Isotherm Smart Energy Controller (SEC) question

[Jackdaw]

@Maine Sail, (or anyone else),

After quite a bit of research, I'm adding an Isotherm GE 80S Compact Air Cooled Refrigeration Component System with ISEC to keep my built-in icebox on BlueJ cool. Beyond Isotherm's decent reputation and 5 year warranty, I am very attracted to the SEC technology and the power savings, important to me because I plan to run it on my single Group-27 battery (99% racing & day sailing). FYI to all see more about SEC here.

My question is about another feature of the SEC, a smart battery cut-off. Because the system monitors battery voltage, it will not try and run the compressor (to save the battery) if the voltage drops too low. Again, a nice feature on a single battery boat.

But looking at the user manual, I was surprised at the voltage trigger levels. Those seem way too low, basically dead for a resting battery. This only explanation that I can think of is that they are not resting voltages, but under compressor load at the end of the wire. What say you?

 

[dlochner]

Since you are running on a single battery, you might want to consider this unit:
KECO - ATEN S.r.l.
Here's an install on an all electric Pearson 36.
KECO Eco Cooler installation + New Ice Box — Sailing Uma [Step 73] - YouTube

For sailing in your neck of the woods, this would probably be even more efficient than the Sailing Uma folks found.
Just not sure where to buy one in the US.

 

[Jackdaw]

Since you are running on a single battery, you might want to consider this unit:
KECO - ATEN S.r.l.
Here's an install on an all electric Pearson 36.
KECO Eco Cooler installation + New Ice Box — Sailing Uma [Step 73] - YouTube

For sailing in your neck of the woods, this would probably be even more efficient than the Sailing Uma folks found.
Just not sure where to buy one in the US.

Interesting.... I've thought about doing a Peltier Plate install but found them too power hungry under any circumstances. It says that unit:
Current Absorption (with standard mini-pump @ 12,5 V):
- Normal mode (low power): < 2.6 A. or < 1.7 A. (average) if working in Stand-by mode*);
- Burst mode (high power): < 9.5 A. for 5 minutes or less if reached the Stand-by mode*);
- Cycle mode (middle power 20 seconds Burst + 120 seconds Normal): < 5 A o less if in Stand-by mode*).

The SEC-equipped GE80S draws less than 1 amp/hour on average.

 

[sesmith]

Not sure about the low voltage cutout on the unit except to say that that would be measured at the unit with the compressor on , not at the battery (but if your wiring is sized correctly, you shouldn't see much voltage drop between the battery and the unit).

We installed an air cooled cold plate Isotherm unit on our boat last year (Isotherm 3701 asu). It works in a similar fashion to the one you're looking at, except it charges the cold plate at a higher rate when the voltage is higher. It works well and is very efficient, though does cost more than a flat evaporator unit. I did beef up my house bank by replacing the group 24 with 2x EGC2 6 v batteries, and we have solar charging. The voltage protection level on mine is 10v with restart at 12, but we've never run the batteries low enough for that to happen. The unit has been trouble free and we we see it go into high current freeze mode when the sun is out, and when we run the motor. I went with the larger unit rather than the smaller one which was exactly sized for our box, and am glad I did. I also added as much insulation as I could to the box.

 

[Daveinet]

Wonder if the battery voltage choice is really to protect the compressor, rather than protect the battery.

BTY: I've always wondered why no one uses water to cool the condenser. Typically the water is cooler than the air, so that should dramatically increase the efficiency.

 

[dlochner]

BTY: I've always wondered why no one uses water to cool the condenser. Typically the water is cooler than the air, so that should dramatically increase the efficiency.

I do. I have a Grunnert cold plate system that is water cooled. There are 2 large cold plates in the ice box and a water cooled compressor. Once the box is chilled, it seems to be reasonably efficient as the compressor will run twice a day for about 30 minutes. It is a power hog when running drawing ~30 amps. Part of the power draw is the second pump that runs to pump cooling water.

Large cold plates make the system efficient. Smaller plates would warm too quickly requiring the compressor to run more frequently. The cold plates act like big blocks of ice.

Another advantage with water cooling is the heat goes back into the water and not the cabin.

 

[Jackdaw]

Not sure about the low voltage cutout on the unit except to say that that would be measured at the unit with the compressor on , not at the battery (but if your wiring is sized correctly, you shouldn't see much voltage drop between the battery and the unit).

We installed an air cooled cold plate Isotherm unit on our boat last year (Isotherm 3701 asu). It works in a similar fashion to the one you're looking at, except it charges the cold plate at a higher rate when the voltage is higher. It works well and is very efficient, though does cost more than a flat evaporator unit. I did beef up my house bank by replacing the group 24 with 2x EGC2 6 v batteries, and we have solar charging. The voltage protection level on mine is 10v with restart at 12, but we've never run the batteries low enough for that to happen. The unit has been trouble free and we we see it go into high current freeze mode when the sun is out, and when we run the motor. I went with the larger unit rather than the smaller one which was exactly sized for our box, and am glad I did. I also added as much insulation as I could to the box.

Cool. ISEC is basically ASU for evaporator plate systems.. it uses an separate thermometer in the box to how much 'cold' it has stored in liquids in the box, and when they have warmed back up to normal temps.

 

[Maine Sail]

A fridge should not be allowed to take the batteries below about 12.1V. The Blue Sea M-LVD is ideal for this. 10.8V is essentially 0% capacity and should not be relied on as "battery protection"...

 

[Jackdaw]

Wonder if the battery voltage choice is really to protect the compressor, rather than protect the battery.

BTY: I've always wondered why no one uses water to cool the condenser. Typically the water is cooler than the air, so that should dramatically increase the efficiency.

Both evaporator plate and holding plate systems can be either air or water cooled. Water cooling is obviously more complex and requires at least one thru hull. Isotherm has a neat system where the single through hull is a radiator in essence, and doesn't require a separate water pump. Interestingly, the energy efficiency of a water cooled versus air cooled is not different at all. Isotherm rates their air-cooled system to work well up to 115°F, so I think I'll be fine. It's going to be mounted in a huge locker with good ventilation.

 

[dlochner]

Water cooling is obviously more complex and requires at least one thru hull.

Air and water cooled work the same, the difference being the condenser is a tube with a tube. The refrigerant is compressed into a tube with Seawater is pumped through the outer tube and out of the boat, in much the same way that a heat exchanger on an engine works.

An additional through hull may not be necessary. My unit uses the sink drain which is located near the centerline of the boat. There is an outlet on the side of the hull.

 

[Jackdaw]

A fridge should not be allowed to take the batteries below about 12.1V. The Blue Sea M-LVD is ideal for this. 10.8V is essentially 0% capacity and should not be relied on as "battery protection"...

That's what I figured too, and thought that was nonsensical. Thanks for referencing the Blue Sea M-LVD, I haven't seen the product before and that's perfect for my application. Already ordered one

 

[Stu Jackson]

and that's perfect for my application.

Jack, I wonder if it really is. For your application, am I correct in thinking that it is ONLY for daysail use? If that's the case, then perhaps this is a feature that is bells & whistles but meaningless for you if you leave with a full battery and, based on an energy budget, would never take the voltage down that low anyway. A fridge usually uses 60 ah in a 24 hour period (some newer fridges use less, but perhaps not remarkably less). So, with a full battery you already have maybe 50 ah AVAILABLE to you for a simple daysail, and you'd need 30 ah - half a day - for the fridge, so you have 20 ah available for your other energy needs (i.e., instruments, etc.). If you're going overnight, then your single battery is utterly undersized, right?

Wonder if the battery voltage choice is really to protect the compressor, rather than protect the battery.

That's my read on it, too. It "can't" protect the battery, because the battery voltage will drop if you use too much of it anyway. It simply stops the compressor from trying to start on low voltage.

Maine Sail's point is that recharging should start when battery voltage reaches 12.1V. He's mentioned this hundreds of times in his recurring posts on battery management.

 

[Jackdaw]

Jack, I wonder if it really is. For your application, am I correct in thinking that it is ONLY for daysail use? If that's the case, then perhaps this is a feature that is bells & whistles but meaningless for you if you leave with a full battery and, based on an energy budget, would never take the voltage down that low anyway. A fridge usually uses 60 ah in a 24 hour period (some newer fridges use less, but perhaps not remarkably less). So, with a full battery you already have maybe 50 ah AVAILABLE to you for a simple daysail, and you'd need 30 ah - half a day - for the fridge, so you have 20 ah available for your other energy needs (i.e., instruments, etc.). If you're going overnight, then your single battery is utterly undersized, right?

That's my read on it, too. It "can't" protect the battery, because the battery voltage will drop if you use too much of it anyway. It simply stops the compressor from trying to start on low voltage.

Maine Sail's point is that recharging should start when battery voltage reaches 12.1V. He's mentioned this hundreds of times in his recurring posts on battery management.

Stu, I see the point you're making. I'll explain my application better.

I'm not worried at all about it running out during the course of a day sail, or even for a night out on the hook. I'm much more worried about it back at the dock. At WYC we have sort of an ad-hoc shore power system. Weather protected household outlets on every fifth or sixth slip. By design one is in front of my boat, and I plug-in most nights. And most people know it's mine. But it's always possible that someone could unplug it to use a power washer and forget the plug me back in, or it could trip. I could come back to the boat after several days for a race, and find the battery dead and unable to start. Maybe plugging back in the shore power would get it to start after a while, but that certainly wouldn't be good for the battery!

 

[Stu Jackson]

Jack, then a small solar panel should be on you Xmas list. Really. Before we moved to Canada last summer, and left the boat in SF, I bought an inexpensive solar controller and hooked my ancient 11w solar panel to it. When we returned to the boat a month later, the batteries we just fine. Of course, other than the bilge pump, no loads were left on.

It is unclear to me from your post whether or not you plan to run the fridge when you're away from the boat and plugged in. Can you fill in the blanks?

 

[walt]

And most people know it's mine

If its "yours" (ie, you are paying for it), why not just put a lock on the plug so that it can not be removed?

If its one of those deals where the plug was intended to be shared by a bunch of slips.. I can see your problem..

 

[Jackdaw]

Jack, then a small solar panel should be on you Xmas list. Really. Before we moved to Canada last summer, and left the boat in SF, I bought an inexpensive solar controller and hooked my ancient 11w solar panel to it. When we returned to the boat a month later, the batteries we just fine. Of course, other than the bilge pump, no loads were left on.

It is unclear to me from your post whether or not you plan to run the fridge when you're away from the boat and plugged in. Can you fill in the blanks?

For SURE leave it on all the time. The plan is to always have cold beer! ;^)

Often we come to the boat for a race and its 90F. If the box was not on, then it would take several hours to cool off. So we'll leave it on with beer it it all the time. We're at the boat 3-4 times a week, so its worth it.

 

[Jackdaw]

If its "yours" (ie, you are paying for it), why not just put a lock on the plug so that it can not be removed?

If its one of those deals where the plug was intended to be shared by a bunch of slips.. I can see your problem..

'Mine' means its in front of my boat, and via 'first-come-first-served' rule I claim it! But the good new is that 95% of the boats at WYC do NOT have shore power, so nobody really cares, as long as they can use it for simple one-off tasks like power washing or power tools.

The trick is that I need to get plugged back in.

 

[Stu Jackson]

The trick is that I need to get plugged back in.

ITWMB, I'd get a solar panel and a small controller right away. Since you're at the boat regularly, what you want to do (absent getting more batteries because of weight, right?), would be to EXTEND the time the fridge could run if some bozo unplugged you. If the fridge setting is on low when you leave (to reduce the electrical load overnight and when you're absent), it will keep beer cool without overtaxing the electrical system you have. A properly sized solar panel could get you through a day of being unplugged if you can't make it to the boat. If you're interested in this idea,we can run some #s for you.

 

[Daveinet]

Run the fridge off shore power directly from a converter. Leave the battery out of the question. If someone forgets to plug you back in, your fridge is warm, but your battery is still good.

 

[Jackdaw]

Run the fridge off shore power directly from a converter. Leave the battery out of the question. If someone forgets to plug you back in, your fridge is warm, but your battery is still good.

There are some units (Norcold) that are shipped as AC/DC units and automatically switch. They (norcold) have bad reputations however. Isotherm does make a wired AC adapter. but it is not compatible with ISEC. After thinking about it. I'll take the advantages of ISEC while sailing and deal with the power interruption onshore in another way. The BSS low-battery trip seems the best solution. I have to buy one $70 part, install and forget about it. Now my beer stays cold 99.5% of the time, and I don't have to change any part of my routine.