Quote:
Originally Posted by Waterrat10
So in Amp hours if you are at say 80 amp hours at R10 then R20 is not going to save you 40 amp hours but but maybe 4 amp hours.
Depending on the temperature difference inside vs outside R10 (90%) would be a little low but best bang for buck where R20 (96%)can save a couple more amp hours but R40 (98%) might only save an additional 0.5 amp hours.

Absolutely incorrect and wrong application of the Data.
I have years worth of real life lab testing data to prove it. And a little time with
Google and you would see the problem with your "math".
Personally, I don't care if you are wrong...it doesn't bother me it's your warm
beer and energy usage to deal with as you like.
The only reason I have to call ******** is that this is exactly how Chat Room and
Dock rumors get started and then some poor Cruiser thinks all he needs is a R10 box because some "expert" on the
internet said so and posted a pretty graph. The only problem is the "expert" seemingly is having a problem taking the graph data and applying that to the real life situation of a
refrigeration box. Sure there is a diminishing efficiency return on a Per Inch basis of insulation, but a standard
refrigeration rule of thumb is that when you double your box Rvalue you cut the power usage in half and that has been pretty well known and established in the refrigeration industry long before you or I came into the scene. The misleading graph you presented even proves the point if you know how to apply the data presented. So lets look at the data from the graph so others won't make the same mistake.
At R10 the graph shows 10MMBTU rate of heat transfer
At R20 the graph shows 5MMBTU rate of heat transfer
Then at R40 the graph shows 2.5MMBTU rate of heat transfer
Now, since heat transfer rate is directly proportional to system power usage and thereby Amp Hour
consumption, it's pretty clear that it will take about twice the daily power to deal with a 10MMBTU heat transfer rate Box with R10 than it would with a Box with a 5MMBTU heat transfer rate with R20. Same in going from R20 to R40.
If you half the heat transfer rate, you half the energy needed to pull said heat out of the box and keep your
beer cold and ice cream hard.