Battery and solar

Guessing....
Either you are not getting the charge you might expect from the panels into the batteries, or the batteries are stuffed.
We need some real life data.
Is this a new problem or a new install or an old problem?
Cheers,
Peter
OKA196 motorhome

We need to know the type of battery chemistry -Lead Acid/Gel/AGM/ Lithium

Peter When I first brought it I went 3 days without any problems I’ve been been on power for the last 12 months

That suggests that it is a developed fault, not a bad design, but I would have expected it should have run forever, not just 3 days, if conditions were good, so maybe not an optimum installation either.

Does your solar controller tell you any useful information, like actual charge rate and daily input and output to and from the battery? Did you tell us the make/model of the solar controller?
Cheers,
Peter
OKA196 motorhome

"probably less than 50% of their rated capacity. "

Where did you get this data from?

Cheers,
Mark

.
Realised output of 50% of manufacturer's nominated rating sounds about right to me also.
The manufacturer's rating is an instantaneous value, attained in laboratory conditions with a nominated irradiance.
Real-life conditions are: a less-than-perfect sky, panel not oriented to sun, an occasional cloud or two, a bit of dust on the panel face etc.
Sure, you may see higher than 50% when you gaze lovingly at your display, but averaged over the day likely to be not quite so good.
Macca's assessment probably comes from observation rather than accurate measurement. So Silkwood, instead of challenging Macca, do you have verified data which refutes his opinion?

Here is some data (from memory).
My 5.2kW of home solar is 10 years old. They are mounted facing north at 5 degrees from flat. Adelaide gets 5hrs of sunshine per day (no idea where I got that from).
5 x 5.2kW = 26kWh/day.
The panels are actually in significant shade until about 10am - 10.30am during which time their output is very poor.
Actual energy collected varies from 6kWh to 40kWh. A "good day" is 30kWh.
Average over the last 12 months = 19kWh (from 10 year old panels)

Cheers,
Peter
OKA196 motorhome

.
Peter,
Sounds about right for domestic roof panels facing north at an angle. But the data relates to harvest, not potential and has little relativity to the expressions of vehicle mounted systems discussed above. But it may be useful to Silkwood.

Hi Mark (Silkwood),

The number I quoted is from my observations of my own system on the roof of my caravan. Flat roof mounted panels, total of 500 watts, I average around 200 watts and around 10 amps. These numbers were taken using the shunt and monitor over a 4 week period in Southern NSW in April a few years ago with the van sitting in full sun in a North/South orientation. Yes, it is not exactly a scientific test, but a real world experience. I have also read of other peoples observations from real world experiences with similar results to mine.

I also have a 200 watt folding solar blanket which I use for the Auxiliary battery in the back of my wagon. With the blanket laid across the windscreen of the vehicle facing north, using an inline monitor, the maximum I measured was 130 watts at 19 volts and 6.8 amps. This was at approx. midday, in July/August, located on the Dampier Peninsular in W.A. Again, not in absolute ideal conditions, but with the blanket on an angle, not flat.

If anyone believes that they are going to get anything like what the manufacturer states out of a solar panel, then they are sadly mistaken. The numbers stated by the manufacturer were gained in a laboratory in absolute ideal conditions.

Macca.

Those "laboratory conditions" that are the basis of solar panel performance measurement are 1,000W/m2 and 25C. They are not so arduous. Increased temperatures more often cause a loss of performance of up to 17% in extreme temperature conditions (less for some cells), but the 1,000W/m2 is commonly reached and very often exceeded.
The whole of SA, much of Queensland, the NT, NSW and Victoria currently exceed that rate (by up to 10% and more), right now.
https://www.windy.com/-Menu/menu?solarpower,-33.549,140.543,6,m:cGVaj0g
And reflection from clouds, beaches and sand dunes can cause readings to be MUCH higher.
Some of the best solar panel performance we have ever seen was in Tasmania when the sun shone and the temperature was low.
Cheers,
Peter
OKA196 motorhome

.
Peter, with respect, you are equating Standard Test Conditions to actual field conditions without making allowance for the declination of the sun due to the season, angle of the sun due to daytime travel, and the fact that caravans and vehicles invariably have the panels horizontal. To say nothing of cloud cover, haze, rain, dust, temperature and a host of other factors which reduce irradiation of the panels.
Your 1kW/m2 is only appropriate at what is called "Peak Sun" which is only achieved when the sun is directly overhead with the panel at a right angle to the sun's rays and a temperature of 25C.
How reflections from "beaches and sand dunes" can reach the face of an upwards facing panel is beyond me and the presence of clouds are more likely to attenuate the radiation than enhance it.

You say….."Some of the best solar panel performance we have ever seen was in Tasmania when the sun shone and the temperature was low." That does not surprise me at all but has nothing to do with supporting your argument.

The real truth is that you may well see peak performance of your solar panels for a short time under ideal conditions during Peak Sun but you will not collect energy at that rate throughout the day. The aggregated energy collection over a day is much less than at Peak Sun. And what is disappointing is that I think you well know that.

Alan, the windy.com figures represent real and current irradiance not theoretical and if you have never experienced significant reflection effects, you need to get out more.
I suggest that you over estimate the horizontal panel losses. It is easily calculated.
The Tassi thing is the effect of reduced temperatures which can allow performance in excess of "standard" and it is a double banger because fridge loads are also lower at the same time.
Cheers,
Peter
OKA196 motorhome

Did it ever work properly?
Cheers,
Peter
OKA196 motorhome

A nearly 200 ltr fridge will pull more than 2.8 amps . BMS? I think you mean a shunt in place that gives a readout of how battery is performing. 200 a/h of battery is realistically only about 140a/h max. You really need to know how many amp hours are used over several hours of running to get a realistic figure. Disregard the solar power for the moment until you can get an accurate figure of how much power is being consumed and the exact capacity of the batteries.

According to the manufacturer the power consumption is 75 watts which is about 6.5 amps at 12.5 volts...lot more than 2.8. If fridge is not very full it will recycle at more often as well. Warm days also see a lot more power consumed.

I,ve got several 90 litre fridges and depending on weather conditions I,ve seen them use 60 amps in a 12 hour period on a hot night.

Without knowing the amount of power being consumed its all guess work. Once the real consumption is known you can build your system to suit. I,ve always believed in doing more. If I had a 200litre fridge I would have 300a/h lithium, 600watt solar and good dc/dc /240 volt chargers.
Good luck.

You have misunderstood the numbers Bigfish.
2.8A AVERAGE current draw is realistic, 6.5A when running. Equals 28Ah for 10 hours and 70Ah for 24 hours (+ weather allowance if hot).
And drawing 6.5A / 2.8A average, a single 100AH AGM should deliver 100Ah before the fridge stops.
Cheers,
Peter
OKA196 motorhome

Craig.
Peter beat me to it!
The AVERAGE current draw will be under a test condition. It might draw 6.5amps when running and the ON to OFF times averages at 2.8. But in hot weather. door opened a few times., has to freeze something or frequently gets warm items replaced into fridge, 188 litres might mean the fridge runs most of the time and that AVERAGE is simply nonsense.
Another situation which affects fridge run times is, if the van is positioned with fridge side to sun that side gets hotter and less cooling for fridge, so it runs more often.
If the batteries are good, the wiring is proper, the fridge isn't being heated, I would FIRST look at the dirty solar panels. As mentioned, flat mounted, dust mud film buildup over a corner, will almost eliminate that panels output. = not much battery power stored.
The Van design may also be an issue. Many vans simply dump heat out from their rear into the fridge enclosure. The fridge sits IN that enclosure and then has to soak up the heat which it has just pumped out of itself. An Endless cycles of heat soak. Unless the sides and top are additionally insulated or the heat is removed from the cabinet by a fan or similar, the fridge is stewing in it's, own juices, so to speak, therefore run times increase. Many vans are not designed to assist fridge performance.

Craig, you need to answer Peter's question.
Is this the first time you have ever tried running the fridge for any amount of time off of the batteries.
Makes a difference, problem may not be a fault but a design problem.

Hey qldcamper, Craig said above that it used to run 3 days no problem, as it’s only 14 mths old thats my guess of the “used to” timeframe.

He sure did Bonz, but look at the time stamps, he answered after I prompted him to.

Hey QC. Cause I don’t know you I can’t make a comment possibly approximating the cleverness of your gluteus maximus but one day I hope to meet you and shake your hand.!! Thanks for the courteous reply ????

Good post Cuppa.
If you are correct (and it does make sense), it would be a seriously undersize cable or it is a long way between the battery and the fridge.

EDIT: you could run new cables between the 2 temporarily to test this solution. Make sure the earth AND the active are both adequate.

EDIT #2: I ask again...... "Did it EVER work properly?"
Cheers,
Peter
OKA196 motorhome

Peter.
I would prefer NOT to use the terms, Earth and ACTIVE. Much prefer NEGATIVE and POSITIVE of the system. This is because there will be an Earth and ACTIVE probably not far from the 12v wiring, but with much more clout!

I prefer red and black.
Dave.

Whatever floats your boat. :)
Cheers,
Peter
OKA196 motorhome

Cuppa
Craig doesn't seem to have mentioned ANY voltage the fridge CUTS OUT at! He is not sure of it all. Where did the stated 125v for his fridge to be CUTTING OUT come from????? Maybe I missed it somewhere but 12.5v seems to be only mentioned by respondents and not the OWNER.
If this is true, and the 12.5v isn't part of the issue then many other problems might exist. Likely only one or two.

Reply 647179.
Cheers,
Peter
OKA196 motorhome

Thanks Peter.
To save you looking , here’s a screenshot RMD.

A brief follow up to Peter's question "Did it ever work properly".

Perhaps a more useful question might be "Did it ever work properly for longer than 3 days when the sun didn't shine much?"

I have the impression that this may be a question which cannot be answered. It is quite possible that there is nothing wrong with the solar & battery side of things, & that the fridge cutting out is a result of the voltage drop I suggested earlier. This may well never have showed itself previously if the batteries had not fallen to 12.5v.

A quick & easy test if Craig can access a battery charger would be to fully charge the batteries & then see whether the fridge works again. If it does, as I suspect it probably will, then voltage drop in the fridge wiring will be confirmed ...... & the fridge will again stop working if/when the battery voltage gets down to 12.5v.

.
I have to endorse Peter g28's answer.

When trouble shooting there is only one sensible way…. Start at the power source and measure and observe, proceeding on a logical basis. It really is useless to suggest "try this" or " try that".

With respect, it is clear that you have no skills in electrical matters and may only come to poor and maybe expensive conclusions by listening to suggestions and dabbling.

As Peter g28 said "go to a qualified auto electrician".

And I make no apologies to those who attempt to assist with erratic suggestions.

Thank gents for all your input much appreciated I’ll see if I can find a good auto Electrician to assist me while I’m in Melbourne as I don’t have the tools ..once again thanks

Allan B
Most replies have not been erratic at all! Simply alerting Craig as to the myriad of things to check. He chose to ask here. He didn't choose to visit an auto electrician, he chose this forum.
If acting with some knowledge of the issue he could possibly find the issue, even without some deep knowledge of electrics.
When someone asks about electrics, there seems a chorus of folk who immediately disregard pretty solid advice and simply say " see an auto electrician" . Not sure why!

If Craig said where he is, someone local with reasonable ability could probably ID or even fix the problem and send him on his way! No! We can't have that could we.?

In this debate...
I am on the affirmative side...

Go see a qualified auto elect because;

The forum member from the outset had to be coaxed for further details info regarding his 12v set up and even then some details were absent, so no disrespect intended, their knowledge of their particular caravan 12v system is....sketchy..
Just some of the details that come to mind for me...

- What is the distance from the battery box his the fridge.. wire run length.
- The wire diameter in the system, is it all the same size..is it different? if so..which part of the circuit?
- Type of shunt and where is it located and what is connected to it? ie what loads are running off it besides the fridge?
- What type of battery monitor is with the van? Brand of monitor?..how is it wired into the circuit?
- What type of 240v Charger has the van got and what amperage?
- Is there a DCDC charger in the system..
- Where the connectors like? wet soldered or crimped, what is their quality like?
- Are the all the connectors suitable to carry the sustained current needed.
- Manufacture and model of AGM Batteries.
- Are the two AGM batteries wired properly in parallel..is one getting more charge then the other or discharging more than the other?
Then there is the myriad of questions about the fridge...

We could be here for a while asking this forum member "check this..check that?"

My vote...get a qualified auto elect with 12v system specialising in caravans to look over the van.

Also I may add, just reading between the lines...
I may be wrong...
Seeing that the van is 14 months old..a recent post Covid release..
My outside guess is that the 12v system for this van was gobbled together with a "she'll be right mate" attitude with a substandard 12v design, condition and hasty assembly..and then the van ushered out the door to this forum member who by the way has been left with a substandard 12v system that when in an "Off grid" situation is left wanting.

On the other hand, the OP has asked for assistance so there is some interest in his solving this himself with some assistance.
If all he ever gets back is "go get someone who knows this stuff" he will learn nothing and will still be paying for help with every minor issue in 10 years from now.

Personally, I HATE electrics with a passion and I claim absolutely no expertise. I am currently building our second rig and, like the first, I insist on doing all the electrics myself as that is the only chance I have of understanding enough to fix those inevitable problems and to make the changes that will be needed over the next years.
Cheers,
Peter
OKA196 motorhome

.
Peter,

You say "Personally, I HATE electrics with a passion".
I must say that I LOVE electrics with a passion. My whole life has been fully and passionately involved with electrics.
Yet so often on this forum when I make an electrical expression it is challenged or refuted by persons with undisclosed qualifications or experience in electrics. Very curious behaviour…. haven't figured it out yet, but then my qualification is in electrics not psychology.
I believe Collyn Rivers to have had a similar experience on this forum.

Peter g28
Sending someone to an AUTO electrician is a referral, not advice as I see it! Affirmative could ALSO be agreeing with the statements provided to LOOK SEE and FIND. Then Craig is armed with more ability to decide a course of action.,,
Much of what you mention, re, the possible causes, is sound.

If Craig looked and realized the wires to his regulator were thin, as I suspect they are, it can explain some degree of loss of ability to charge.
I am with the other Peter with his vehicle build.
Being after the COVID crap. the batteries Craig has, may have been discharged for months at the builders, always charged since, but, "stuffed really" and now at END OF LIFE. A friend bought a 19ft van new and the builder fitted second hand batteries to it. At Gregory Downs, his fridge was behaving just like Craigs. I charged them and they didn't last the night. I said the batteries were cactus, He wouldn't have it! He got across to east coast, an auto elec tested them, = stuffed. After that he was OK with new batteries.
However, the wiring to the reg was too thin, just enough, normal with van makers. Eventually, back home we added larger panels, in series, NEW reg to handle the voltage, increased the cable size from panels to reg and battery. NEVER had a problem with low batteries since.
These factors can fairly easily be identified IF one looks with some knowledge of what IS required. Maybe Craig has more than before and can now workout what is best for him.
Getting an auto electric crowd with integrity, to only do the necessary, is a challenge.

Thank Macca I give a call

Thanks I’m not sure how to check this value this is relatively new to me thank you

Read your user manuals.
More than one of your devices could have settable battery protection like a solar regulator or bms system and ofcourse the fridge itself.
It would be set out in the manuals. If they are set for lithium it will not suit AGMs.
I run a calcium accessory battery and my cut out is set to the lowest the fridge will go, from memory 10.5v.

Ok thank you

.
According to the User Guide for the current models of Dometis 188 litre fridges the low volt cutout is set at 10.4 volts. No adjustment is referred to. Of course, Craig's earlier model may be different.

Incidentally, 188 litre is a large fridge and Dometic nominate a running current of 9.2A with a typical 'average consumption' of 2.8A. This represents a duty cycle of about 30% which is optimistic for typical Australian conditions.

As it appears the fridge has operated satisfactorily in the past then undersized cables etc can perhaps be disregarded and the most likely problem is poor battery performance as Peter said in the very beginning of this saga….. "Either you are not getting the charge you might expect from the panels into the batteries, or the batteries are stuffed."

Craig, you could get a battery supply dealer to test your batteries which they usually will do for free, but the outcome may not reveal the reason for their seemingly premature failure. It is likely to be because the batteries were not being fully charged to the maker's specification or were allowed to deep discharge at some time. If you replace the batteries this matter of adequate charging needs to be addressed or a repeat of the problem may occur to the new batteries. If you do replace the batteries, maybe consider lithium with an internal Battery Management Control which will protect the battery from over-discharge.

I have never seen any 12v fridge which has an adjustable voltage cut out as high as 12.5v.

Thanks Alan
I was considering upgrading with Lithium batteries possibly about 120-140amphr it will on the physical size so they fit the current battery holders thank you

You have hit the nail on the head Allan ,batteries that the problem..

So cuppa,
Your saying it isn't worth a quick look before throwing away several hundred dollars worth of batteries that are only 14 months old and replacing them without any form of system testing.
Reading the operating manuals is the first thing that should be done before asking for advice.
Long live armchair experts on internet forums.

.
Nah 2517, Peter nominated batteries right at the start. I agreed but wanted to see what developed first.
It was the usual shindig!

Batteries usually don't die in 14 months without a very good reason.
Good idea to identify that reason so you don't wreck another set.
Cheers,
Peter
OKA196 motorhome

I believe many of the responders on here have the ability to ID and rectify Craigs problem. The responses will have covered the possibles, but which one it is , has to be found. Some seem offended if their statements are not the ending of the discussion. However, Stating "Yet so often on this forum when I make an electrical expression it is challenged or refuted by persons with undisclosed qualifications or experience in electrics. Very curious behaviour…. haven't figured it out yet, but then my qualification is in electrics not psychology." A very eloquently phased Put Down , aimed at many.

Just because someone effectively demands to know others qualification before any respect is forwarded is purile and condecending. Yes some have MORE qualifications in ELECTRICS or RADIO , OR , OR - but that does not mean others comments are invalid or should be disregarded. There area few ELITES here, if they had a problem outback, would definitely appreciate the ability and experience of quite a few of the responders who HAVE HAD to diagnose and repair. Have you noticed, those with ability seem to not need to ask on the forum????

qldcamper ... I don't understand your response to me, I think you have addressed the wrong person with what you have said. What I have said is quite the opposite & I suggest we may well be in agreement. Suggesting that I am an armchair expert is unreasonable. I am not an expert, but I do think what I have posted, based upon the information supplied is logical. Unlike several red herrings which appear to be based, not on what has been said, but rather upon assumptions.

Allan B, there are a number of ways to commence checking what the problem is, including getting the batteries tested. In my view paying someone to do this does not make sense as a first step, when there are simple & easy checks which can be done prior to this which will cost nothing.

At risk of appearing argumentative I believe your statement "it appears the fridge has operated satisfactorily in the past then undersized cables etc can perhaps be disregarded" has missed the mark. None of us know any more than " When I first brought it I went 3 days without any problems I’ve been been on power for the last 12 months". That being so it is very possible that what you suggest was 'satisfactory operation' in the past never drew the batteries down to 12.5v previously, 3 days in good solar weather could easily have seen the battery voltage remaining above 12.5v ...... and thus it remains perfectly possible that having now dropped to 12.5v, voltage drop between battery & fridge could as previously suggested very well be the reason the fridge stopped working.

Of course Craig could pay to get his batteries tested as a means of confirming or excluding 'stuffed batteries' as the problem. But at no cost at all he could charge the batteries to above 12.5v & see whether the fridge then works again & subsequently observe to see whether it then ceases to work once again when the voltage drops to 12.5v.

I don't understand why you would disagree with this, other than as a result of a possibly mistaken conclusion drawn without sufficient evidence (IMHO) that the system has worked satisfactorily in the past.

.
Cuppa, my nose, and the few facts offered, tell me that a very likely possibility is a battery problem. What's more, it is the easiest thing for Craig to do. And as for your…. "getting the batteries tested. In my view PAYING someone to do this " I actually said "…. get a battery supply dealer to test your batteries which they usually will do for FREE." Once again I am being misquoted… I do wonder if some people read properly or purposely misquote.

Craig said "When I first brought it I went 3 days without any problems" so it would seem that it had worked properly in the past and was therefore unlikely to be an installation problem such as "inadequate gauge wiring".

Regardless of whether "the system has worked in the past" or anything else, I do not think that Craig has any chance of solving the problem himself no matter how much guidance he is given, and that his best way forward is to seek professional assistance.

NOW, you and others put suggestions to Craig and then I also did. Why do you find it necessary to then castigate me if my advice does not support your view. Craig will hopefully read all expressions and make up his own mind on options. At no time did I say that anyone's view was wrong or inappropriate. I merely offered a way forward for Craig.
What is it about electrical threads that brings out the bludgeons?

Oh dear.

I'm sorry you see bludgeons in my post Allan.
No castigating was intended.
I explained why I am thinking as I do.
I innocently expected you would consider what I said & would agree with what I had said.
Instead I feel it is I who am being castigated by you.

Either of us could be correct about the cause of Craig's fridge issues, & as I said I cannot understand why you appear to be married to the belief that all worked well in the past .

I really don't want to argue. I did however want to offer my well intentioned thoughts to someone who asked for help and the only reason I am posting again is not to be the 'more right' than you, but in the hope that it will provide Craig with a balanced forum response when none of us can actually *know* the answer.

I agree that often it is wise to advise folk seek assistance from well informed/qualified folk. But I also think that if we can offer some problem solving strategies which cannot do harm & that anyone can do in the first instance, that it is probably worthwhile to do so. Does it really matter in what order Craig tries to rule out whether it is the batteries or the cabling that is at fault?

Is there an argument to be had about whether the simple test I suggested, or the taking the batteries to be tested by someone else should come first? I think not. But Craig now hopefully has a better idea what his options are & can decide for himself

Trying to help is what forums are about - I'm sure you will agree on that.