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melvin2345 05-03-2021 07:01 AM

First boondock, need more solar, battery seems good
 
We took our first boondocking trip since the panels went up. Started small, leaving ample wire slack to add more if needed.

Our setup:
2 x FullRiver AGM 250ah 6v
2 x 200w Rich Solar Mono panels
40a Rich Solar MPPT controller
AiLi Battery monitor w/ 350a shunt
2000w Renogy Pure Sine Inverter

I wanted to test using 'normal' conditions, knowing we could always use the generator if needed.

Day 1
Panels stopped carrying the load around 6:45pm, at which point we were at 250ah on the monitor.
Furnace was set to about 66.
We watched about an hour of TV before bed, left the inverter on to charge phones overnight.
Just before bed at 10, monitor read 226ah
It got down to like 25 degrees, so the furnace was on quite a bit.

Day 2
Woke at 6:30, checked monitor, read 144ah. Not bad at all considering the furnace was cycling a lot.
The panels didn't start producing a surplus until around 11:30-12, at which point the monitor read 102ah.
They did well throughout the day, even during the shady/rainy bits.
They stopped charging/carrying the load about the same time, 6:45ish, monitor read 215ah.
Same as the previous night, watch TV for an hour, went to bed at around 10, monitor read 188ah.
Temps only dropped to the 40s, so furnace wasn't on as much.

Day 3
Woke at 6:45, monitor read 112ah
We pulled out to go home around 11, so the panels didn't get a chance to do much of anything.
Last monitor reading was 84ah (the FullRiver manual says 80% discharge is acceptable use, so I didn't feel bad about letting it get this low just once)


Summary
I am of the opinion that we have enough battery to do what we normally would do, but I think I should get 2 more of the 200w panels. This was only a weekend trip, so it was a good test, but there is no way we could have done more than that without being able to charge the batteries to full each day.

Does this assessment seem correct? Should I concern myself with the battery bank as well?

astrocamper 05-03-2021 08:24 AM

You would save quite a bit of energy turning off the inverter overnight. It is pretty easy to charge phones using a 12 volt adapter. Keep the inverter on only when needing 120 volt loads. The standby draw of the inverter can be significant. Go look at your battery monitor and compare the draw with the inverter on with no load verse turning it off.

We use a small inverter for our Dish Wally, 40 inch TV and Apple TV device so we can turn the big inverter off when not needing it.

BCam 05-03-2021 08:38 AM

You didn't mention what kind of refrigerator you were running. As you know, the heater can be a power hog. You might want to consider a supplemental LPG heater like an Olympian Wave Heater. Did you run other appliances off the inverter other than the TV?

We camped for several years with 200W on a 25' TT before we bought our MH and never really had a problem. I have 320W of solar that's waiting to be installed on our MH.
However, we came to RVing from sailboating and were very conservative with power usage. If you think "camping" instead of "RVing" in terms of power usage it will make a lot of difference.

Nwcid 05-03-2021 08:56 AM

You are on the right track. Mostly it depends on your budget and your expectations.

If you plan on doing a lot of boondocking I would add both more batteries and solar.

For the best battery longevity it is recommended not to discharge below 50% which means you have 125AH of useable capacity. As you saw, this can really get used up overnight.

I am sure you already know, or just learned this but panels only make full power a few hours per day. For every 100 watts of solar you get roughly 5 amps of 12v charging at peak performance. So in your case you get just over 10 amps at peak which is usually only about 6 hours.

From leaving your house to waking up you used 150AH of power. That means you would need a least 15 hours of charging at 10 amps to fully recharge.

Something that many of us do to supplement the charging, especially on bad solar days (rain, snow, smoke, late/early season) is to run the generator for an hour or so in the morning and evening. The built in charger has a much higher output to charge with.

melvin2345 05-03-2021 09:20 AM

Quote:

Originally Posted by BCam (Post 5736352)
You didn't mention what kind of refrigerator you were running.

Norcold 4 door. On LP the draw seemed like it wasn't very much at all, though I never took the time to isolate that to get an exact amount.

twinboat 05-03-2021 09:36 AM

I don't know the exact inverter your using but one I looked at has a < 2 amp idle draw.

Lets say its 1.5 amps. At 24 hours a day if you leave it on, that's 36 AH wasted.

For those following, chect the idle draw before buying your inverter. Xantrex ProWatt 2000 draws <.5 amps.

SJ-Chris 05-03-2021 01:07 PM

Quote:

Originally Posted by melvin2345 (Post 5736237)
We took our first boondocking trip since the panels went up. Started small, leaving ample wire slack to add more if needed.

Our setup:
2 x FullRiver AGM 250ah 6v
2 x 200w Rich Solar Mono panels
40a Rich Solar MPPT controller
AiLi Battery monitor w/ 350a shunt
2000w Renogy Pure Sine Inverter

I wanted to test using 'normal' conditions, knowing we could always use the generator if needed.

Day 1
Panels stopped carrying the load around 6:45pm, at which point we were at 250ah on the monitor.
Furnace was set to about 66.
We watched about an hour of TV before bed, left the inverter on to charge phones overnight.
Just before bed at 10, monitor read 226ah
It got down to like 25 degrees, so the furnace was on quite a bit.

Day 2
Woke at 6:30, checked monitor, read 144ah. Not bad at all considering the furnace was cycling a lot.
The panels didn't start producing a surplus until around 11:30-12, at which point the monitor read 102ah.
They did well throughout the day, even during the shady/rainy bits.
They stopped charging/carrying the load about the same time, 6:45ish, monitor read 215ah.
Same as the previous night, watch TV for an hour, went to bed at around 10, monitor read 188ah.
Temps only dropped to the 40s, so furnace wasn't on as much.

Day 3
Woke at 6:45, monitor read 112ah
We pulled out to go home around 11, so the panels didn't get a chance to do much of anything.
Last monitor reading was 84ah (the FullRiver manual says 80% discharge is acceptable use, so I didn't feel bad about letting it get this low just once)


Summary
I am of the opinion that we have enough battery to do what we normally would do, but I think I should get 2 more of the 200w panels. This was only a weekend trip, so it was a good test, but there is no way we could have done more than that without being able to charge the batteries to full each day.

Does this assessment seem correct? Should I concern myself with the battery bank as well?


Great summary!


You have 250AH of battery and 400w of solar. You are FINE and don't NEED more solar or batteries (based on your current usage).


My 2000w inverter draws about 2 amps sitting idle, so I only have it on when it needs to be on. If yours is similar, then 12hrs overnight used up 24AH from your battery (totally wasted). You can install VERY EASILY some usb charging ports for your phones by tapping near one of your lights. I installed them in 3 locations throughout my RV. Then you no longer need the inverter on to charge your phones. These ones are SIMPLE to install (just need the right size drill bit) and are short enough to fit in the space of your underside cabinet where your lights are:
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

They take less than 10 minutes to install and then you are golden.



You mentioned the panels didn't start delivering a surplus until 11:30am. That MUST mean that you were in clouds or rain or shade. If that's the case, adding more solar panels would not have helped as much as you would like. If you were camping and the sun came up at 7am your panels will start producing a surplus at 7am and your batteries would be back up to 90-95% by 1pm. Note: The last 5% of charging batteries with solar takes a LONG time so don't ever make 100% your benchmark.


I think the "Don't let your lead acid batteries go below 50%" mantra is WAY overstated. If you look at specs from the manufacturer you will see that TOTAL battery lifetime capacity use isn't affected very much if you discharge to 70-80%. Yes, you will get less lifetime cycles, BUT you used MORE capacity/charge during each cycle. I'm guessing that 99% of all RV/Trailer owners will never boondock 300-500 days over a 5-6 year period and "use up" their battery. Most batteries die from being fully discharged to 0% multiple times and/or left at 0% for any length of time.


If your 2000w inverter and 2 6v batteries delivers all the current you need to run any appliance you want (ie. microwave being among the largest draw), then you don't need more batteries.


Of course, adding 1 more 200w panel is probably EASY if you really felt the need. But I would just enjoy what you have for 4-5 more boondocking trips and see if you actually NEED more solar/batteries. You always have the option/backup of running the generator in an emergency (or run your engine).



You probably don't need more solar or batteries.



Side note: Solar and batteries are ADDICTIVE! LOL. I'll be adding 100AH more (to get me to 300AH) in my RV soon. I've got 500w of solar (overkill, but it was dirt cheap). My motivation for more batteries is to be able to handle the large draw of the microwave. I'm hoping 3 lead acid batteries (and large wires) is enough to run the microwave.


Happy Camping!
Chris

JHinman 05-03-2021 09:59 PM

That is a great summary!

I am going through the same kind of evaluation with my new trailer, as this is the first time I have had any solar. The last 30+ years of boondocking has been LA batteries and a small generator.

Last week I was in a fancy park, and had clear and unobstructed sun for maybe four hours, plus or minus. I was getting a net gain from my 170-watt Zamp panels of 7 or 8 amps. I was pretty happy about that, and thinking maybe adding some additional solar would be a good idea. However, the tiny bit of shade from some leafless trees cut that back to about 1 amp or less as soon as the shade hit my panels.

In a couple of weeks I will be back at one of my favorite old Forest Service campgrounds, and will see what I get there. I suspect the shade will cut production pretty heavily, but until I try I won’t know.

vsheetz 05-03-2021 10:48 PM

I'm in the camp of putting as many watts on the roof as can practically be accommodated. There are many variables to PV production. Flat mounting reduces 10-15% from specifications. Low january sun increases that to nearly 50%. Additional limiting may be self shading from other items in the roof. So more is better.

Imho.

melvin2345 05-04-2021 06:52 AM

Quote:

Originally Posted by SJ-Chris (Post 5736734)
These ones are SIMPLE to install (just need the right size drill bit) and are short enough to fit in the space of your underside cabinet where your lights are:
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

They take less than 10 minutes to install and then you are golden.

These are perfect. Just ordered 3. I can pop 2 in the bedroom (1 on each side of the bed by the night lamps) so we can have our phones near us when charging and turn off the inverter at night. I'll stick the other one near the kitchen so the kids can charge their tablets. Thank you for the tip.

BCam 05-04-2021 07:03 AM

I realize this is an experiment to see what's possible but, in real life, you can save a lot of battery power by running the microwave off the generator. Running the genny for a few minutes to power the microwave isn't too intrusive and well worth the savings in amp-hours.

melvin2345 05-04-2021 07:05 AM

Quote:

Originally Posted by vsheetz (Post 5737352)
I'm in the camp of putting as many watts on the roof as can practically be accommodated. There are many variables to PV production. Flat mounting reduces 10-15% from specifications. Low january sun increases that to nearly 50%. Additional limiting may be self shading from other items in the roof. So more is better.

Imho.

That's the way I'm leaning. 2 more panels are going up either way to get me to 800w on the roof.

The real question is: Save myself $650 and teach myself and my family better power discipline, or just accept that the we are who we are and get two more batteries, lol.

melvin2345 05-04-2021 07:16 AM

Quote:

Originally Posted by BCam (Post 5737540)
I realize this is an experiment to see what's possible but, in real life, you can save a lot of battery power by running the microwave off the generator. Running the genny for a few minutes to power the microwave isn't too intrusive and well worth the savings in amp-hours.

Not a bad idea. I'm not sure we've used the microwave even once since we got this motorhome. We cook everything on the stove or over a fire.

In our case, however, it's the Keurig. This last trip was the last one with the current one we have. Using it drew 135amps for about 2 minutes while it warmed up the water. Maybe 1/4 of that for each subsequent cup. They make models that use half that now, so that is one change we will be making.

The other thing we are going to get is a percolator I can use over the fire. I'm up with the sun, and first thing I do is go outside to start a morning fire. I can use that to get some coffee going while the sleepy heads do their thing.

SteveJ. 05-04-2021 07:25 AM

I installed these for the excellent lighting and the built in USB port on the base.

I like 'em.


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