How many watts needed from solar to maintain battery w/ Engel fridge

[Rockrunner]

Hello,
I have an older Engel 45 fridge that I want to hook up to a free standing Optima yellow top, I want to keep it charged using a solar panel but not sure how big of a panel I need. I would like to add a single panel to the top of my little camper and keep the fridge plugged in 24/7 over the summer.

Meant to ask how many amps not watts 
TIA for any advice

 

[calicamper]

Look up the fridge stats and put a meter on it do you can track the Amps burned. Then look at 30-40% of the battery rated stored amps , then do the math on the solar needed to both charge the battery and power the fridge.

Hint yellow tops are overrated, over priced and might be under capacity for what you might need.

 

[calicamper]

10watts is equal to a conservitive .5 amps generated in good conditions.

 

[calicamper]

Example
Say your fridge burns 3.5 amps an hour. Just to power the fridge you need 40-60 watt capability. But over night you burn off 4x12=? Amps burned over night that you need to put back into the battery in say 4-5 hours peak solar time.

Amps are you friend, figure out how many you burn and how many you need to create and you have your solar sizing answer.

 

[Rockrunner]

Thanks guys,
I have a marine battery too but the Optima fits the area better. I can and will add a "charging" cable from the motor so it will charge when driving but want to keep it cold while the vehicle sits during the week. Was hoping to get away with a 15 watt solar charger mostly due to size just not sure that it will be enough. Looks like the fridge uses about 2.1-2.3 amps per hour and should be a little less during the week since it won't be opened and will stay cool. The problems is the ambient temperature and the fridge keeping up with it.

So so if I have the math right at 2.2 amps x 10 watts I need a 40-50 watt solar set up. The battery I may end up using is rated at 23 amps for 200 minutes so at 2.3 amps draw I should have 2000 minutes??? Am I figuring that right? So that would be about 33 hours, however I have had my fridge in my truck before for 48 hours and not killed the battery.

Time me to do some more research on panels and how fast they will recharge a battery. Any ideas are very welcome, I can build rigs but electrical is not my strong suit.

 

[calicamper]

23amps is really small, you can only figure about 30-40% max of your rated amps given batteries cant be run empty. 50% is more or less dead battery with typical deep cycle batteries.

Most folks report using 75ish amp batteries with 40-80 watt panels and report success being off grid for a week with the fridge going.
You need a solar controller too so the battery is managed. The small simple controllers 20-30 amp controllers like the one I use even have an ouput side, that could be used to power the fridge and cut power at 11.5volts to prevent killing the battery. If its being left for a week unattended thats probably a nice feature to use, so your not killing the battery if its cloudy or for whatever reason it didnt gain enough charge during the day.

 

[plh]

Roughly a 100 to 125 watt panel should suit your needs. And a Group 34 or 31 deep cycle

http://www.amazon.com/Odyssey-31-PC2150S-Heavy-Commercial-Battery/dp/B002498NR2

http://www.amazon.com/Odyssey-34-PC1500T-Automotive-LTV-Battery/dp/B00249CSS2

 

[1Louder]

Lots of info a few threads down: http://www.expeditionportal.com/forum/threads/157638-How-is-everyone-powering-their-portable-fridges

http://www.arkportablepower.com/blo...reezer-and-battery-life-what-you-need-to-know

 

[FLEXOPOWER USA]

Hi Rockrunner
Based on our experience with 2.000+ clients who face the same question what size solar array needed to sustain the operation of a fridge, in your case you want to run it 24/7 during summer, you most likely will be looking at 158W or more. Less and your battery will be discharged in 1 week. That is during days with sun.

For days without sun (overcast, rain etc.) your fridge will run from the battery solely and you need to consider how many days autonomy you want as this will determine how many batteries you would need to install. Example: if your fridge draws an average of 3A/h and you have a 100Ah deep cycle battery, after 24h total load drawn is (24 x 3Ah) 72Ah and your battery would be 72% discharged (not counting battery losses), i.e. empty.

If you frequently open and close the fridge the suggested 3A value will increase.

Our suggestion would be to ensure the vehicle is parked in the shade (cooler for the fridge and vehicle), whilst the solar panels are in the sun. Size wise you should consider a 158W array more and avoid partial shading. On the battery side you should consider at least 2 x 100Ah deep cycles (parallel) to have 2 days autonomy.

For more reading, there are some relevant posts on our website

 

[teotwaki]

Where are you located RockRunner? The amount of sunlight you can expect will be a factor in your panel size. For instance, in SoCal I get by with a high quality 60W panel. I also have an older fridge. (Engel 45)
I use a Bosh Marine deep cycle battery charged through a CTEK 250S Duo. The Duo is overkill for what you want and I paid less than half of current list as I recall

 

[teotwaki]

Forgot to add in a few other comments:

My Engel has the insulating cover.
Total amp-hours depends on how cold you set the fridge too.
Mine pulls about 2.5 Amps for 30 minutes out of the hour so that is 1.25 Amp hours
Typical running totals are 20 A/H per 24 hours

If I get great sun from 8 AM to 4PM then 20A/H over 8 hours is 2.5Amps from the Solar panel per hour in a perfect world. Solar charging never works perfectly so having a panel bigger than calculated is needed due to a number of factors which is why a 60W panel works well for me. If North Carolina has less sunshine it might be that 158W of panels is needed.

Solar Blvd has awesome prices on everything that you need.

http://www.solarblvd.com/

60W panel is $78 https://www.solarblvd.com/product_info.php?cPath=1_269&products_id=2672

6 Amp charge controller for $42 https://www.solarblvd.com/product_info.php?cPath=6_48_100&products_id=635

 

[LandCruiserPhil]

Many factors to consider -
Ambient temp where the fridge is located
Temp setting of the fridge
How full is the fridge
Does the fridge have an insulated wrap
Where are you located
Time of year
Panel angle if any


That said I have gotten by with a high quality 60watt panel in ideal conditions. I would not go smaller than a 100 watt panel if you leave in the sunnier south western states.

 

[jonyjoe101]

the engle 45 looks liked the edgestar fp430 i use to have. When set to 40 degrees and in excellent weather, I use to run it 24/7 for months at a time off a 120 watt panel and a 75 ah agm battery.
When hooked up to a dc wattmeter, the fridge used about 26 amps over a 24 hour period. The bigger the battery, the more reserve you will have for cloudy weather.
Even a 100 ah battery wont last you 2 days of bad weather, you want to not drain your battery more than 1/2 to last you longer.

 

[stingray1300]

Hint yellow tops are overrated, over priced and might be under capacity for what you might need.

.
I'm glad my experience with Yellow Tops is different...
.
I got a free 53watt solar panel, and so far it has served the need. But I did get in on the Renogy group buy (TacomaWorld) for a 100watt suitcase (dual panel) unit. The numbers that we've come up with say that it will be more than enough to remain autonomous as long as we want as long as we have 6-8 hours of good sun per day to keep the ARB Fridge happy.
.
Another consideration is how much food do you carry? What I mean is, we find, that in our case, we're really never off grid for more than 3 days at a time, because we move sites, and always restock the fridge at a grocery. Just a thought...

 

[Martyn]

Looks like peoples answers are all over the place here. I'll add to the confusion.

We tested the power consumption of the Engel fridge over ten years ago, we ran the test for a period of three months, taking daily reads of outside temperature, inside temperature and we use a Doc Wattson to track the power consumption and get some controlled environment data.

Our in field experience has shown that a good 60 watt solar panel (Aspect Solar or Powerfilm) will produce enough energy in a 24 hr period to run an Engel 45 indefinitely in the continental US. In all cases we paired the solar panel with a group 31 battery to act as a reservoir for energy and to power the fridge overnight.

We did the same experiment with the National Luna 50L fridge and got the same results. When ARB launched there own fridge we asked to test the fridge side by side with the Engel and the National Luna for a three month test, at that time ARB declined our offer so we have no data on that fridge.