Solar Panel - 2x Batteries - National Luna Fridge

Post by **Royco** » Mon Feb 07, 2011 12:00 am

After reading the "LED Strip light Test" post, I thought I'd post a test that I've been meaning to do for a while now...

I want to see how long my fridge can run on two batteries connected to the solar panel.
I know this is a theoretical test as the house is a lot cooler than a tent(!!), the fridge gets loaded with warm items and gets opened often...

My setup is the following:

• 90w Solarworld Solar Panel (5.1amp output)
• Phocos CML10 10A solar regulator
• 2x Deltec 105Ah Deep Cycle batteries
• National Luna Weekender 50-Twin

This is how I started:
The panel is not always in direct sun, I attached it on the pergola where it gets midday and afternoon sun.
I did not charge the batteries, but they are new and with no load, were reading at 12.8v.
The fridge was running off the 220v for 2 days prior to connecting the batteries, and the lid is cabled tied to prevent it from being opened.
The two batteries are connected in parallel and the fridge is connected directly to one of the batteries, not to the regulator.
I have a temperature gauge that I was going to add to the test, but that seems pointless as the fridge temperature will always remain within 3 degrees.
The fridge has been set to zero and the freezer is 10 degrees lower (ie -10)

I connected the fridge to the batteries and removed the 220v yesterday 05 Feb 2011 at 19:00.

Any questions or comments will be gladly received...

Post by **Royco** » Mon Feb 07, 2011 12:10 am

Here is a pic of the battery boxes:

This is the thermometer. I have a sensor in the fridge (top reading) and one in the freezer (bottom).
I love this gadget as I know what my fridge is doing in the back of the bakkie while we're driving and I know it's working (or not!) while we're camping

Reading of the batteries on 05 Feb 2011 at 19:00 connected to the fridge but the compressor was not running.

Post by **Royco** » Mon Feb 07, 2011 12:16 am

Reading of the batteries 06 Feb at 20:00

I take the reading when the compressor is not running - that means the fridge is at zero degrees.
I'm not too sure how "scientific" this exercise is ... but I'm hoping it will give me a good indication of how long we can use the fridge on the two batteries.

OOOOMS · Post by **OOOOMS** » Mon Feb 07, 2011 12:59 am

Roy, x2 questions
1) is there anything in the fridge?
2) Why keep the door sealed? Surely if you are camping you are going to put things in and take things out.

or maybe with the next test you can experiment and compare. Will be interesting comparing even putting the fridge in direct sun where it will work quite a lot harder

Looking forward seeing the result

Post by **Royco** » Mon Feb 07, 2011 1:15 am

Besides the two sensors, there is nothing in the fridge.
The reason why I wanted the lid sealed was to limit the variables for the test.
For example: what went in? what was the temp of the item? How long was the lid opened and how many times?

I like your suggestion to have a comparison test - but maybe I'll do that test "in the field"

OOOOMS · Post by **OOOOMS** » Mon Feb 07, 2011 1:21 am

Perhaps the next test should be something you would 'do in the field' to better understand what the impact would be opening and closing the lid and putting in consumables.

Not exactly sure what the point is having a fridge not opening the door with nothing inside?

FUDGES · Post by **FUDGES** » Mon Feb 07, 2011 6:30 am

Me also don't understand the point of the test?

What will you do with the results? For me there's no comparison to "in the field" test or are you going to use this test as the control?

Post by **CasKru** » Mon Feb 07, 2011 7:20 am

If I understand the test correctly, Roy is trying to determine what is the longest time he can run the fridge for under ideal circumstances on just the two batteries and solar panel. If for instance he can run this setup non stop and the batteries never drain or a month (arguments sake) then the batteries had enough. So if the latter is true he might want to rethink his setup but if the first one is true... he should be sorted. (well this is what I think he is trying to determine)

Post by **Royco** » Mon Feb 07, 2011 7:52 am

Thanks Cassie, that's pretty much what I'm trying to see.
I need a bench mark to know what the ultimate limit is.
If I add items to the fridge, like warm water, and expect it to freeze, there are far too many variables that add to the equation.
If the batteries only last 2 days in this test - then I have a serious problem...

The idea is more to test how the solar panel can assist the battery life, with a steady current draw, rather than testing what the fridge draws.

warrenaken · Post by **warrenaken** » Mon Feb 07, 2011 8:18 am

Where did you get the thermometer? how is it linked to the sensor?
Thanks

Post by **Royco** » Mon Feb 07, 2011 8:30 am

The sensors are wireless.
I bought it from:
http://za.rs-online.com/web/search/sear ... R=712-1110" onclick="window.open(this.href);return false;

One thing I found, alkaline batteries do not work when frozen.
Lithium batteries work well in low temps.

arnize2 · Post by **arnize2** » Wed Feb 09, 2011 4:58 pm

Roy, hoe gaan dit met jou toets?

Post by **Royco** » Wed Feb 09, 2011 9:09 pm

Glad nie goed nie!! :evil: :evil:
7 Feb 20:00 12.42v
8 Feb 20:00 12.34v
Then I pulled the plug - literally!

According to what I've learnt about deep-cycle batteries, 50% SOC (State Of Charge) is around 12.2v ! :problem:
And every time the batteries get discharged this low, it reduces their life span.
So to save my batteries - I stopped the experiment.

But over the 4 days, the average was just under 0.2v loss per day.
I also think my panel did not get enough sun ... at least I hope I can improve these figures.

I left the panel connected for today and at 20:00 the battery reading was at 12.61v.
I've now put them on charge.

I must admit I'm not very impressed... and with 2 batteries nogal !?!?
But I do think that the position of the panel is very important - well, that's what I'm hoping!!
I still have my dual battery in the car that I could also use when camping - but damn :!: three batteries and a solar panel to only last a week

I'll get the ultimate setup yet......

zepplin · Post by **zepplin** » Wed Feb 09, 2011 9:43 pm

What about one panel per battery?

Post by **Royco** » Wed Feb 09, 2011 9:53 pm

I was hoping that a 90w 5.1a panel would supply enough juice to run my fridge... :alvarin:
Maybe you're right....

:!:

OOOOMS · Post by **OOOOMS** » Wed Feb 09, 2011 10:08 pm

zepplin wrote:What about one panel per battery?

That is a solution, if you have the space, 2 x 90w panels are going to take up you whole roofrack.
Need a larger or another regulator prob. to handle the Amps

Good test though at least you know

If you open and close the lid/lids you use more power.
The temp in the back of the canopy is a lot hotter and requires the fridge to work a lot harder, draining the batteries quicker.
If you stock up the fridge it adds additional load to the batteries

Another problem, no offence but the weekender NL ain't ideal for long stays as it works harder and the insulation is thinner than that of the more expensive NL units.

Adding a fridge cover will also help.

On the positive side, doing additional driving will help the batteries recover(but just assists and you have to do quite a bit) it's been discussed here a number of times.

arnize2 · Post by **arnize2** » Thu Feb 10, 2011 10:08 am

Dankie Roy. Alhoewel ek niks gese het aan die begin van jou toets nie, het dit vir my sin gemaak. Ek het n 40liter Engel, wat ons vir n vrieskas gebruik, en n 45liter Camp Master wat ons vir n yskas gebruik. Die Camp Master word net van 220v af gebruik. Indien ons in die veld kamp gebruik ons die "blou goed" om hom koud te hou. Dit maak dat die vrieskas net 2x per dag oopgemaak word. Ek het net n 40w sonpaneel wat op n staander gemonteer word om die maksimum son te benut. Die vrieskas moet maar bestuur word, maar die stelsel het nog gewerk tot sover. Wat het ek uit jou toets geleer: 1. Son moet optimum benut word. 2. Een reguleerder, Een sonpaneel, Een battery. 3. Die yskas/vrieskas kan nie 24uur per dag aan gelos word nie.

Post by **george** » Thu Feb 10, 2011 10:31 am

I am not to clued up about all this charging things,but i also need to plan my setup.
i understand that a 90watt panel is not going to be sufficient for x2 Freezer/fridges and 2x batteries.
But in Roy's test he only had 1 fridge and 2x batteries.If he only connected the one battery would it have worked better?
The clever okes always explain the electrical like a water setup that actually makes sense to me.
So I think my question is why would 2x batteries make a differences to charging if you only have one fridge connected than appose to 1 battery.
i hope this makes sense

arnize2 · Post by **arnize2** » Thu Feb 10, 2011 10:40 am

Jou vraag maak baie sin George, maar ek het nie n "clue" nie. Al wat ek weet is dat my seun 3 sonpanele ( 90w, 45w, 40w ) en 2 batterye het, maar hy sukkel, terwyl ons heel rustig regkom.

Post by **Royco** » Thu Feb 10, 2011 10:52 am

It might be worth another test, but I've packed up the panel now... will have to wait ...!!
I also think that every panel, regulator, fridge and even battery combination of each person will differ.
So this test would only show me what mine can do (or can't!).

It also comes to what Mark and Arno say about "managing" the fridge - limit the opening, keep it covered, not running it 24 hrs etc - and all of those personal preferences will either make the holiday enjoyable or really frustrating!! :evil:

Mr_B · Post by **Mr_B** » Thu Feb 10, 2011 11:08 am

Roy thanks for taking time to do this test, as Arno has indicated the exercise was not a waste, I for one have learnt a little bit more about the use of solar panels in the field. I wonder how well it would work with one battery and one panel, or does the fridges current draw necessitate a 2 battery setup. Just as a base for your experiment, how long can 2 fully charged batts keep the fridge going before the batts reach the 12.2V threshold, then you could calc how much extra life the solar panel is injecting, like 1 days worth...

Niel · Post by **Niel** » Thu Feb 10, 2011 11:17 am

I normally switch off the fridge when going to bed (late) and then on again the next morning, during the day the solar panel(90w) does its job. To date the battery stay full and the fridge is opened regularly.

I will leave the fridge on 24/7 and then run the panel during the day and see what happens (when camping again)

Post by **Royco** » Thu Feb 10, 2011 11:19 am

Mr_B wrote:Just as a base for your experiment, how long can 2 fully charged batts keep the fridge going before the batts reach the 12.2V threshold, then you could calc how much extra life the solar panel is injecting, like 1 days worth...

I'll try that test next week. Just need to get the batteries charged, and start the fridge at the same temp as I did with the last test.

Is the 12.2v 50% of the SOC? It's what I read on one website, but none of the sites seem to confirm with each other... other sites state 11.4v :wth:

OOOOMS · Post by **OOOOMS** » Thu Feb 10, 2011 11:26 am

It also comes to what Mark and Arno say about "managing" the fridge - limit the opening, keep it covered, not running it 24 hrs etc - and all of those personal preferences will either make the holiday enjoyable or really frustrating!! :evil:

100% correct! What I have done / found out on many trips is (and this pertains to the freezer side of the fridge) when packing meat (obviously vacuum packed) pack it in layers. Between each layer, sufficient newspaper. Not only does this make it easy taking frozen meat out (the plastic tends to stick to each other) but helps prevent the cold air getting out :!: NB....this is very important.

On trips, I am the only one person that operates opening and closing the freezer. Open quickly, take out what you need and close!!! Limit this and you will be OK.

Lowering not necessary switching off as Niel mentioned also helps the life of the battery

Mr_B · Post by **Mr_B** » Thu Feb 10, 2011 11:32 am

The other question is, is your solar panel putting out as many amps as it's specced to? Can one measure the output to make sure? From experience I often seen specs exaggerated!

OOOOMS · Post by **OOOOMS** » Thu Feb 10, 2011 11:40 am

Mr_B wrote:Roy thanks for taking time to do this test, as Arno has indicated the exercise was not a waste, I for one have learnt a little bit more about the use of solar panels in the field. I wonder how well it would work with one battery and one panel, or does the fridges current draw necessitate a 2 battery setup. Just as a base for your experiment, how long can 2 fully charged batts keep the fridge going before the batts reach the 12.2V threshold, then you could calc how much extra life the solar panel is injecting, like 1 days worth...

Starting with two fully charged batteries like in this experiment 2 x 105aH will help, however the solar panel only produces (I assume on average 5.1aH) 5.1aH is usually only an average calculated from sunrise to sunset. So at 07h00 you may only be getting 1aH and 12h00 maybe 8aH. eND result is x2 batteries only prolong the dying effect

Niel · Post by **Niel** » Thu Feb 10, 2011 11:44 am

B, when looking at the regulator it seems to come close. Here is the spec of my 90w

Post by **Royco** » Thu Feb 10, 2011 11:47 am

Mr_B wrote:The other question is, is your solar panel putting out as many amps as it's specced to?

Gee I hope so!!

The sticker on the back is the only thing I can go on... another reason for this test!

IF my calculations are correct:
Fridge: 2.5a x 24 hrs = 60a draw
Panel: 5.1a x 6hrs = 30.6a input (6 hours because of the location of the panel - not optimal)

So the panel will not be able to supply ALL the current needed....
Exactly as Mark has commented...

OOOOMS wrote: eND result is x2 batteries only prolong the dying effect

So my never ending power supply setup still needs work

Mr_B · Post by **Mr_B** » Thu Feb 10, 2011 11:56 am

Royco wrote:So my never ending power supply setup still needs work

You been watching too much Big Bang Theory!

OOOOMS · Post by **OOOOMS** » Thu Feb 10, 2011 12:23 pm

Just a simple question....

Where would you set up camp?

A:

: thumbnail.aspx1.jpg (4.07 KiB) Viewed 3876 times

B:

Mr_B · Post by **Mr_B** » Thu Feb 10, 2011 12:28 pm

Take a swimming pool net pole with... attach solar panel to pole... hoist panel above trees... secure pole to trees...

And found out the cables are too short... :wink2:

OOOOMS · Post by **OOOOMS** » Thu Feb 10, 2011 12:34 pm

Exactly Mr B.....10/10

You camp in the shade under the tree....B!

So how effective is the panel then?

or

If you camp in the sun, how much extra does your fridge then have to work to keep it cold and then still in the back of the canopy or trailer?

Post by **Royco** » Thu Feb 10, 2011 12:35 pm

That was exactly our "problem" in December!
We had a FANTASTIC camp site... all in shade!!
I don't like taking the panel off the bakkie roof, and we use the tail gate as our kitchen table.
:wth: :wth:
I don't know! I ended up driving the bakkie into the sun during the day +- 50m away from the tent to get full sun... then, does the fridge stay in the tent switched off, or in the boiling bakkie, but running?

I only had 1 battery in Dec...

What seemed to work, was taking the fridge with the bakkie...
:wth: :wth:

Post by **Royco** » Thu Feb 10, 2011 12:37 pm

Mr_B wrote:Take a swimming pool net pole with... attach solar panel to pole... hoist panel above trees... secure pole to trees...

... and then the wind starts to blow... and tents start flying past you, while you watch your panel ... :evil: :evil:

OOOOMS · Post by **OOOOMS** » Thu Feb 10, 2011 12:41 pm

And then all you need is 2/3 day's of rain......rain.....rain.....

Post by **george** » Thu Feb 10, 2011 12:44 pm

National Luna Weekender 50-Twin

Roy have you measured the currant that the fridge draw?
And the actual amp that the solar panel supply.

Niel · Post by **Niel** » Thu Feb 10, 2011 12:47 pm

I have an 8m extension cable to connect the panel to the batteries. I mainly use that to charge the high cycle's in the trailer. The panel is kept on the roof rack.

Post by **Royco** » Thu Feb 10, 2011 12:54 pm

george wrote:
National Luna Weekender 50-Twin
Roy have you measured the currant that the fridge draw?
And the actual amp that the solar panel supply.

Nope, purely taken from the spec sheet.
So I guess their marketing figures are not what I am experiencing.

Mr_B · Post by **Mr_B** » Thu Feb 10, 2011 1:05 pm

Get a wireless solar panel!

Post by **george** » Thu Feb 10, 2011 1:12 pm

Royco wrote:
george wrote:
National Luna Weekender 50-Twin
Roy have you measured the currant that the fridge draw?
And the actual amp that the solar panel supply.
Nope, purely taken from the spec sheet.
So I guess their marketing figures are not what I am experiencing.

I just watch the shootout of fridges by ASPW and accoring to his test the NL 40lt uses 3,5 amps.
But thats when its running and clearly your fridge was not running all the time.So me think that the solar panel is not producing what it should :problem:

Mr_B · Post by **Mr_B** » Thu Feb 10, 2011 1:29 pm

George, the panel probably does produce what it should, but only in ideal conditions... being direct sunlight. The panels were only getting this for 6 hours, and the output drop is quite steep in shaded conditions! I guess if you could get 10 hours direct sunlight, the effectiveness would increase dramatically!

SuidWes · Post by **SuidWes** » Thu Feb 10, 2011 1:30 pm

Thanks for sharing your test and results Royco

I also still need to perfect my setup... I've got one 60w panel connected to a 105 H/cycle bat running a 40 litre Engel and some lights when needed. On average I can easily manage 2 days(3 nights) on the sytem without adjusting the panel every 30 mins :) And if I need another day I connect the fridge to the vehicle's main battery while the solar starts to recover the 105 H/cycle.

Some findings/tips:
1. The bat lasts longer if the fridge is not on a slide as it makes it difficult for anyone else, SWAMBO, to open and close the unit :razz:
2. Freezing the meat on 220 3 or 4 days before the trip is vital and once on 12v I keep the fridge temp on zero (Setting 2 on the Engel) and this keeps the meat frozen and the beers cold :) It also helps to put a piece of cardboard between the frozen and non frozen stuff.
3. A vent on the canopy makes a huge difference.
4. A protective bag also insulates the unit and is worth the money. I've added some newspaper between the bag and unit I think it helps. Also handy to have newspaper on trips

5. The Steca solar controller I use cuts out as soon as the dual bat system kicks in so not assisting with charging whilst driving.
6. Better to have a mobile panel compared to moving a vehicle around in the sun.
7. Very important to keep the panel glass clean and to ensure zero shadows on the panel...

Post by **CasKru** » Thu Feb 10, 2011 1:48 pm

What I'm wondering now is when you install a dual battery system in your bakkie you have to install an isolator switch. If you don't do this the alternator is not able to charge both batteries at the same time. Now I'm wondering with this test, didn't the same thing happen? Maybe the setup will actually work better with an isolator switch or one battery only. Does this make any sense?

Mr_B · Post by **Mr_B** » Thu Feb 10, 2011 2:10 pm

CasKru wrote:Maybe the setup will actually work better with an isolator switch or one battery only. Does this make any sense?

Eso es exactamente lo que he sugerido antes ... tratando de cargar las baterías a la vez podría ser superior a la capacidad de los paneles!

Post by **CasKru** » Thu Feb 10, 2011 2:15 pm

Mr_B wrote:
CasKru wrote:Maybe the setup will actually work better with an isolator switch or one battery only. Does this make any sense?
Eso es exactamente lo que he sugerido antes ... tratando de cargar las baterías a la vez podría ser superior a la capacidad de los paneles!

Pido disculpas Mr_B .... Acabo de escaneado en el puesto en realidad no los lee. Mi mal. La próxima vez que me ve me puedes pegarle

Maddoglips · Post by **Maddoglips** » Thu Feb 10, 2011 2:21 pm

Guess it time for some to take their MEDS

Post by **george** » Thu Feb 10, 2011 2:33 pm

Roy i hope you not minding hacking your thread a little.
I managed to measure my Engel 40lt fridges amp usage.This is after i blew a couple of fusses

It looks like the amps is about 2.7 and it is now falling to about 2.65.I am going to attempt to do some calculations.
Let say the fridge reached it desired temp than let say very conservatively the compressor will will run half the time.
This will amount to let say 1.5 amps an hour.So in a 24 hour cycle this will be then 36 amps you will consume in a day.
So if you have only 8 hours of sunlight your Solar panel will have to produce 4.5 amps constantly during the day.

Post by **Royco** » Thu Feb 10, 2011 2:42 pm

So then the question is whether the panel will produce 4.5 amps constantly.
And unless 100% perpendicular to the sun's rays... it's still only a theoretical specification or maximum obtainable.

Nope this is not hijacking the thread at all!
The Spanish may be questionable

Post by **george** » Thu Feb 10, 2011 2:52 pm

Royco wrote:So then the question is whether the panel will produce 4.5 amps constantly.
And unless 100% perpendicular to the sun's rays... it's still only a theoretical specification or maximum obtainable.

Nope this is not hijacking the thread at all!
The Spanish may be questionable

Roy I think you need to do some research on how much your fridge draw.
I googled a bit on the Engel 40 Lt and the figure of 36 amps a day sounds ok for a ambient temp of 25 degrees.

Lately I have been camping in 30-35 degrees and my battery on its own does not last a full day

I used an 80 amp battery so effectively I can only use 40 amps.So it actually makes sense to me now that the battery on its own wont last a day.

Mr_B · Post by **Mr_B** » Thu Feb 10, 2011 2:56 pm

CasKru wrote:
Mr_B wrote:
CasKru wrote:Maybe the setup will actually work better with an isolator switch or one battery only. Does this make any sense?
Eso es exactamente lo que he sugerido antes ... tratando de cargar las baterías a la vez podría ser superior a la capacidad de los paneles!
Pido disculpas Mr_B .... Acabo de escaneado en el puesto en realidad no los lee. Mi mal. La próxima vez que me ve me puedes pegarle

Le pega ... Prefiero swing con usted ... que es mejor parar, más vamos a tener problemas "fuera de tema" seguro!

Post by **CasKru** » Thu Feb 10, 2011 3:09 pm

B.....

Offtopic

Niel · Post by **Niel** » Thu Feb 10, 2011 3:51 pm

Does the battery technology also play a roll - charging cycle of the deep cycle?

arnize2 · Post by **arnize2** » Thu Feb 10, 2011 3:54 pm

N "wireless" sonpaneel sal die idiaal wees, maar aangesien dit nog nie beskikbaar is nie en ek nie Spaans (nonsens ) kan verstaan nie, die volgende : Ons kamp in die skaduwee sover moontlik. Mens kan nie die son optimaal benut indien die sonpaneel "fixed" is nie. Ek vervoer myne los met n 10 meter kabel en die staander deur my swaer gemaak. Oujaarsaand het ons by Matjiesvlei naby Calitzdorp gekamp in n windstorm wat tente (selfs daktente ) platgewaai het. My sonpaneel het stewig bly staan

Die opset links is myne en die een regs my seun. Sy panele is "fixed".

Mr_B · Post by **Mr_B** » Thu Feb 10, 2011 4:00 pm

Arno I like!

All you need now is a auto-tilt-swing motorised base on the top of the support pole... with a sun position detector... then you won't have to adjust it every half hour!

Come on all you clever electronics junkies... now there's a gakgat idea!

arnize2 · Post by **arnize2** » Thu Feb 10, 2011 4:29 pm

Mr_B jy is snaaks

Ek kan nie wag om n naweek saam met jou te kamp ( lag ) nie.

Mr_B · Post by **Mr_B** » Thu Feb 10, 2011 5:11 pm

As *a* praat 'n siekte was... I'm a lot quieter in really life...

OOOOMS · Post by **OOOOMS** » Thu Feb 10, 2011 5:39 pm

arnize2 wrote:Mr_B jy is snaaks Ek kan nie wag om n naweek saam met jou te kamp ( lag ) nie.

Nee....jy willie rerig nie.......

Post by **Royco** » Tue Feb 22, 2011 10:01 pm

As Cassie AND Mr_B suggested, I ran the test without the solar panel, just off the 2 batteries.
The fridge draw was exactly the same as the previous test, because it was never opened.

19 Feb 19:30 - 12.95v
20 Feb 19:30 - 12.56v
21 Feb 21:00 - 12.38v
22 Feb 19:00 - 12.27v
Total voltage loss over 4 days was 0.68v
Previous test WITH solar panel, the loss was 0.5v

Not the result I was expecting :evil:

Lessons learnt:
1. The panel must be in full sun from dawn to dusk (in this test it wasn't)
2. If you believe you have a good thing, don't try to prove it! :evil: (ignorance is bliss)

Thanks for all the suggestions and advice.
I will do this test again (one day) with the panel in full sun - once I get a stand like Arno has.

Post by **george** » Wed Feb 23, 2011 8:22 am

Roy at least you know your batteries are 100%.
I dont have experience with solar panels yet,but surely your panel should have produced more power even if it was not in direct sunlight all the time.Maybe you should get a controller that shows you how much amps the panel is producing.

SuidWes · Post by **SuidWes** » Wed Feb 23, 2011 9:22 am

Something is wrong....

I only run a 60 watt panel and when connected, and panel is in the sun, I can clearly see it on the NL bat monitor as it will show a voltage increase of about 3 led's.

I'll also run some tests and share the results...