New Door for Area Where Norcold Used to Live

[Pat Anderson]

OK, well, David made us a beautiful Decraguard door trimmed in teak for the area under the helm seat where the Norcold used to live! Looks just like factory manufacture! Got the Decraguard from Roger and Janet (former Dreamer). The C-Dory factory (a few miles down the road from us) sold us the offset hinges we needed, thanks guys! Tomorrow the door gets installed. I will put up a few pix!

The ARB is on its slide-out drawer under the galley, and so far so good - I used ordinary inexpensive side mounted drawer glides rather than the $$$ heavy duty under-mounted glides. No apparent springiness, time will tell, easy to change out if we have to. This is not a "project-a-palooze," hey, this is Pat here, not David or Ray, but so far it seem functional! Has been running off the solar panels all day as a freezer at 15 degrees with the battery SOC staying at 100%. Stay tuned for morning report!

[Ray]

Sounds GREAT!!
I am jealous of your panels!

[Pat Anderson]

SOC about 9:30 p.m. last night several hours after sun went down was 98.1%. SOC this morning, before sun has started shining, is 85%. It looks from the Victron that the current draw is about 5 amps, just the freezer and a little fan in the Airhead. Much higher than I expected. But SOC is what counts I guess, and we'll see how long it takes to get back up to 100%! Being able to run the ARB all night without running the battery down too far and recharging without running the engine or being plugged into shore power was our goal, and it looks like that is working.

[Jake]

Pat, what is the lowest SOC % you would be comfortable reaching?

Jake

[rogerbum]

Pat,
Just out of interest, what are you using the estimate the state of charge? If it is the Victron, won't your conservative amp hour setting result in a lower state of charge? If you are using voltage as your estimate, then ignore what I just said.

[thataway]

Great on the solar panel. I may have missed it--but what type and wattage of the panels. 5 amps is about what I figure for the freezer when running. We figure about 50% of the time running. Be sure that there are not some memories in GPS, Stereo, etc. You should be able to turn items on and off and watch the monitor to see how many amps each is drawling.

[Sunbeam]

I see what you are saying on the SOC, Roger. That seems like it might be true.

I think I have/had an issue where I didn't initially get things right on my Victron re: SOC. That is because I was underway when I "zeroed" the SOC. So in other words the battery was at full charge, BUT, I think the alternator on the outboard had probably really only got it up to 85% (at least from what I'm reading about how they do/don't work). So "my" 100% was really maybe only 85-90%.

I later put my shoreside trickle charger on it for a period of days until I believe it really was at 100% and then "re-zeroed" the SOC. So now I think when it reads 100% it really is (until some time down the line, when I need to re-set my total amp hour capacity to account for aging battery).

Maybe this was too much of a tangent, but OTOH I figured it's on the subject of getting baselines set up properly on the Victron or other battery monitor.

I'm looking at adding solar panels to my 22. Thinking that at least for starters I will set them up on a roof rack vs. mounting them right to the roof. They would be shaded if I carried a dinghy on the roof, but then I figure when I'm underway the engine will be charging and if at anchor for some time (when I would most want the solar) the dinghy would often be down. For now I'm just going to have an inflatable kayak anyway.

Sunbeam

[Pat Anderson]

OK, the next day report, and some questions answered. We have two Renogy 100 watt panels. They are of course not ideally situated, but they are in about the only place they can be on a CD25 if I want to put the dinghy on top as well! The Victron is a real eye-opener though, we are only getting a small fraction of rated output from the solar panels, on the order of 1/10th to 1/5 or so.

The panels run the ARB freezer during daylight hours and the SOC stays at 100%. SOC was based on a fully charged battery from the onboard Guest charger when I synced the Victron. I ran the ARB all day, and the SOC stayed at 100%. The sun went down, and I let the ARB keep going. First surprise, although the literature says it draws an intermittent 1.35 amps, the Victron showed current flowing after dark at closer to 5 amps, with only the ARB and an 80ma fan for the Airhead as the load.

I let it go all night, and in the moring the SOC was 85%. That did not seem so bad. The problem became apparent as the day went on however. The panels were again running the ARB but the recovery of the batteries SOC was excruciatingly slow. So I turned the ARB off and the SOC fairly quickly went back up to 100%.

I think the lesson here is that we will run the ARB during the day and turn it off at night. It is very well insulated and whatever is frozen inside it will still be frozen in the morning, since it is well insulated and we have not opened it!

We are still feeling our way along, and I definitely think we may have some unexplained current draw going on, since the current flowing well exceeds the published specs for the ARB. Maybe some electrical detective work to do. We shall see.

[Sunbeam]

One other thought: You mentioned not getting much output (or rather, input) from the panels. What size cabling did you use between the panels and the controller and the controller and the batteries (and what is your round-trip run length?) What percentage of voltage drop did you plan for? (You may already have told us this and I forgot.) I have noticed that many times companies (even solar companies!) will undersize the cabling leading from the panels to the controller and/or controller to batteries. Unless one has a lot of excess solar capacity, I'd want to shoot for 2% or less voltage drop (although 3% is commonly acceptable). I just wondered if this might be a "hidden" area where some loss is occurring.

[Pat Anderson]

We have standard cables with MC4 connectors, don't think anything is undersized! What I think is going on is that the panels are not ideally situated, and not facing the sun most of the time. Plus we have a PWM controller rather than an MPPT controller. But we are not unhappy! The panels will do what they will do! They still kick out enough power to run the ARB during daylight hours and maintain 100% battery charge. We will figure out the operational issues!

[jkidd]

Put your multimeter in the circuit and check the current draw with that to compare against the Victron. You can also aim your panels at the sun just for a test and get some readings to see if everything is all right. So at 85 percent your voltage should read between 12.5 and 12.62 volts. If it's doing that your good to go. If it's not then you need to adjust Cb by what ever percentage of error.

[journey on]

Pat,

I had a couple of solar panels on Our Journey, a sailboat, with much of the same results that you're getting. They would run the refer during the day, but not recharge the batteries.

Now, Pat, I know you don't like technical jargon, but here's what's going on. Unfortunately numbers are needed to describe that. Sorry.

First, note that the rated panel output is measured in the factory at a low temperature with a light flash. A good way to test the output of a panel after manufacturing, but in real life that output should be de-rated at least 25%. So you have 2 ea 75 watt panels. That's not too bad.

Next comes the real reason those panels aren't producing their full output. Any solar panel has its maximum output when the sun is directly overhead, the sunline is perpendicular to the panel. Laying them flat on the top of a boat doesn't point them at the sun. And the output falls off as the cosine of the angle.

First, you're at a latitude of ~48 deg, so they have to be tilted up at 48 deg. If you don't, you're only getting 67% of the expected output. Next, the sun goes from horizon to horizon, lets say from 20 deg E to 20 deg W. If the flat panel isn't rotated so it tracks the sun, run the numbers through that and you only get 2/3 of 67%. That's 44%, less than half.

So, Pat, if you've read this far, that 100 watt rated panel is averaging 75 watts x 44% = 34 watts. You have 2, so that's 88 watts, average.

Now, Pat, 88 watts x 10 hrs = 880 watt hrs, or .88 Kw-hr. And that's if the sun shines all day (no clouds, etc.)

5 amps at 12.5 volts for 24 hrs. is 1.5 Kw-hr. So what you're seeing is what's going on. Those panels are putting out about 1/2 of what you need.

Sorry about the math, Pat. But that's the only way to describe it.

Boris

[thataway]

In looking at the specs for the ABR freezer, it uses the standard Danfoss compresser. No way that is only 1.35 amps. They might be able to say it averages 1.35 amps in some conditions (low ambient temperature). We have a Dometic CF 50--and use the insulating jacket, have a 1/2" reflective foam board we put on top, and keep a damp towel over the unit when not in use. All of this keeps the demand for power down.

Also, what do you have inside the freezer now? Water, Food, or nothing. It will do much better when "full". If you want to add items to the freezer the best time is when there is a good current generation. Any empty freezer is not going to give you the same findings as a full freezer

You might want to do a "tracking" study, for your education…that is aim the panels directly to the sun, and measure current output, then tilt 10 degrees on each axis, and see how much drop off there is, for your specific panels. There are a number of studies on this, but to have your own, will be very useful. Generally you should be getting 72% of rated output during most of the day, but it will vary with tilt.

Optimal conditions, the 100 watt panel is going to be putting out about 5.5 amps…two (11 amps) should be plenty to charge the battery, and run the freezer. I think a lot will depend on orientation.

Do you have a digital volt meter (hand held)? You need to measure the amps directly from the solar panel to the battery, with the volt meter (use the 10 amp circuit, battery discharged about 10%). Then put the meter in series and see what the current use of the freezer is. Finally put the meter between the battery post (+) and the house load. I understand you have the Victron, but there may be something else going on, and that is why I would want to measure directly.
(Alligator clips which fit have the other end which fit over the probes for the volt meter are very handy in doing this test.)

Sometimes these things are not "plug and play"…and one has to sort out what is going on. I think that the 200 watts of panel should easily support your freezer being on. One of the problems with leaving it off during the night, is that it will "loose cold", and that will have to be made up during the daytime.

on edit:I was writing my post apparently while Boris was writing his. Your panels are rated at the 5.55 amps, considering 18 volts output (which it requires to charge the battery). Boris goes into more detail about the angles and that helps you even more..He is 100% right. You have to know actual output-and that has to be measured, as you use the voltmeter and change the angles. (One other advantage you have is a longer sunlight period during the summer in the PNW, but as you come down to Powell, you will be at about 37 degrees.)