100+ ambient Temp - ARB 50qt - 100 watt solar panel - Not enough?

[dstock]

So here's the scenario:

We were out in the desert parked for 4 days in 90-107 degree temps this past weekend.

My setup: Dual Diehard Platinums with a NL Split charge system under the hood, 100 watt solar panel/controller, ARB 50qt fridge in the back with 10 gauge dedicated line through Blue Sea fuse panel attached to Aux battery. Fridge was in the back of the JK and windows were vented but not all the way down as we were not near the vehicle for large portions of the day. Partial shade provide by trees and RTT.

The short of it is, the solar panel was not enough to keep up with the fridge during the day and I ended up running the JK about 30 mins per day to get enough charge to maintain. I had the fridge set to 27 which seems to be more like 33 realistically. As the day would go along, temps would start rising and fridge would start moving up to about 35 on the panel. Granted we were swapping out warm drinks for cold ones but we tried limit the amount of times we were opening the fridge.

Since we like desert camping, I am looking on ways to improve this setup. Most likely it won't be in 100+ temps but still I would like to be better prepared. Had we been able to keep all the windows down, might have helped a bunch, not having been in those temps without moving for several days, I just don't know.

Thoughts of ways to improve things:

-ARB Transit bag
-Change out 10 gauge wiring for 8 gauge
-Bigger solar panel
-Fridge on a slide so it could get more air when possible.
-Yeti 400 and panels as backup

Maybe I am dreaming for a solution in these kinds of temps but thought I would throw it out there and see what you guys think

Thanks in advance.

 

[fourstringfletch]

Were you monitoring battery voltage? All machines have limits, and perhaps maintaining a 70 degree delta T while introducing warm drinks is near the limit of this fridge.
I'd like to confirm that the problem was not enough available amps rather than inadequate heat transfer speed.

 

[dstock]

Voltage on the aux battery got down to about 11.4, possibly further overnight, I'm sure I pushed it too far which I won't do in the future. The ARB was set to LOW on the voltage cutoff which is 10.1 volts which is way too low. I will keep it at the MED in the future which is 11.4 so as not to run down the aux battery to the point where I will do damage.

 

[unseenone]

What is the advertised power consumption and size of your fridge. I have an Engel 32, and I live in TX. Without solar in the summer I have been able to keep it running in the back of the vehicle all summer long. But, it needed just a little more to not over discharge the battery, I am just in the process of adding solar, and an additional bigger fridge when I need it. Both have transit bags, as an absolute requirement.

I just ordered a DC inline power monitor so I can actually get some real data for kicks. When not in the vehicle, both units run on solar or AC, but right now just solar to test the setup. I have way more battery than I need, for the house, because I wanted the ability to run more stuff (800ahr)

These fridges are not like house fridges, they work slowly. If there is a bunch of kids opening it a lot, it will take it's toll. For example, the 72L freezer section was half full, I loaded it the rest of the way with unfrozen meat. It went from 5 F to 15 F, likewise, I added 8 glass bottled cokes to the fridge side, and the temperature went up. It will take some time to freeze / cool and then maintain it. The unit will have to work harder to do that. When I loaded the freezer, I removed the 2 gallon frozen water bottle (ozarka) used to fill the empty space. You can do something like that as well.

Depending on the length of your power run, #10 might work, or #8. A quick way to determine if you measure the voltage at the battery, and at the end of your power line. Is there a voltage drop? If you are running 10ft or more you might even have to go to #6, you should do some of your own testing with a multimeter to see where you are at.

What is your solar setup?
what kind / type / configuration of panels are you using?
Why can't you add more panels to the solar to increase your charging rate?

If you have 1 decent 100w panel, you might get 3-5 amps on average charge rate. That is about what the Engel uses (3). So, when the fridge is running, and solar is charging, it might be 3 amps minus charge amps, let's say 5, means only 2 amps are going toward charging. This is an oversimplified explanation, just trying to give you an idea.

My mobile setup, if it helps..
http://www.disco3.co.uk/gallery/displayimage.php?album=lastup&cat=11463&pos=2

You might also consider the possibility of either a higher efficiency fridge, or two smaller ones, so you do not have to open it as much. Also, the fuller the fridge, the more efficient it should be. Empty space is harder to keep cool.

 

[dstock]

Advertised power consumption for the ARB 50qt is .7 to 2.3 amps and I have 1 100 watt solar panel with charge controller built in, I will have to do some tests to see what I am actually getting out of it.

The voltage drop test is a good idea, my run is about 10 feet to the battery, so I will have to see how much I am losing.

This is the first time I have had an issue, usually the fridge sips power but the temps at night were still in the 90's so I'm thinking I am just expecting too much.

Still with some testing, possible wiring upgrades, the insulating cover and better fridge habits I'm hoping to improve things a bit.

 

[unseenone]

I'd be real interested in the results of all of the above. Keep us posted~!!

I know that I need to replace my main power run, I know that I have a voltage drop, of 0.5v This is lost to resistance in the wiring, it is "consumed" in the wiring, or wasted whatever you want to call it. To eliminate that, or reduce it as much as possible, bigger wiring will help. I doubt you have much if any with what you have, but it is worth a look.

I think what you will find is that at best, you're averaging more than the solar is putting out, at least as you are currently configured, hence the backwards slide.

I would also consider a more serious solar setup, so that you can deploy extra panels once you have determined what you need. Happy to help you figure that out.

A higher end fridge is worth considering, although I think most of these things are close to each other. Definitely worth analyzing the power consumption, adding the cover, and checking the difference.

 

[dstock]

I'd be real interested in the results of all of the above. Keep us posted~!!

I know that I need to replace my main power run, I know that I have a voltage drop, of 0.5v This is lost to resistance in the wiring, it is "consumed" in the wiring, or wasted whatever you want to call it. To eliminate that, or reduce it as much as possible, bigger wiring will help. I doubt you have much if any with what you have, but it is worth a look.

I think what you will find is that at best, you're averaging more than the solar is putting out, at least as you are currently configured, hence the backwards slide.

I would also consider a more serious solar setup, so that you can deploy extra panels once you have determined what you need. Happy to help you figure that out.

A higher end fridge is worth considering, although I think most of these things are close to each other. Definitely worth analyzing the power consumption, adding the cover, and checking the difference.

Thanks, will update as I go forth.

From what I can tell a comparable but smaller Engel still uses 1-2 amps, which is slightly better but in the same ball park as the ARB. I'm thinking more solar will probably be the more cost effective option if I need to add anything.

Granted this was a more extreme scenario, extreme difference in ambient vs fridge temps, parked for 4 days, etc. Even an hour of driving each day this would be a non-issue, but I am trying to learn what I can from this situation to make things as efficient as possible.

 

[LandCruiserPhil]

Have you measured the output of your panel? A Watt's Up Watt Meter & Power Analyzer is an excellent tool to determine your weakness. The meter can tell you both side as for how much accumulative power you are using and producing.

Venting of the fridge area can play a big role on power needs and usages during the summer.

I run a fridge on a 100W panel in AZ

 

[dstock]

Have you measured the output of your panel? A Watt's Up Watt Meter & Power Analyzer is an excellent tool to determine your weakness. The meter can tell you both side as for how much accumulative power you are using and producing.

Venting of the fridge area can play a big role on power needs and usages during the summer.

I run a fridge on a 100W panel in AZ

Thanks for the info, I will check out the meter. For sure I screwed myself on the venting, lessons learned! lol

 

[wrcsixeight]

Making sure the cooling unit can transfer the heat removed from the box is the single best way to increase efficiency. The air intake and exhaust for the cooling unit must not have any restrictions, and keeping the interior of the vehicle at no higher than ambient temps is of utmost importance too. Clean the dust and hair off the condenser can make a huge difference.

Now Odyssey batteries are a fine battery, but when cycled deeply, they require huge recharging currents. They do not make a good "solar only" recharge battery.

If after several cycles they are not fed with a 40% recharge rate, they cannot deliver their rated capacity.

So 100 watts of solar was not enough to keep up with the demands of the fridge, and it certainly is not enough to properly recharge Depleted Odyssey, even if it were not powering a fridge.

Odyssey recommends a minimum 40% current until 14.7 volts are reached( constant current). 14.7v is then to be held for 4 hours while the amps required to hold 14,7 naturally taper( constant voltage). After 4 hours then float at 13.6. If one cannot float at 13.6, better to disconnect the battery than to float it at 13.2v.

So if Your Odyssey batteries have been cycled deeply previous to this outing, and not recharged according to the above regimen, you did not begin this outing with the batteries near their fully charged capacity, even if you drove 20 hours to get there, even if you drove 40 hours. It does not matter how big and shiny and expensive your alternator is either as it is still unlikely to make 40% and then hold 14.7v for 4 hours.

The Odyssey engineer I spoke at length with said such batteries, those deeply cycled, and not recharged according to their recommendations, would require at least 2 cycles down to 50% probably 3, then recharged at the 40% to 14.7 for 4 hours rate before they could reach their maximum energy density.

So there is that.

I don't think upgrading to 8 awg will do much. If you are using a Ciggy plug, even a good one like Blue seas, removing that and installing an anderson power pole or other quality connector will reduce voltage drop more than going from 10awg to 8awg would.

Extra insulation makes a large difference in such temperatures. You can make a 1.5 inch thick foil faced foam panel cooler( with sealed vent holes for compressor and condenser) using bamboo skewers and duct tape to hold it together, which will likely be very effective.

Also Strategies like using a regular cooler for the beers or sodas, and by all means take advantage of evaporative cooling that is possible in dry climates.

I had 104f temps last week and threw out my back. I aimed a fan at a wet sarong, and my IR thermometer said the sarong was 64 degrees. It was like an Ice blanket and I was actually getting the chills, as San Diego burnt down around me.

My Vitrifrigo fridge Never got above 35f inside and I did not increase the setting and my watts up meter said it was using 22 amp hours every 24 hours. I've got an extra 1.5 inches of insulation all around it, and the condenser fan cannot recycle preheated air. It has no choice but to expel it to another area.

 

[theksmith]

you may also be underestimating the impact of adding warm items and opening the fridge when the ambient temperature is high.

my personal experience says that maintaining a consistent temperature consumes many orders of magnitude less energy than reducing the temperature. that might sound intuitive, of course battling a couple degree increase (due to ambient temps) over an hour takes less energy than doing that and reducing an 85* can of Coke to 35*, but combine that concept with that the idea these units seem to operate less efficiently at higher temperatures. perhaps someone here with HVAC training can confirm or dispel that last part.

i usually set my Edgestar 43QT to 35* and then my wireless thermometer will show a swing between 33 and 38. that's plenty cold for most things, and so in the summer i'll even bump it up a couple degrees to use less energy. i fill it the afternoon before a trip and run it on AC power till we leave (extension cord to the Jeep). by the next morning it will have reached the desired temperature and be cycling normally. during summer trips we try to get everything that anyone needs for a while each time the fridge is opened. we also try to keep the fridge in the shade and windows open when possible. if it's not a travel day then i only refill the fridge each morning - if you leave your drinks outside of the vehicle over night then their temperature will be maybe 65* when you add them to the fridge instead of maybe 90* during the day. we always end up traveling at least every other day, so on the days between i just run the Jeep for 20 minutes (don't have solar).

the only time i've ever had the main battery not start the Jeep was the one time in the middle of summer that i didn't use AC power to get everything cold before leaving. i put a bunch of hot sodas in and plugged it into the vehicle. it ran non-stop most of the day trying to just catch up while fighting the 110*+ ambient temp. by the next morning the fridge was still running but there wasn't enough juice to start the Jeep.

 

[UK4X4]

There are good 100w panels and really crap "100w" panels....

a monocrystaline from BP solar for example V's Harbor freight china or a fold up back packing type.

It may say 100watts on the tin but there are huge variances from manufaturer to manufacturer, to the point of some panels don't come out to anywhere near their "rated power"

There are many variables in economically running a fridge under high ambiant temperatures.

battery type and charging is one.
sighting -angle and temperature of the panel
fridge full with pre cooled items, v's half empty
loading the fridge with beer thats at 80oF
quantity of openning time
fridge in the sun ? radiant heat
travel bag or not- adds insulation
good circulation of air arround the motor.

We have an engel 45, with a travel bag, we usually run it as a freezer rather than a fridge, its always full, loaded in the am when stored goods are at their coldest

Usually we turn it off at night, its all still frozen in the morning, we use the fridge basicly full

for cold drinks we run an ice chest, 4 days is easy with a quality one, and you can make ice during the day in the fridge, to suplement.

The fridge runs more efficiently full with as little air as possible.

By turning off at night we 1/2 the consumption

Start the trip with all fridge contents frozen or fully cold
keep the fridge full
open as least as possible
start with a fully charged battery
turn off at night
Insure the panel, wiring and controller does not say made in China anywhere !

 

[geordie4x4]

I am often out in 40 to 45C (104 to 114F) days in summer.

Something that I have also found to be a great help along with one of the insulated travel bags on the fridge is to also add additional insulation particularly on top to keep sun off the fridge.
I have used 6 mm and 10 mm thick foam that has an aluminium foil coating/backing. In Australia the stuff is available from Clarke Rubber but I have no idea what is the equivalent over there.

I have a layer of 6mm foam slid down the insides of the transit bag and a big flat slab of the 10mm foam with foil shiny side up on the top of the fridge lid (just held with velcro tape). I also cut a piece of the foam to fit neatly into each of the back windows and this keeps a huge amount of the radiant heat out of the back of the car. Works well in main windscreen.
Also in the roof lining it stops the heat soaking down through the roof. It has been a bit of an effort to do this but it has been worthwile.

 

[TheDave]

We use a cheap moving blanket from HF to cover our coolers and it makes a huge difference. We just did 5 days (highs of only 80) and we still had over 50% of the ice left. geordie4x4 has the right idea with the foil backed foam.

 

[unseenone]

This product can reduce energy consumption for heating / cooling by as much as 90%. Lining a walk in cooler, camper, house with it really does a good job. It might be a bit much for a car fridge though. http://truprotect.com/