I use my RV year round. One of the advantages of living where I do is it is often windy--windy enough to clear the snow off solar panels! That said this is my first year with my new to me RV and the new solar system.
atreis wrote: Unless you're trying to see how long your batteries will last when camping in the winter (not very long if you have to run the heat, especially if they can't recharge at all), this test makes little sense to me.
I live WAY south of there and left my batteries hooked to my 115W panel throughout the winter last winter with only parasitic loads, and the batteries still reached less than 50% charge at one point because of snow on the panel. This winter I made sure they were fully charged and disconnected them.
If you need power for brief periods in the camper (for instance, to run lights so that you can check for mice - NOT for running the heat or any other significant load) you can (briefly) hook one of those car jumpstarter doohickies that has a battery in it into the 12V outlet in the camper.
When some one asks a simple question or post their results. Why is there always some one that wants to post a sarcastic reply ?????
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It was my first chance to see how my solar panels fared with snow this morning. Time was 10 a.m.
There was less than one centimeter of snow and output is zero.
Batteries were at 12.4 volts as I forgot to turn off the inverter over night--it was 12.5 last night.
I'm doing a load test by running two heaters with a total wattage of 2127 watts for 30 minutes. Voltage dropped immediately to 12.0 measured at the charge controller. I have deliberately plugged them into the same outlet--I want to know what those 15 amp breakers will do. (i.e. it should have tripped immediately and it did not). I did not think to plug in my kill-o-watt meter--oh well!
I'm combining this with a heat rise test--RV was at 0.9 C. The outside temperature was -0.9 C
Results:
The breaker failed to trip under a load of 2127 watts. I feared that would be the case.
Battery voltage after 30 minutes under load displayed as 12.0. When the load was removed the display immediately bounced up to 12.2 volts
Battery voltage at charge controller after 5 minutes of "rest" was 12.3 volts
Temperature in the RV was 6.5 C. Outdoor temperature was -0.4 C.
Please feel free to interpret the results--and to post your own results to this thread.
Good post there is some great information here Thanks for posting it.
It was my first chance to see how my solar panels fared with snow this morning. Time was 10 a.m.
There was less than one centimeter of snow and output is zero.
Batteries were at 12.4 volts as I forgot to turn off the inverter over night--it was 12.5 last night.
I'm doing a load test by running two heaters with a total wattage of 2127 watts for 30 minutes. Voltage dropped immediately to 12.0 measured at the charge controller. I have deliberately plugged them into the same outlet--I want to know what those 15 amp breakers will do. (i.e. it should have tripped immediately and it did not). I did not think to plug in my kill-o-watt meter--oh well!
I'm combining this with a heat rise test--RV was at 0.9 C. The outside temperature was -0.9 C
Results:
The breaker failed to trip under a load of 2127 watts. I feared that would be the case.
Battery voltage after 30 minutes under load displayed as 12.0. When the load was removed the display immediately bounced up to 12.2 volts
Battery voltage at charge controller after 5 minutes of "rest" was 12.3 volts
Temperature in the RV was 6.5 C. Outdoor temperature was -0.4 C.
Please feel free to interpret the results--and to post your own results to this thread.
Hi Don,
2127w is equal too 7227btu or about 4 times smaller than your LP furnace.
The Delta(the difference between the outside and indoor temperature) is about 11ºf(-11ºc) or about what I would expect on a typical RV at your temperatures while using 7000btu of heat.
A typical 4" insulated wall on a stick house should hold approx 10ºf delta without any additional heat being added.
A typical 6" insulated wall on a stick house should hold approx 15ºf delta without any additional heat being supplied.
I would expect about a 5°f delta on a typical RV and maybe lower on older units. I've never measured one nor looked up the spec's so I'm taking a educated guess here.
If your heat load requires 30000btu/hr to maintain comfort(human or building), it doesn't matter what source supplies that heat as all heat sources would have to be able too out put 30000btu/hr.
I don't know where your heading with your project, so I was just supplying some general engineering info too think about.
T_Bone
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Please do not trust everything you read on the internet. Use only valid engineering information from well established Companys.
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The Delta(the difference between the outside and indoor temperature) is about 11ºf(-11ºc) or about what I would expect on a typical RV at your temperatures while using 7000btu of heat.
A typical 4" insulated wall on a stick house should hold approx 10ºf delta without any additional heat being added.
A typical 6" insulated wall on a stick house should hold approx 15ºf delta without any additional heat being supplied.
I would expect about a 5°f delta on a typical RV and maybe lower on older units. I've never measured one nor looked up the spec's so I'm taking a educated guess here.
Without additional heat added, the delta will eventually be zero. The time will be determined by the quality and thickness of the insulation.
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The Delta(the difference between the outside and indoor temperature) is about 11ºf(-11ºc) or about what I would expect on a typical RV at your temperatures while using 7000btu of heat.
A typical 4" insulated wall on a stick house should hold approx 10ºf delta without any additional heat being added.
A typical 6" insulated wall on a stick house should hold approx 15ºf delta without any additional heat being supplied.
I would expect about a 5°f delta on a typical RV and maybe lower on older units. I've never measured one nor looked up the spec's so I'm taking a educated guess here.
Without additional heat added, the delta will eventually be zero. The time will be determined by the quality and thickness of the insulation.
Hi Bill,
That would be true only if the structure was not sun exposed as the sun is now our heat source. If sun exposed and typical air tight, the structure should average the delta's stated.
If the structure was covered with snow or ice then our outside ambient would now be calculated at 32ºf as ice and snow is a great insulator.
A good example of this air chamber would be to pour boiling water inside of a foam egg carton, then close the lid. A typical foam cell holds approx 90% air content.
Using a IR thermometer, if we measured the water before closing the lid we would see about 190ºf water in the cell container and approx 77ºf on the outside of the carton cell wall. Now if we continue to take measurements on the hour, we would see about 155ºf inside the cell container and 77ºf outside. The second hour we would see 122º/77º and the third hour 77º/77º. The above experimint was performed last winter.
That's right, after 3hrs we have lost all insulating quality of the foam cell as convection took over and equalized the temperatures BECAUSE our test cell was exposed too ambient convection air currents on both sides of our insulating chamber.
And that's why you never put all your eggs in one basket? I always wondered why LOL.
T_Bone wrote:
A good example of this air chamber would be to pour boiling water inside of a foam egg carton, then close the lid. A typical foam cell holds approx 90% air content.
Using a IR thermometer, if we measured the water before closing the lid we would see about 190ºf water in the cell container and approx 77ºf on the outside of the carton cell wall. Now if we continue to take measurements on the hour, we would see about 155ºf inside the cell container and 77ºf outside. The second hour we would see 122º/77º and the third hour 77º/77º. The above experimint was performed last winter.
That's right, after 3hrs we have lost all insulating quality of the foam cell as convection took over and equalized the temperatures BECAUSE our test cell was exposed too ambient convection air currents on both sides of our insulating chamber.
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