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Old 27-04-2015, 20:17   #16
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Re: 12v Fridge power use

This question always invokes lots of different answers. First, fault find your own system. Make certain that it gets the volts it needs with no bad connections, and correctly sized cables. If it is air cooled, make sure it can get sufficient air. Make sure the seals for the doors are good, and the insulation is dry and in good condition. Make sure there are NO HOLES in the insulation. A good, sealed, well insulated cabinet is the easiest for any system to cool, and to keep cool!
Here are a couple of links about cabinets to help minimise power use;
Refrigeration Cabinets, Power Consumption Boating Gear fit for the King
And
Ozefridge Marine Refrigeration Boating Gear fit for the King
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Old 27-04-2015, 20:26   #17
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Re: 12v Fridge power use

I have an 15-20 yr old AB unit. With 450 amp/hr battery bank I can stay charged with a 130 watt panel running frig 24/7. I don't run computer much. Quit using computer for a day and see if it changes. Are you getting much shading on your panels and how old are the batteries? Tim
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Old 27-04-2015, 23:44   #18
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Re: 12v Fridge power use

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Originally Posted by captainwireman View Post
What are the most efficient refrig/freezers on the market? How much foam in inches would you recommend. My unit needs replacing and my box needs a remodel. I have a top load with the existing unit in a space alongside. Would a low amp draw fan that would run with the compressor unit make sense?
How much insulation would I recommed?
4" for a refrigerator and 5" for a freezer.

What type or foam?
I like the polyisocyanutate sold under the RMax label at home depot for about $20 for a 4ft x 8ft sheet 1" thick. It is foil lined as a good vapor barrier and you use foil tape to seal any cut edges. Stack it all together with 3M 77 contact adhesive spray and then add a good ABS or fiberglass sheet board over the top and Boom...a great box for cruiser cheap that will last for years.

Does adding in a low amp draw fan help?
That depends on the type of unit you have and the ambient temp where the compressor is mounted. All systems (except for keel cooled) have a 12v fan blowing or pushing air through the condensing coils, so that is standard. Some units start to lose efficiency at 90degs F, while others can go up to 120degs before they lose efficiency. That's all a factor in condensor design and surface area.

Who makes the most efficient system?
I'll pass on that question because if I gave my opinion it would be a little self serving since I'm the owner of Technautics and fund my cruising/live aboard kitty by selling these things.
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Old 28-04-2015, 06:15   #19
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Thumbs up Re: 12v Fridge power use

I checked all the wires and the voltage is good. I don't use the fridge or shore power ever so taking out the voltage sensor might save some power but I have to look into how that is done.
However it is hot here and I have to admit I open the front loading fridge too often. It is also not full so maybe stacking in some cokes will help for all those times I open and close the door. Regardless it does seem like I am using more than I am putting in from my batteries. I do have a honda 2000 and use it on cloudy days. I have a nice 60A charger that tops up my bank really quickly. This morning I woke up to 12.1 volts so definately time to break out the generator today.
I turned the temp down to 5 which may also help significant.
Excellent help all. Thank you so much!

ST
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Old 28-04-2015, 06:23   #20
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Re: 12v Fridge power use

Quote:
Originally Posted by Scubatony View Post
I checked all the wires and the voltage is good. I don't use the fridge or shore power ever so taking out the voltage sensor might save some power but I have to look into how that is done.
However it is hot here and I have to admit I open the front loading fridge too often. It is also not full so maybe stacking in some cokes will help for all those times I open and close the door. Regardless it does seem like I am using more than I am putting in from my batteries. I do have a honda 2000 and use it on cloudy days. I have a nice 60A charger that tops up my bank really quickly. This morning I woke up to 12.1 volts so definately time to break out the generator today.
I turned the temp down to 5 which may also help significant.
Excellent help all. Thank you so much!

ST
You could consider adding battery capacity.

Limiting how often you open the door and how long you leave it open will help. The cold air falls out when the door is opened.
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Old 28-04-2015, 06:26   #21
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Re: 12v Fridge power use

Isotherm Cruise CR 130 Classic Refrigerator / Freezer with ASU
Model No. 1130EE1AA0000C
Current Draw:
Compressor Running: 4.7 - 5.0 Amp @ 12 Volt DC (half at 24 Volt DC)
Average: 1.2 Amp @ 12 Volt DC
Average draw measured at 43F in refrigerator, 72F ambient temperature
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Old 28-04-2015, 06:38   #22
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Re: 12v Fridge power use

Quote:
Originally Posted by Scubatony View Post
I checked all the wires and the voltage is good. I don't use the fridge or shore power ever so taking out the voltage sensor might save some power but I have to look into how that is done.
However it is hot here and I have to admit I open the front loading fridge too often. It is also not full so maybe stacking in some cokes will help for all those times I open and close the door. Regardless it does seem like I am using more than I am putting in from my batteries. I do have a honda 2000 and use it on cloudy days. I have a nice 60A charger that tops up my bank really quickly. This morning I woke up to 12.1 volts so definately time to break out the generator today.
I turned the temp down to 5 which may also help significant.
Excellent help all. Thank you so much!

ST
Hi Tony,

One question. Under what conditions are you measuring the battery voltage in the morning? If the fridge compressor, lights or some other loads are running it will draw down the battery voltage.

Perhaps you already know that the voltage should be checked with no loads on to get a better idea of the state of charge.
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Old 28-04-2015, 09:21   #23
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Re: 12v Fridge power use

Quote:
Originally Posted by Scubatony View Post
Thanks for all the comments. I have the cruise 130 isotherm. The manual is telling me .6-2.5 amps. X 24 hours that 2.5 really adds up.
It has fair ventilation to the compressor but it could be better. More insulation sounds good but I can't see where I would use it as my installation is already tight.
Good to know it is likely just a power hungry device rather than another issue of my system.

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Size your system for the high end. You'll be surprised how much power your refrig / freezer uses. How are you measuring your daily consumption?

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Old 28-04-2015, 12:59   #24
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Re: 12v Fridge power use

get a battery monitor....
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Old 29-04-2015, 09:44   #25
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Re: 12v Fridge power use

I don't have a perfect way to measure usage. Thus my problem with how much the fridge sucks. A battery monitor would be great or even an inline amp meter would help.
I check the voltage each morning with everything off. Yesterday I topped off in the morning with one hour run of my eu2000. By noon I was in trickle mode on the solar and at dusk with all loads off I had 12.7 V. Today it is windy and sunny. About 6 amps from my wind and 9 from my solar should be good for today as well.
I guess my system is not that bad. I only use my gen about every 10 days depending on conditions. Solar is by far my best mode but two days of clouds and I'm firing up the genie again.
Thanks again for all the help here.


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Old 29-04-2015, 10:32   #26
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Re: 12v Fridge power use

If your solar is on trickle at 12.7 volts on battery there is something not right ours doesn't enter float until the bank is about 13 v on the fluke clamp on
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Old 29-04-2015, 11:07   #27
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Re: 12v Fridge power use

Quote:
Originally Posted by Scubatony View Post
I don't have a perfect way to measure usage. Thus my problem with how much the fridge sucks. A battery monitor would be great or even an inline amp meter would help.
Record of Daily Energy Use of 100 ah per day:

"Breaking In" New Wet Cell Batteries
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Old 29-04-2015, 12:18   #28
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Re: 12v Fridge power use

If you want to know exactly how much electricity a component uses in a day, you can use one of these things.
Digital DC Ammeter, Amp Hour Meter, Watt Hour Meter
I use it on my dive scooter which has a kilowatt / hour LIPO battery and it can draw I believe about 1,000 watts on high power. I'm saying this as the watts up meter can easily pass though and measure more power than any single item on a boat ought to be able to use.
Dead simple to wire in, run the item for a few days reading how many amps or watts you use and you know, then move it to another component.

I think about 5 amps draw for a fridge is about average, and that isn't but 65 watts, assuming 13 volts, that really isn't that much
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Old 29-04-2015, 13:08   #29
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Re: 12v Fridge power use

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Originally Posted by Scubatony View Post
I have a new Isotherm refrigerator for my small boat. It runs 24/7 and I am in the bahamas. The list power consumption is supposed to be very good. I think .6 -1 amp per hour. That would put my use at around 24 amps per day. I have 250 watts of solar plus a wind gen charging into a 270 amp bank of flooded cells which are also new. A typical day of charging gets me 60-70 ah of total charge plus maybe another 12-24 ah from the wind gen.
The issue is I never seem to get caught up to trickle my batts. My voltage will sometimes get to 12.2V by morning. Not bad but lower than I would like. I am very conservative with other usage. LED lights, I rarely turn on my fan and dont have AC or Radar. MY water pumps kicks on for seconds at a time a few times a day. I guess my laptop would be the #2 consumer.
So my question is in the heat here what is the actual consumption of the fridge? Would it be closer to 50-60 ah per day? If that is the case I am probably pretty close to my total usage and am just breaking even every day.

Bazinga
I have the same size house bank as you, and the Isotherm 2501. We have lived aboard and cruised for the past 2 1/2 years. Just figure 2.5 amps per hour (60 amps) for the fridge. I experience about the same voltage in the mornings, during summer months or when in the Bahamas. The temperature, and water temp has much to do with it. I'd say you are spot on. I hate to, but probably going to 4 T-105's (Golf Cart batteries) before we head back to the Bahamas. We only have 100 watts of solar, but adding another 100 watts. I also have an old wind generator, but it puts in very little unless the wind is really cranking. I have the Xantrex LinkLite battery monitor, so it's easy to see what's going on.

Good luck!
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Old 30-04-2015, 20:46   #30
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Re: 12v Fridge power use

I have a Vitrifrigo c51is.

I added more insulation to the box, and insulated the cabinet in which it resides.

This extra insulation allowed me to move the 120MM fan to the other side of the condenser so that it pushes air across the condenser, then compressor and compressor controller. I made a cover over the cooling unit portion so that cool filtered air is sucked from below the fridge, through the condenser and out the cooling unit tunnel and this heated air has no chance of being recycled. It is pushed out of the cabinet after one pass by the same fan.

I also used a new Quiet Noctua Nf-f12 fan which is ~53 CFM and 0.05 amps to replace the Vitrifrigo provided Noisy ~72 cfm fan that drew 0.13amps.

I do have another 0.05a 80MM fan in the adjacent cabinet running 24/7 that causes a steady slight flow of air through fridge airpath.

I also added a 0.03a 40MM ~6 cfm fan to the interior, taking power from the light. it too runs 24/7 and blows into the freezer compartment. With the fan a setting of 2.2 of 7 keeps the entire interior under 34F. Without the fan I need a setting of 4 of 7 to get all locations under 36.5 F, and some of them will be 27F.

I Own a GTpower inline watt meter, very similar to the 'watts up' meter. I replaced the aluminum 12awg wire with tinned 8 awg right to the circuit board and use 45 amp anderson powerpoles.

When I hook this inline on my fridge, It took over 5 days before It measured 60 amp hours in an average ambient temp of 70F, and normal use, opening multiple times daily and adding foodstuffs, and beer. The GTpower meter cannot read loads under 0.05a, so I add 1AH consumption to the reading for every 24 hours to account for the other fans I run for the fridge.



Best way to increase efficiency of these fridges is to make sure the compressor and condenser are not bathed in hot air that they themselves have heated.

The Danfoss BD35f can power upto 0.5a of 12v fans. One can add another fan to exhaust the cabinet where the cooling unit resides. it will only run when the compressor fires up.

It could power 10 Noctua NF-f12 fans if it had to. Don't just use any computer fan, they vary greatly in air moved for current consumed and Noise made. They all do better when pushing air through a condenser, rather than pulling it through, and are quieter doing so.

Let that cooling unit breathe and your batteries will thank you.

Also you state that you have a 60 amp charger which 'tops off the batteries quickly' If these are Lead acid batteries, you are not getting from 80% to 100% State of charge in under 2 hours no matter how much confidence you have in your charger or its marketing. 4 hours is more reasonable to reach a true 100% charge from 80% and that is with a higher absorption voltage than most chargers do.

So it is likely your batteries are now capacity compromised from chronic undercharging due to the misbelief that lead acid batteries can be quickly returned to full charge.

Here is my cooling unit tunnel:


The tunnel also serves to protect the cooling unit on insertion and removal as it is a super tight fit in my cabinet:


This fans location makes it much easier to clean the fan blades and condenser fins too as dust build up is an issue:



I added an air filter to the intake to keep the dust build up to a minimum. The filter turns black all too quickly.

There is certainly good airflow when the compressor kicks on:

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