, 10:19 pm

On Aug 27, 1:00 am, wmbjkREM...@citlink.net wrote:

*> On Sun, 26 Aug 2007 00:15:34 -0000, beal...@gmail.com wrote:*

*> >> Sorry could not post the file, try this instead please. Took me a*

*> >> while, but I got there in the end.*

*> >> http://www.satseekers.net/Sysize.htm *

*> >By way of further explanation,*

*> >The first thing you need is the energy audit which you have.*

*> >So if this load is to run from an inverter you need to calculate the*

*> >inverters loss at this point;*

*> >Load 720Whs X .9 = 800Whs / 12V = 66.67 Ahs*

*> >This is the actual load of your system including the inverter*

*> >inefficiencies.*

*> >Now you can calculate the battery requirement. You need to know the*

*> >days of autonomy (1) and the maximum allowable depth of discharge (%*

*> >recommended by manufacturer, say 70%) 66.67Ahs X 1day autonomy /*

*> >70%MaxDOD = 95.24 Ahs capacity.*

*> Previously you wrote that he needed 102Ah. You should make up your*

*> mind which wrong number to use. You might also finally learn about*

*> Peukert's equation and the effect it would have on discharging a*

*> battery at ~ C/5 rate.http://www.amplepower.com/pwrnews/beer/A *

*> reasonable exponent of 1.1 would make your numbers another 30%*

*> wronger.*

*> >This is then adjusted for 24 hour average daily temperature (say*

*> >10C); 95.24 / .96 = 99.21Ahs.*

*> >Now you can calculate the panel requirement. 66.67Ahs / battery*

*> >efficiency .9 = 74.07Ahs of panel output.*

*> Why are the charger specs from B30 and B31 of his spreadsheet still*

*> MIA from your calculations? Does it have anything to do with*

*> "unexpected babies"?*

*> >If you would like to have the complete spreadsheet drop me an email*

*> >and I can send it to you. The formula is progressive and should be*

*> >calculated in the correct order for best results.*

*> Why would he start correspondence with a quack when spreadsheets are*

*> readily downloadable from reputable sources?*

*>*

*
http://www.lowexpecations.com/http://www.citlink.net/~wmbjk/tbfduwisdumb.htm (just*

updated with
*> Ghio's spreadsheet)*

*> Wayne*

Gee wayne, I forgot that you can reduce your load by using a charger.

How is that done wayne? Do you plug your charger into the inverter to

charge the batteries as you run your loads?

Is this the secret of the magical load reduction that gives you your

two days autonomy?

No numbers, no design, no hope.

> Sorry could not post the file, try this instead please. Took me a> while, but I got there in the end.> http://www.satseekers.net/Sysize.htm