New Isotherm energy use testing results

[GeorgeRa]

I butchered the screw in order to take it out. Replacing almost impossible, it was 3.5mm x 9mm screw, but rethreading to #6-32 worked OK. My compressor bottom plate is mounted on 4 posts with clips, remounting should be easy.

[GeorgeRa]

My new controller is in, it seems as design is the combination afterthoughts. I have never seen a design where turning a regular screw in counterclockwise direction to tighten the assembly. See the screw highlighted in red. Must be the Lamborghini way.

[tgregg]

Booster,

What did you have your battery protect set at when testing the ITC?

The reason I ask is we have the ITC installed and after a recent week trip to florida we seem to find it acceptable. Our biggest reasons for installing were the non mechanical thermostat, the soft start, the temperature display and the digital control of the set temperature.

I was always wakened during the night by the mechanical thermostat and the sudden compressor noise. Admittedly I'm a light sleeper.

The lack of precise repeatable set point (our knob had no numbers) and the need to open the refrigerator to check a manual thermometer caused a lot of too cold, too hot 'discussions' between the chef and the equipment manager.

I think the behavior of ITC mode is controlled by the battery protect level set.

I agree that in ECO mode the compressor rpm is always 2500 but in ITC mode it's either 2500, 2500-3500 or 3500 depending on which range the battery voltage falls in.

Ours is set to the highest level, level 3 because we have LiFePo batteries and it only runs at 3500 if we are charging with the alternator when driving or if the batteries have been recently charged. Otherwise it runs between 2500-3500. I suppose it would run at 2500 if the voltage fell below the lowest voltage in level 3 if the inverter was on at the same time.

We generally run in ITC when driving and switch to ECO mode if we're going to stay put for several days.

We don't notice the temperature swings you experience, but my test is far from scientific. The display is mounted inside a kitchen cabinet (so we aren't bothered by the light at night) that used quite often during breakfast, lunch snd dinner and every time we open the cabinet the display shows 42 our set point or very infrequently 44.

Because the sensor is reading the air and not the temperature of the food, I suspect the food temperature is fairly stable.

It's difficult to isolate the energy used because of other devices that may be on. We have an hour meter and use it to indicate any fall off in performance. It's usually less than 6 hours in a 24 period. We tend not to camp where it's hot.

And yes, we have the refrigerator on a separate circuit breaker so we can shut it off when not using it to eliminate any parasitic battery drain.

After reading your posts and our recent trip, I thought I would mention my conclusions about the importance of selecting the correct battery protect level if you're going to use ITC mode.

Tom

[booster]

Originally Posted by tgregg

Booster,

What did you have your battery protect set at when testing the ITC?

The reason I ask is we have the ITC installed and after a recent week trip to florida we seem to find it acceptable. Our biggest reasons for installing were the non mechanical thermostat, the soft start, the temperature display and the digital control of the set temperature.

I was always wakened during the night by the mechanical thermostat and the sudden compressor noise. Admittedly I'm a light sleeper.

The lack of precise repeatable set point (our knob had no numbers) and the need to open the refrigerator to check a manual thermometer caused a lot of too cold, too hot 'discussions' between the chef and the equipment manager.

I think the behavior of ITC mode is controlled by the battery protect level set.

I agree that in ECO mode the compressor rpm is always 2500 but in ITC mode it's either 2500, 2500-3500 or 3500 depending on which range the battery voltage falls in.

Ours is set to the highest level, level 3 because we have LiFePo batteries and it only runs at 3500 if we are charging with the alternator when driving or if the batteries have been recently charged. Otherwise it runs between 2500-3500. I suppose it would run at 2500 if the voltage fell below the lowest voltage in level 3 if the inverter was on at the same time.

We generally run in ITC when driving and switch to ECO mode if we're going to stay put for several days.

We don't notice the temperature swings you experience, but my test is far from scientific. The display is mounted inside a kitchen cabinet (so we aren't bothered by the light at night) that used quite often during breakfast, lunch snd dinner and every time we open the cabinet the display shows 42 our set point or very infrequently 44.

Because the sensor is reading the air and not the temperature of the food, I suspect the food temperature is fairly stable.

It's difficult to isolate the energy used because of other devices that may be on. We have an hour meter and use it to indicate any fall off in performance. It's usually less than 6 hours in a 24 period. We tend not to camp where it's hot.

And yes, we have the refrigerator on a separate circuit breaker so we can shut it off when not using it to eliminate any parasitic battery drain.

After reading your posts and our recent trip, I thought I would mention my conclusions about the importance of selecting the correct battery protect level if you're going to use ITC mode.

Tom

The instructions for the ITC show the battery protection speeds at the various input voltages for each of the battery protector settings IIRC. I don't have the book anymore as I threw it out along with the ITC.


Think yours is acting like it designed to so if you are in ITC mode it should vary speed, but there is no way to check speed except by looking at power usage, which is what I did in checking ours. The speed should not just be varied by the input voltage, though, I am pretty sure. When it is ITC mode it should go to the highest speed for the voltage in the chart but also should slow down if it is keeping up easily, to save energy. Ideally, it appears the unit is designed more for lead acid batteries and should only lock into the the highest speed all the time to store cold in the frig contents when it is seeing charging level voltage of probably about 13.2v or higher, but I think that is set with the battery saver setting. Your lithium is probably keeping you near top speed all the time. I tested ours both on charge voltage (float) of 13.2v and on batteries from 12.9 to 12.5v and always got the same energy use under controlled conditions. As mentioned in the discussion, it used a lot more energy in ITC mode than ECO mode, but both used a bunch more than the mechanical thermostat with speed control set at 2000 rpm. With the multipoint speed control, now do know what are compressor speeds are pretty closely, but not exactly because I have more speeds than list in Secop speed vs resistance chart so I have to interpolate between their listed points. It is not linear with resistance so not right on that way.

I just looked at the online version of the manual and here is the chart you refer to.



https://www.classbforum.com/forums/a...1&d=1646704884


From the chart, in level 3 you would have to get down to 13.7v to get off of high speed and onto variable speeds which would slow down continuously with cooling load I think (probably based on run time or off time). Very possible you might never get there or even if you do have a very low reduction in speed.


I am surprised you aren't seeing the big temp swings we did, but you are running very high frig temps compared to anything we would even consider. We like to run in the 36-28 degree range. Most "experts" in the food safety fields would put the highest limit at 41* from what I have seen, but that high some stuff just doesn't last very well in the frig for us. The older electronic controls from Isotherm sometimes had a fixed setpoint, I am pretty sure. The very first one did similar to the ITC in overcooling when at charging temps, but had no adjustments for setting so always at 41*, which many users didn't like. You will run very efficient at your settings though. Isotherm told me that the temp swings should be 2-4*F, but ours always had more than that. Of course swings can be off by a degree on each end because of the 2 degree readout steps with no 1/10 degree digit.


We measure the input conditions and power use with a Wattsup tiny battery monitor that accumulates energy use over time. It is nice that it gives both AH and whr totals so you can use the Whr reading which is comparable at different voltages. You do have to wire it in the pos and neg wires to the frig, though, but ours is on plugs for easy disconnect of the frig so I just put mating plugs on the Wattsup so I can take it in and out easily. We have it on a plain old on/off rocker switch that lives by the speed control as I am not a fan of using non switch rated breakers as on/off switches. We use no power when off and only a few milliamps when it is on but not running. The ITC took much, much more power than that all the time as stated in the discussion.


You are aware, I hope, that if you ITC dies you cannot just put the mechanical thermostat back online to get the frig running. You have to put in another ITC or replace the compressor control module to go back to the mechanical thermostat, which I had to do on ours.

[GeorgeRa]

Originally Posted by tgregg

Booster,

What did you have your battery protect set at when testing the ITC?

The reason I ask is we have the ITC installed and after a recent week trip to florida we seem to find it acceptable. Our biggest reasons for installing were the non mechanical thermostat, the soft start, the temperature display and the digital control of the set temperature.

I was always wakened during the night by the mechanical thermostat and the sudden compressor noise. Admittedly I'm a light sleeper.

The lack of precise repeatable set point (our knob had no numbers) and the need to open the refrigerator to check a manual thermometer caused a lot of too cold, too hot 'discussions' between the chef and the equipment manager.

I think the behavior of ITC mode is controlled by the battery protect level set.

I agree that in ECO mode the compressor rpm is always 2500 but in ITC mode it's either 2500, 2500-3500 or 3500 depending on which range the battery voltage falls in.

Ours is set to the highest level, level 3 because we have LiFePo batteries and it only runs at 3500 if we are charging with the alternator when driving or if the batteries have been recently charged. Otherwise it runs between 2500-3500. I suppose it would run at 2500 if the voltage fell below the lowest voltage in level 3 if the inverter was on at the same time.

We generally run in ITC when driving and switch to ECO mode if we're going to stay put for several days.

We don't notice the temperature swings you experience, but my test is far from scientific. The display is mounted inside a kitchen cabinet (so we aren't bothered by the light at night) that used quite often during breakfast, lunch snd dinner and every time we open the cabinet the display shows 42 our set point or very infrequently 44.

Because the sensor is reading the air and not the temperature of the food, I suspect the food temperature is fairly stable.

It's difficult to isolate the energy used because of other devices that may be on. We have an hour meter and use it to indicate any fall off in performance. It's usually less than 6 hours in a 24 period. We tend not to camp where it's hot.

And yes, we have the refrigerator on a separate circuit breaker so we can shut it off when not using it to eliminate any parasitic battery drain.

After reading your posts and our recent trip, I thought I would mention my conclusions about the importance of selecting the correct battery protect level if you're going to use ITC mode.

Tom

Hi Tom, I am leaning towards ITC as well primarily due to mechanical switching noise of the capillary thermostat and difficulties with replacing capillary.

Did you add a switch for the fridge lamp when ITC is turned off to keep the door partially open?

[tgregg]

This is the chart I was referring to:

The paper manual shows the last row as V > 13.8.

I would guess the speed used in the third row would be based on battery voltage.

Are you saying if the battery voltage was in the third row it would use 3500 and slow down to 2500 if it could maintain the set point?

That sounds like a Danfoss feature I read about years ago where the compressor would start with a different speed each cycle until it found a speed it could maintain the set point while running for an optimum duty cycle. I didn't think any refrigerator used that feature anymore.

[tgregg]

Originally Posted by GeorgeRa

Hi Tom, I am leaning towards ITC as well primarily due to mechanical switching noise of the capillary thermostat and difficulties with replacing capillary.

Did you add a switch for the fridge lamp when ITC is turned off to keep the door partially open?

I don't have a light, but I do have a marine circuit breaker that is switch rated that I use to turn the whole unit off when not in use.

My refrigerator is sold by Dometic, but it's also sold by Isotherm and it uses a secop - danfoss bd35 compressor so the ITC fits. It required a cabinet be built to hold the unit with compressor located remotely. It opens from the top and I added several inches of insulation. It's mostly used on sailboats so the food doesn't spill out when you tack. We lived aboard a sailboat for 15 years and were used to a top loader.

[TampaSteve]

Posting a reply to this thread as there aren't many active ITC threads on the Internet that are recent.

My experience is that recently when my mechanical thermostat starting acting like it was failing (Isotherm Cruise 219) I took a chance and replaced with the ITC. (I am aware that my Secop controller is now reprogrammed so I can't go back without swapping it.)

So far some goods and bads. The bad, which some may find good, is that it runs a very narrow cooling cycle now of a little more than one degree (see pic below), maintaining an almost constant temperature with short (20 minute) cycles.

The mechanical thermostat had a much larger range of about 4-5 degrees. During the longer off cycle, the accumulated frost melted and ran down the drain conveniently. This was a killer "feature" for my RV, basically no defrosting ever.

So I am concerned that these shorter cycles may leave the fridge frosting excessively, which I find a big problem while traveling.

My past experience with the ITC was poor, possibly because I didn't understand it or my fridge well. I am hoping the second try is better.

For this second try I was careful to turn battery protection to the lowest level. That will allow it to run full speed at 12.4 volts or more. That sounds like a really low SOC but in practice I found that when I run my AC occasionally off lithium batteries - that can drop the voltage dramatically. I have seen it as low as 12.5 with 150 amp load.

Basically I consider the Fridge the most critical thing in the RV. I want it running at 3500 rpm always, and I don't want it to ever shut down. (My BMS will save me if I somehow screw up and let the batteries discharge.)

I can't worry about energy usage as sometimes its 100+ degrees and I just want the temperature to remain in a safe zone.

The other good is, I like the remote display (dimmed it with a blackout sticker) and the ability to tweak settings without opening.

I'm headed out for some hot weather soon so I guess I will get some practical feedback from the ITC in the coming weeks.

But so far so good for me. The thing does work, albeit it probably offers a narrow set of potential advantages for most.

[GeorgeRa]

Originally Posted by TampaSteve

Posting a reply to this thread as there aren't many active ITC threads on the Internet that are recent.

My experience is that recently when my mechanical thermostat starting acting like it was failing (Isotherm Cruise 219) I took a chance and replaced with the ITC. (I am aware that my Secop controller is now reprogrammed so I can't go back without swapping it.)

So far some goods and bads. The bad, which some may find good, is that it runs a very narrow cooling cycle now of a little more than one degree (see pic below), maintaining an almost constant temperature with short (20 minute) cycles.

The mechanical thermostat had a much larger range of about 4-5 degrees. During the longer off cycle, the accumulated frost melted and ran down the drain conveniently. This was a killer "feature" for my RV, basically no defrosting ever.

So I am concerned that these shorter cycles may leave the fridge frosting excessively, which I find a big problem while traveling.

My past experience with the ITC was poor, possibly because I didn't understand it or my fridge well. I am hoping the second try is better.

For this second try I was careful to turn battery protection to the lowest level. That will allow it to run full speed at 12.4 volts or more. That sounds like a really low SOC but in practice I found that when I run my AC occasionally off lithium batteries - that can drop the voltage dramatically. I have seen it as low as 12.5 with 150 amp load.

Basically I consider the Fridge the most critical thing in the RV. I want it running at 3500 rpm always, and I don't want it to ever shut down. (My BMS will save me if I somehow screw up and let the batteries discharge.)

I can't worry about energy usage as sometimes its 100+ degrees and I just want the temperature to remain in a safe zone.

The other good is, I like the remote display (dimmed it with a blackout sticker) and the ability to tweak settings without opening.

I'm headed out for some hot weather soon so I guess I will get some practical feedback from the ITC in the coming weeks.

But so far so good for me. The thing does work, albeit it probably offers a narrow set of potential advantages for most.

Where did you placed the ITC temperature sensor and temperature gauge?

[TampaSteve]

Originally Posted by GeorgeRa

Where did you placed the ITC temperature sensor and temperature gauge?

I drilled the hole in the back of the fridge and quite low for the ITC probe and put it where recommended. I've considered that if I move it closer to where the old thermostat is (would leave an ugly wire in the fridge) that might lengthen the cycles.

My BlueTooth temperature sensor is closer to the mechanical thermostat, so runs slightly warmer.

[booster]

The cruise 219 is a massive frig compared to our and George's cruise 85s.


Looks like a two door setup with unknown location for the evaporator. The cold air to the frig may be adjustable, even. Probably a larger compressor also. A big frig like that would have completely different airflow issues than our small, usually packed pretty full, ones as it would likely have a lot of area for the cold air to spread out in it and get to the lower areas.


The one degree cycling is far from we saw with ours which had more than our mechanical thermostat by quite a bit. Maybe they have improved them for frig use as a wide range like ours had would probably work best for a freezer location for the temp sensor.


If energy use is of no concern, you have a lot more options about speeds and such. Higher compressor speeds will shorten the run periods.

[TampaSteve]

Yes, bigger compressor - BD50-F.

I emailed support in Italy before drilling and they said I would miss the evaporator where I drilled.

The tight temperature range did pique my interest vs the wide range reported. I have the opposite problem; I would like to widen it a bit.

Originally Posted by booster

The cruise 219 is a massive frig compared to our and George's cruise 85s.


Looks like a two door setup with unknown location for the evaporator. The cold air to the frig may be adjustable, even. Probably a larger compressor also. A big frig like that would have completely different airflow issues than our small, usually packed pretty full, ones as it would likely have a lot of area for the cold air to spread out in it and get to the lower areas.


The one degree cycling is far from we saw with ours which had more than our mechanical thermostat by quite a bit. Maybe they have improved them for frig use as a wide range like ours had would probably work best for a freezer location for the temp sensor.


If energy use is of no concern, you have a lot more options about speeds and such. Higher compressor speeds will shorten the run periods.

[booster]

Originally Posted by TampaSteve

Yes, bigger compressor - BD50-F.

I emailed support in Italy before drilling and they said I would miss the evaporator where I drilled.

The tight temperature range did pique my interest vs the wide range reported. I have the opposite problem; I would like to widen it a bit.

If the evaporator is in the back wall of the frig like it appears to be from the pic and your description, moving it away from that area to get the sensor further away from the evaporator should lengthen your run times. The sensor is probably cooling from the back wall with the compressor instead of the air in the frig. If the evaporator is way up by the freezer, then moving it may not help as much.

[GeorgeRa]

Originally Posted by booster

If the evaporator is in the back wall of the frig like it appears to be from the pic and your description, moving it away from that area to get the sensor further away from the evaporator should lengthen your run times. The sensor is probably cooling from the back wall with the compressor instead of the air in the frig. If the evaporator is way up by the freezer, then moving it may not help as much.

I agree, if the back wall is sheet metal directly attached to the evaporator than there is practically no time lag for this sensor location. Similarly, to electromechanical thermostat capillary bulb located directly on the cold plate. Agree, cycling could be control by relocating the temperature probe.

[TampaSteve]

Thanks that is what I am thinking. I'm traveling in the RV tomorrow for a while and hopefully its OK for now, if not I will relocate it, except I filled the hole with silicone so it may not let go right away.