The "nest" and its loads

[scrubjaysnest]

This will give you an idea of what power we need to make up with our solar.
These are worst case figures; some like the reefer fan, 12 hours or the inverter are rare occurrences. The water pump is 0 because from Dec 1 until the first week of March this year it was used only once. Notice this is enough usage to draw down the batteries to just below 50% soc for 1 day. Our more typical usage takes 3 to 5 days to get to 50% soc. This why an audit of what you use should be done first before going out and getting your solar system.
200 watts of solar * 3 hours = 600 WH so 5 hours of full sun will just make it.

Basic formulas:
All watts are E*I=W; in all cases E = 12 Vdc
WattH or WH are watts * number of hours device is used
All currents measured with DC clamp on meter.





Ok now it is more or less easy to follow.

Added updated table.

[LoveToCamp]

Scrubjay, I am not criticizing a bit, so please don't take it that way. While some of you on the forum have electronics down pat, there are some of us (at least me, anyway), that didn't pay enough attention in science to be fluent in electronic values.

So, a helpful column to add to your assessment is how many hours a day you factored for each item. This way, I could do some math with your numbers, and possibly figure out how to do a similar calculation for my use. Having the hours-used would allow me to verify that my way of thinking was correct (or incorrect).

Where do you get the values for each of your items, especially thinks like LED lights, refer fan, and things without obvious values? Dig for a label? I tried putting a multimeter inline with some items, and it didn't display a result that made sense to me, when I tried to determine the load to something last year. I have not figured out that process, yet.

Thanks for posting your results. Gives me something to try to mimic, to see how much extra capacity I have with my 100w panel. Batteries are topped-off every day when I am camping.

[scrubjaysnest]

Got to thinking about that after I posted I'll edit the original post. All currents were measured with a DC clamp on meter. Watts = Amps measured * 12 volts
for starters.

[Padgett]

That is how you create an energy budget though using a spreadsheet helps (If you don't have Excel, Open Office (free) has a good one).

Just ordered one of these because it has both AC & DC clamp on amp measuring and can measure capacitance to 4mf. Looks like an inexpensive all in one.

More when it arrives.
ps: the one with blue clamps is 50c cheaper but sounds like the same gutz.

[scrubjaysnest]

I ordered the one from Sears on line and picked up at the store to save on shipping. Some Radio Shacks also carry one. They get expensive if you buy from an electric supply house. Another choice is to put in a Trimetric or Clipper battery monitor. For the last two you install a shut in the negative battery load lead. The Trimetric gives you amps used, amps charged ,soc, watts and watt hours used or replaced and other stuff. From reading on the solar-electric forums you need to use care when setting up the Trimetric.

Have not really heard any thing about the Clipper.

[scrubjaysnest]

Kind of have the table more usable.

[tentcamper]

scrubjaysnest, Very nice chart. Good idea to have an understanding where you use your battery power.

What is the fridge fan? Is it the fan in the back for traveling or is it a fan inside the fridge?

We almost always have the water pump on because most CS we stay at don't have water hook-ups. But I don't think it runs for more than 5 minutes total during a day. I think it pulls from 4 to 7 amps when running depending on the pressure while it is running. But when it's not running, it's not pulling any current.

Have you figured our the load from the propane detector, radio antenna, and propane water heater??

[Bill]

Scrub Jays Nest -

That table is a really nice piece of work. Lots of information, and enough definition that we can all see where the numbers come from, and how to make changes if we would like different starting numbers.

I'm especially impressed that you found a way to format the table. VBulletin software is not very good at all for that purpose.

Bill

[scrubjaysnest]

Originally Posted by tentcamper

scrubjaysnest, Very nice chart. Good idea to have an understanding where you use your battery power.

For the amount of dry camping we do you need a good handle on power use.
Did some testing with the inverter and laptops and it took two days to get the batteries to 70% soc. That's with a 12 hour rest period. Solar with the cloud cover yesterday was in bulk between 3 to 12 amps. When I turned it back on at 8 AM this morning the CC was in absorb at 10 AM with 11.4 amps; for my settings that's 14.9 volts at the batteries or 170 watts from the 3 panels total. The roof mounted one had a bit of shade.

What is the fridge fan? Is it the fan in the back for traveling or is it a fan inside the fridge?

The fan to pull hot air from the top of the reefer. It's really a don't care for us as the first nights stop is a 4 hour drive so the TV puts that little bit back.

Some on the forum user do use it when camping in hot weather is why I put it in.

We almost always have the water pump on because most CS we stay at don't have water hook-ups. But I don't think it runs for more than 5 minutes total during a day. I think it pulls from 4 to 7 amps when running depending on the pressure while it is running. But when it's not running, it's not pulling any current.

This is why the math for the toilet WH; you have to convert seconds or minutes of run time to hours. For us we don't use the water p-p a couple of 2 1/2 gal water containers by the sink.

Have you figured our the load from the propane detector, radio antenna, and propane water heater??

The detector I haven't measured. The antenna is off as it's powered only when the radio might be on. We don't use the radio and it's un plugged as the amplifiers were always on.
Our normal usage is ~15% per day as a FWIW.


See post 14 for redo pictures

[scrubjaysnest]

I have up dated the table in the first post, did forget to add in times.
For the most part divide wattH/day by watts and it will give you an hour figure.
The toilet is based on 10 second flushes times an average number of flushes. That number will be lower then most as we don't put any solids in the toilet.

The furnace for us is usually two 15 minute cycles with the thermostat set at 60 degrees.

The inverter is a really hard one, worst case is two laptops charging for 3 hours at about 12 amps but it is rare for both to be charged even on the same day.

I added a portable O2 cool fan which runs from 10 pm to 5 am every night temps only get to about 70 degrees.