New fridge efficiency!

[Jackdaw]

I installed an Isotherm GE 80s ISEC refrigeration system in my existing icebox. I'm very pleased. First pleased that the existing insulation in the box is thick for a 25 footer. Isotherm recommends 3-5cm of insulation for fridges <80L. Ours is 50L and looks like it splits the diff with 4cm.

Next the install went very smoothly, and the plate fit like a glove.

But the biggest news is the efficiency. The boat has a single Group 29 battery rated at 85 amp/hour capacity. Yesterday as a test I unplugged the boat from shore power at 7AM. It was in the 80s to 90 all day. Fridge is set at 42F. Twelve hours later I came back and checked the resting battery voltage.

That's 90% of full charge, meaning that the fridge used 8.5 amps in those 12 hours, or a 0.7A/hour run rate. Very good, and matches specs and other users observations. That's less than an incandescent anchor light!

 

[Justin_NSA]

Cool ! No pun intended. We bought Bella knowing the the fridge wasn't working. Been using it as an icebox. I wonder it it would be smarter to replace just the old defective compressor or go with a whole new system like this.
Is it something you can do yourself and save labor $$ ?

 

[Jackdaw]

Cool ! No pun intended. We bought Bella knowing the the fridge wasn't working. Been using it as an icebox. I wonder it it would be smarter to replace just the old defective compressor or go with a whole new system like this.
Is it something you can do yourself and save labor $$ ?

I did the install myself, solo. It took 3 hours. It was rather straightforward... just a lot of steps.

 

[Justin_NSA]

I did the install myself, solo. It took 3 hours. It was rather straightforward... just a lot of steps.

No special equipment for gas charging or anything?

 

[Jackdaw]

No special equipment for gas charging or anything?

No, it comes pre-charged, and the quick-connect connectors can be closed and opened without losing the refrigerant.

 

[Justin_NSA]

Sweet !

 

[kloudie1]

nice install !

 

[Gunni]

Shame to see you waste that cool on industrial beer!

 

[Jackdaw]

Shame to see you waste that cool on industrial beer!

We usually have some decent Surly or Bells in there. MGD is Jodi's favorite beer. And if it keeps her happy and looking the way she does, we'll stock it! ^)

 

[markwbird]

I did a similar project on my H-34. It also has a very well insulated ice box. I installed an Isotherm unit as well. The combination of thick insulation, moderate temperature in the bay area and 55 degree water under the boat means that I have to keep the unit setting almost all the way down or I have a freezer. Very pleased with it.

 

[Jackdaw]

I did a similar project on my H-34. It also has a very well insulated ice box. I installed an Isotherm unit as well. The combination of thick insulation, moderate temperature in the bay area and 55 degree water under the boat means that I have to keep the unit setting almost all the way down or I have a freezer. Very pleased with it.

You should think about adding the ISEC controller to your fridge. It improves power consumption between 30-50%.

Its about $150 and an easy install.

 

[agprice22]

Do you leave your fridge on during the week when you are not at the boat? I have wondered about leaving the fridge running when the boat is on shore power just to keep some drinks cold. It seems a waste when I can bring them cold in a cooler.
We enjoyed our electric cooler last season, but I have considered adding a fridge. We weekend on the boat, but since it is over an hour away, we rarely get up there for more than the weekend.

 

[jfgy]

Very cool indeed, Jackdaw. Could you please tell me where you installed it and how is it ventilated? Where does the hot exhaust air exit?
Many thanks.
Jess
(Hunter 27, Jacksonville, FL)

 

[JRacer]

It wouldn't have to work as hard if it was FULL of Beer! ;-)

 

[Jackdaw]

Do you leave your fridge on during the week when you are not at the boat? I have wondered about leaving the fridge running when the boat is on shore power just to keep some drinks cold. It seems a waste when I can bring them cold in a cooler.
We enjoyed our electric cooler last season, but I have considered adding a fridge. We weekend on the boat, but since it is over an hour away, we rarely get up there for more than the weekend.

When we started, we would bring a bunch of cold beer and a bag of ice to the boat before a race and dump them in the icebox. The problem was the boat (and the icebox) was 80+F degrees, and in the 2 hours we raced the ice melted cooling the box down to 60. Warm beer. So we stopped that, and brought beer and ice in a soft cooler.

So yes we leave it running all the time, just like at home. We're at the boat 3-5 times a week, so not much sense in turning it on and off all the time. Plus the the ISEC system uses shore-powered time to sink cold into beverages in the box, and then uses much less battery for the rest of that day.

 

[agprice22]

So yes we leave it running all the time, just like at home. We're at the boat 3-5 times a week, so not much sense in turning it on and off all the time. Plus the the ISEC system uses shore-powered time to sink cold into beverages in the box, and then uses much less battery for the rest of that day.

Thanks. I keep hemming on doing this for my boat because I feel bad leaving it on just to keep beer cold. However, my electric cooler requires a day lead time to get really cold. Then you can only add cold food. I am probably using way more electricity doing that than you are. I am going to look at the unit you quoted.

 

[SirMichael]

I have a suggestion. Rather than guesstimating the efficiency of the DC unit from the DC voltage on your battery, why not put in a DC Current meter so that you can monitor your battery usage by the current draw? I put a voltage and current meter in my boat last year and mounted just below the DC switch panel. Anytime the DC is turned on, the meter is on as well, and it shows how much current is being used on the boat. Even seems to be reasonably accurate below 1 amp.

Do a search for "LED Digital Volt meter Ammeter" on Amazon to get an idea of what meters are available. (Yeah, I know, things on a boat are SUPPOSED to be very costly!) The meter measures the voltage drop across the "shunt". The shunt may have about 0.050 to 0.075 volts across it. That small of a voltage drop won't affect your lights or refrigerator at all.

To install, you put the shunt (large metal bar) in the ground return lead back to the battery from the DC panel. You also connect up to the 12v line to power the meter (it uses VERY little current). Mount the meter either in the DC panel or somewhere in the area.

The current meter makes it easier to keep track of the load you are putting on your batteries so you know how much current each device requires. Incidentally, the meter won't show your engine Starter current, only the current that goes through your DC panel system.

Mike

 

[Jackdaw]

I have a suggestion. Rather than guesstimating the efficiency of the DC unit from the DC voltage on your battery, why not put in a DC Current meter so that you can monitor your battery usage by the current draw? I put a voltage and current meter in my boat last year and mounted just below the DC switch panel. Anytime the DC is turned on, the meter is on as well, and it shows how much current is being used on the boat. Even seems to be reasonably accurate below 1 amp.

Do a search for "LED Digital Volt meter Ammeter" on Amazon to get an idea of what meters are available. (Yeah, I know, things on a boat are SUPPOSED to be very costly!) The meter measures the voltage drop across the "shunt". The shunt may have about 0.050 to 0.075 volts across it. That small of a voltage drop won't affect your lights or refrigerator at all.

To install, you put the shunt (large metal bar) in the ground return lead back to the battery from the DC panel. You also connect up to the 12v line to power the meter (it uses VERY little current). Mount the meter either in the DC panel or somewhere in the area.

The current meter makes it easier to keep track of the load you are putting on your batteries so you know how much current each device requires. Incidentally, the meter won't show your engine Starter current, only the current that goes through your DC panel system.

Mike

I've thought about that, and indeed on all my other boat I have installed a shunt-based NASA Clipper BM-2 battery monitor. But on BlueJ the power loads and excursions are more modest for now, so this works.

And speaking of working, I'm not seeing what you are talking about when you say guesstimating. When trying to know how much water has drained out of a bucket, you can measure the flow in real time, or measure whats left and subtract that from how much was in the full bucket. Thats what I did, resting voltage is an accepted way to know percentage of charge remaining. No system measures perfectly or gives exact results, but this is way close enough for me; I just wanted to validate the numbers I was told to expect.

 

[Benny17441]

Jackdaw, 12.67V is the voltage of a fully charged battery at rest. I'm not questioning the efficiency of the fridge but don't think that little plug voltage gauge is giving a correct reading. Run the test again and let the battery rest for 2 hours and use a digital multimeter getting a reading at the battery terminals. The thickness of that insulation is impressive and it seems those units are real efficient but for your own peace of mind check out the actual power consumption. Yes, running them 24/7 on shore power is the way to go, I don't think they are going to wear out any sooner and the beer will always be cold.

 

[Jackdaw]

Jackdaw, 12.67V is the voltage of a fully charged battery at rest. I'm not questioning the efficiency of the fridge but don't think that little plug voltage gauge is giving a correct reading. Run the test again and let the battery rest for 2 hours and use a digital multimeter getting a reading at the battery terminals. The thickness of that insulation is impressive and it seems those units are real efficient but for your own peace of mind check out the actual power consumption. Yes, running them 24/7 on shore power is the way to go, I don't think they are going to wear out any sooner and the beer will always be cold.

I know that this little thing is probably not worth having 2 significant digits past the decimal! ;^)

However, all wet cell DC battery charge charts look something like this.