Isotherm Cruise 85 caput.

[booster]

Congratulation, nice to have a new and working fridge. How loud is your thermostat? How do you measure compressor RPM?

I don't hear it at all, even with aids, but I spent 50 years in noisy factories and there is a familiar history of hearing loss, so you can't go by me. I can feel the click in the thermostat knob so those with very sensitive hearing probably could hear it. The new, thicker, door may also quiet it down a bit.



I don't know of any way of directly measuring compressor speed. You might get close with measuring whatever the do to control the speed at the motor but unlikely to know what you are seeing. I am going strictly be the compressor rpm chart vs resistor ohms chart they give. I was at zero ohms, which should be 2000 rpm and the lowest they recommend.


The 2.2 would be just under 53ah/day if 24/7 run time and that is probably close to what we saw in Zion when the days were 100-105*F and the frig was on the full sun side. I had guessed in the 45ah range, as we had other loads going like the two circulating fans and ceiling vent running all day also. IIRC we used about 65ah per day there. I was quite amazed that it kept up on the lowest compressor speed.

 

[GeorgeRad]

I just run SECOP faults retrieval process with LED – no faults. So, getting 24VDC (measured 27VDC) supply for the fridge light is not reflected in faults.

Based on all tests I am ready to make a decision:

1. New SECOP, 27V makes me nervous, with ICT. Reinstalling SECOP could be difficult but duable. No noise.

2. Capillary, could be difficult to reinstall the bulb and the thermostat, I don’t think I have all parts from the old one.

 

[booster]

I just run SECOP faults retrieval process with LED – no faults. So, getting 24VDC (measured 27VDC) supply for the fridge light is not reflected in faults.

Based on all tests I am ready to make a decision:

1. New SECOP, 27V makes me nervous, with ICT. Reinstalling SECOP could be difficult but duable. No noise.

2. Capillary, could be difficult to reinstall the bulb and the thermostat, I don’t think I have all parts from the old one.

I do think you have a third option, if you have the space to do it, and that would be to add a Rainbird type themostatic relay controller. The space thing, and possibly extra power use, ruled that out for us for the most part. You would just need to put a speed resistor in the line also, or a selectable speed switch, and connect it as a mechanical thermostat would be connected.

 

[GeorgeRad]

I am using the Inkbird to control the cooling fan in the electrical cabinet. This controller draws about 3W so I turn it on in hot weather only. It is wired into my battery saving switch which controls the control panel LED illumination and other not critical loads. Unfortunately, I don’t have room for its depth in possible place below the galley countertop.

I just found this information about advantages of 101N0510 vs older 101N0500 which I have, see the picture.

I spent some time today with someone from the service department discussing my options:
- Their information about why I have 24V for the light bulb was rather fuzzy and contradicting their previous info. Danfoss instruction for 101N0500 clearly states to use 12V bulb for either 12V or 24V batteries on their spec sheet “Lamp (optional, Fig. 1) A 12V DC 5-Watt lamp (10) can be connected between the terminals A and C. The output voltage between the terminals A and C is always regulated to 12V DC. A 12V DC lamp must be used for both 12V and 24V power supply systems. The lamp output can supply a continuous current of 0.5A avg.”

- He claimed efficiency gain up to 20% using ITC vs electromechanical thermostat. Unfortunately, no details and I couldn’t find any review on line with efficiency gains.

I am going to get a new 101N0510 controller with an ITC and experiment with a location of the sensor including freezer. The risk with ITC is possible negative experience which you had but ITC has a lot of things I like:


- Turning the product on and off without opening the refrigerated
compartment
- Instant display of the actual temperature inside the refrigerated
compartment
- Display and/or change of the set temperature with a simple press of the up
and down keys
- Selection of permanent energy savings operation
- Instant display of any operating faults
- The product is equipped with a Soft Start function. The number of
compressor revolutions is kept to the minimum allowed for approximately
30 sec. at every start of the compressor. This allows you to balance the
internal pressures on the gas circuit, preventing possible compressor blocks
and allowing the control unit to compare and process all the data set and
collected and decide whether to keep an energy-saving configuration or
increase cooling power.
- Possibility of selecting and checking the temperature within a wide-scale
range from that of the refrigerator and that of the freezer
- Possibility of selecting temperature indication in Celsius or Fahrenheit
- Possibility of operation with the maximum level of performance or energy
saving
- Possibility of selecting 3 different battery protection levels and resulting
compressor operation
- Possibility of setting temperature offset for 3 different temperature ranges
- Possibility of sub-cooling in the event of an available surplus of energy

 

[booster]

Responses in Blue in your quote

I am using the Inkbird to control the cooling fan in the electrical cabinet. This controller draws about 3W so I turn it on in hot weather only. It is wired into my battery saving switch which controls the control panel LED illumination and other not critical loads. Unfortunately, I don’t have room for its depth in possible place below the galley countertop.

I just found this information about advantages of 101N0510 vs older 101N0500 which I have, see the picture.

I spent some time today with someone from the service department discussing my options:
- Their information about why I have 24V for the light bulb was rather fuzzy and contradicting their previous info. Danfoss instruction for 101N0500 clearly states to use 12V bulb for either 12V or 24V batteries on their spec sheet “Lamp (optional, Fig. 1) A 12V DC 5-Watt lamp (10) can be connected between the terminals A and C. The output voltage between the terminals A and C is always regulated to 12V DC. A 12V DC lamp must be used for both 12V and 24V power supply systems. The lamp output can supply a continuous current of 0.5A avg.”

- He claimed efficiency gain up to 20% using ITC vs electromechanical thermostat. Unfortunately, no details and I couldn’t find any review on line with efficiency gains.

I am going to get a new 101N0510 controller with an ITC and experiment with a location of the sensor including freezer. The risk with ITC is possible negative experience which you had but ITC has a lot of things I like:


- Turning the product on and off without opening the refrigerated
compartment Sort of, it shuts off the display and running of cooling. It doesn't go to no power or shut off the light, so is not good for storage as it still uses power and you can't ventilate the box. I just added a power on/off switch with an LED indicator of on.
- Instant display of the actual temperature inside the refrigerated
compartment Yes, but it is 2*F increments that are rounded from 1*C readings, it appears. Not particularly accurate. We use a wireless thermometer that is just fine and in 1/10*F increments and has a lithium rechargeable frig sensor.
- Display and/or change of the set temperature with a simple press of the up Yes, but in 2* increments so tough if you are trying to get close to 32* or near max at 41*.
and down keys
- Selection of permanent energy savings operation They grossly overestimate how good the savings are in either automatic or ECO. We used way, way more power in automatic that our old frig ever did once we turned down the speed, or even before. In ECO mode they say all over the place that they turn down the speed to minimum, which is 2000rpm per Secop literature, but when I saw where the amps were I went looking for an actual spec and it says they turn it down to 2500rpm. The stock speed for the mechanical was set by a 466 ohm resistor which would be about 2750rpm so very little saving there. We run at 2000 rpm almost all the time without issue as it is a small frig, added insulation, and has very good ventilation. The old frig cooled in 100*F+ in Zion while in the sun at 2000rpm. You saw the testing we did before we put it in and it used about 15% less energy on mechanical thermostat than on ECO with the ITC. I never tested the overcooling as we wouldn't want it anyway as it can damage some fresh vegetables and such. There were also a number of posts on the boater forums that said once they put it in overcooling they couldn't get it to come out without shutting down the power to the frig so glad I didn't try it.
- Instant display of any operating faults Yes
- The product is equipped with a Soft Start function. The main reason I went with the ITC against my instincts in the first place, along with a remote display. The number of
compressor revolutions is kept to the minimum allowed for approximately
30 sec. at every start of the compressor. This allows you to balance the
internal pressures on the gas circuit, preventing possible compressor blocks
and allowing the control unit to compare and process all the data set and
collected and decide whether to keep an energy-saving configuration or
increase cooling power.
- Possibility of selecting and checking the temperature within a wide-scale
range from that of the refrigerator and that of the freezer Yes, but if you go to temps you might need to reset the display temp correction factor as it has 3 ranges of temps, each with their own correction. I never tested if you can set them all up front or not, but I would hope you can.
- Possibility of selecting temperature indication in Celsius or Fahrenheit Yes, but F is a rounded off C reading converted and displays in 2* increments
- Possibility of operation with the maximum level of performance or energy
saving See above all settings, except maybe the overcooling, used considerably more energy than the mechanical does.
- Possibility of selecting 3 different battery protection levels and resulting
compressor operation
- Possibility of setting temperature offset for 3 different temperature ranges Yes
- Possibility of sub-cooling in the event of an available surplus of energy Yes

They don't talk about temp control but we found the hysteresis to be nearly as large as our usable range at 6+ *F. Very hard to zero in on 34-40*F, preferrable 37-38*F, when you have over 6* swing and 2*F increments to set.


Yep, the ITC was incredibly disappointing to me, and most of the good things they claimed, particularly about energy use were just not correct.


The mechanical is up and running now and doing the long time needed zeroing in on best dial setting as the 1 gallon of liquid in the box stabilizes very, very slowly. I will then check freeze temp, which probably will be 6*F. Will repeat test with same frig temp and drip tray out to see freezer temp, but it will probably be in 20*F range, which is considerably more efficient and suits us just fine. If the freezer comes out still colder than we like, I will probably move the bulb to the top of freezer box instead of the inside stock location as that is how I had the old frig and it worked very well. Removing the tray would be our first choice as we can just put it back in if we do happen to have something we want to keep colder in the freezer, although doesn't happen often.


I have not been able to find a standalone or addon soft start for these compressors, but starting at 2000rpm should help at least some.


All said, though, if you decide to try the ITC I wish you the best of luck with it and hope it meets the criteria that you desire it to.


Thanks for the information on the Rainbird power use. I have seen so many posters various places saying that type of control uses miniscule amounts of energy, most stating miliamps (which it may do while not activated).

 

[GeorgeRad]

Responses in Blue in your quote






They don't talk about temp control but we found the hysteresis to be nearly as large as our usable range at 6+ *F. Very hard to zero in on 34-40*F, preferrable 37-38*F, when you have over 6* swing and 2*F increments to set.


Yep, the ITC was incredibly disappointing to me, and most of the good things they claimed, particularly about energy use were just not correct.


The mechanical is up and running now and doing the long time needed zeroing in on best dial setting as the 1 gallon of liquid in the box stabilizes very, very slowly. I will then check freeze temp, which probably will be 6*F. Will repeat test with same frig temp and drip tray out to see freezer temp, but it will probably be in 20*F range, which is considerably more efficient and suits us just fine. If the freezer comes out still colder than we like, I will probably move the bulb to the top of freezer box instead of the inside stock location as that is how I had the old frig and it worked very well. Removing the tray would be our first choice as we can just put it back in if we do happen to have something we want to keep colder in the freezer, although doesn't happen often.


I have not been able to find a standalone or addon soft start for these compressors, but starting at 2000rpm should help at least some.


All said, though, if you decide to try the ITC I wish you the best of luck with it and hope it meets the criteria that you desire it to.


Thanks for the information on the Rainbird power use. I have seen so many posters various places saying that type of control uses miniscule amounts of energy, most stating miliamps (which it may do while not activated).

Thank you for the very comprehensive information. Helpes me a lot in my decision process. With your details the list of ICT marketing goodies shrunk considerably, on off switch is truly a joke.

My temperature measurements with SEC on setting #6 – coldest (fridge empty) were very predictable if fridge was working. In the fridge temperature from min to max took about 45 min and from hot to cold about 35 min. The fridge temperature swing was very good at 2.9*, but only in the #6 set point. But still temperature from 39 to 41.9*F was way too high.

These are swings with my SEC.
Freezer (-13.3) - 32.2, swing 45.5
Fridge 39 - 41.9, swing 2.9

My compressor works, it can cool cold plate down to -13.3* in 35min. The fridge is 8 years old, so it has a few more years to go. Danfoss controller lightbulb voltage is 27VDC, well, so it is but it works with 24V LED. Reinstalling an electromechanical thermostat on the existing fridge could be the best option. Will get back to this project in a couple of weeks.

Which wireless thermometer you use, my Sensor-Push is good but, on the road I would prefer permanent display, not a smart phone.

 

[booster]

We have this one.


https://www.amazon.com/gp/product/B07CSV14Y2/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1


We got it a couple of years ago and it has been quite good. The rechargeable transmitter is nice. It is sealed but we also put it in a lightweight ziplock bag as that is what we always have done because the condensation is hard on them.


We have gone through a few of other brands over the years and the one that said for frigs was the worst. Lasted weeks. We then started getting cheapo Menards ones that would last a couple of years, but were $8. The lithium batteries for the transmitter did add up though as they weren't rechargeable. We get at least 3 weeks on a charge, probably more like 6 or 8 but we haven't been out that long. It does have an on/switch on the transmitter so you can shut if off to limit recharging.

 

[GeorgeRad]

We have this one.


https://www.amazon.com/gp/product/B07CSV14Y2/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1


We got it a couple of years ago and it has been quite good. The rechargeable transmitter is nice. It is sealed but we also put it in a lightweight ziplock bag as that is what we always have done because the condensation is hard on them.


We have gone through a few of other brands over the years and the one that said for frigs was the worst. Lasted weeks. We then started getting cheapo Menards ones that would last a couple of years, but were $8. The lithium batteries for the transmitter did add up though as they weren't rechargeable. We get at least 3 weeks on a charge, probably more like 6 or 8 but we haven't been out that long. It does have an on/switch on the transmitter so you can shut if off to limit recharging.

Thank you.

This simple Spanish electronic thermostat AKO 13112 could fit in the space I have available in my galley; it is only 2” deep versus Inkbird which is 2.95”. AKO can display actual and set point temperatures.

Small Digital Temperature Controller | AKO-13120 Digital Thermostat

Small Digital Temperature Controller | AKO-13120 Digital Thermostat http://schindlertechnologies.com/wp-content/uploads/AKO-13XXX-EN.pdf

https://www.amazon.com/Inkbird-All-...9Y2xpY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU=

 

[GeorgeRad]

Ako 13112

Placed the order for the AKO 13112 12V thermostat. AKO is made by https://www.ako.com/ in Spain specialized in refrigeration. For peace of mind I will be getting a new SECOP 101N0510.

 

[booster]

Placed the order for the AKO 13112 12V thermostat. AKO is made by https://www.ako.com/ in Spain specialized in refrigeration. For peace of mind I will be getting a new SECOP 101N0510.

The specs show 3VA max, which I think is about .2 amps and that is similar to what I guessed the ITC was using when I had it running. Traditionally, the max readings were always quite a bit above actual, but with the thermostats the things I have seen may indicate otherwise. I assume power use is higher when activated so duty cycle would determine daily power use but could be as high as 5ah. We are down to only the propane detector on coach batteries, so our parasitic for it and the two monitors is .2 amps by comparison, but that is 24/7. It would likely be similar to your Rainbird as they all seem to be nearly identical in specs between brands.


Our testing is ongoing and running now at the low speed of 2000rpm, the frig runs colder at the same settings, no surprise there as the old one did that also. I have the thermostat loose now so I can tweak the range to match as the warmest I could get was just under 39* and it is good to be able to get to maybe 43* because in cold weather it will run colder by a bit because we use outdoor cooling air. This frig, with new freezer design benefits even more than the old one did when running without the drip pan. It may be as much as 20% change in energy use. I haven't checked the freezer to frig temps yet as I want to get stabilized at checkpoints of 41* and 38* so I can be consistent in that test. Interesting that I saw when I took the thermostat mount loose that the tube runs behind the frig liner and appears to be unremovable for all practical purposes. If it died, it would have to be just cut and a new one run inside the frig.


It is also a *C based unit, it appears, so it will have the same conversion rounding type issues as the ITC as it doesn't have a 1/10th digit, which would be nice. Our wireless is C* based also but has the 1/10 digit so definitely useful. At leas that unit looks like you can set 1*F increments which is much better than the 2*F the ITC had.

 

[GeorgeRad]

While waiting for SECOP controller I measured power consumption of the new AKO 13112 thermostat, with relay on, it just above 0.8W. Unit is small, it has programmable defrosting, hysteresis, calibration, etc., see the chart. Testing on the fridge soon.

 

[booster]

While waiting for SECOP controller I measured power consumption of the new AKO 13112 thermostat, with relay on, it just above 0.8W. Unit is small, it has programmable defrosting, hysteresis, calibration, etc., see the chart. Testing on the fridge soon.

Thanks, George, good information.


Based on duty cycle that would probably translate to maybe .2- .3amps average over time. About 4-7ah per day, which is not huge or small. We use in the 25-30ah for the frig most days on the road, at least with the old frig, so about a 25% increase which is significant for those that don't have a lot of battery capacity or solar. For comparison, per the Secop literature, the mechanical thermostat uses between 2 and 6 milliamps depending on the resistor value, so a big difference. Balancing point of what is most important to the user and system capacity, I think. Neither way would be right or wrong for everyone.

 

[GeorgeRad]

Thanks, George, good information.


Based on duty cycle that would probably translate to maybe .2- .3amps average over time. About 4-7ah per day, which is not huge or small. We use in the 25-30ah for the frig most days on the road, at least with the old frig, so about a 25% increase which is significant for those that don't have a lot of battery capacity or solar. For comparison, per the Secop literature, the mechanical thermostat uses between 2 and 6 milliamps depending on the resistor value, so a big difference. Balancing point of what is most important to the user and system capacity, I think. Neither way would be right or wrong for everyone.

I should have stated that in the off state the thermostat power draw is at 0.402W, so at 30% duty cycle average will be at 0.523W which is about 41mA at 12.8V. So for 24hrs the thermostat will consume less than 1Ah, I think.

 

[booster]

I should have stated that in the off state the thermostat power draw is at 0.402W, so at 30% duty cycle average will be at 0.523W which is about 41mA at 12.8V. So for 24hrs the thermostat will consume less than 1Ah, I think.

Gotcha, I missed the decimal point with the relay on. Does the display time out on that unit, the one I used at home does not. The ICT appeared to be using about .2 amps all the time. It had a very bright display that couldn't be shut off.

 

[GeorgeRad]

Sorry George, I lied to you.


The sensor bulb location is correct, but in stock form the screws come in from the top the box and are very hard to get at and turn. I tiny vise grip works well, IIRC. There are extruded, tapped holes in the plate that holds the sensor. I remember what I really did once I saw it.



When I put the replacement in back then, about 2-3 years after we got the frig, changed it a bit to make it easier if there was a next time.


I epoxied the screws in place in the top of the box and drilled out the extruded threads and used nuts and lock washers on the inside, basically remov the extruded area. I then put on the plate and tube over the screws and put on the nuts and washers. Easy to do in the future.

To pick a final thermostat I am looking how to replace capillary thermostat, original sensor bulb is mounted inside the freezer compartment in an aluminum bracket attached with 2 screws accessible from the top of the freezer box. I am not very willing to risk twisting the freezer box tubing to access these screws.

Searching for another, no drilling, sensor bulb mounting bracket didn’t bring results. An aluminum tape with good adhesive could work well.

 

[GeorgeRad]

I just finish two 24 hours tests of AKO 12112 thermostat, one with sensor inside the freezer (a la capillary thermostat) and the other one with sensor on the back side of the fridge compartment. Voltage 12.8V. Ambient temperature 62F. Thermostat set for 35F. Defrost cycle set for every 6 hours to 40F. Fridge empty.

Not perfeect test but good enough to see the difference of sensor location, not much.

Sensor in the freezer test took 171 Wh, in the fridge 167 Wh so practically no difference. AKO 12112 draws on idle 43mA and it was included in tests.

Based on these results I am not going to pursue electromechanical capillary thermostat and need to select between AKO 12112 or Isotherm ICT. Pluses and minuses on both.

 

[booster]

I just finish two 24 hours tests of AKO 12112 thermostat, one with sensor inside the freezer (a la capillary thermostat) and the other one with sensor on the back side of the fridge compartment. Voltage 12.8V. Ambient temperature 62F. Thermostat set for 35F. Defrost cycle set for every 6 hours to 40F. Fridge empty.

Not perfeect test but good enough to see the difference of sensor location, not much.

Sensor in the freezer test took 171 Wh, in the fridge 167 Wh so practically no difference. AKO 12112 draws on idle 43mA and it was included in tests.

Based on these results I am not going to pursue electromechanical capillary thermostat and need to select between AKO 12112 or Isotherm ICT. Pluses and minuses on both.

Nice test.



The 62* really helps the energy use compared to higher temps for energy use.


Was there any noticeable temp swing? It might be interesting to compare the swing to a standalone digital thermometer to see it they have the same response. I found the ICT to be quite different. The Emerson thermostat we had on the house for while actually fudged the temps to make it look warmer in the room than it was during morning temp recovery heat runs.



Did you get a measurement of how much power the control used with the relay on? That .043a looks like about 13wh per day.

 

[GeorgeRad]

Nice test.



The 62* really helps the energy use compared to higher temps for energy use.


Was there any noticeable temp swing? It might be interesting to compare the swing to a standalone digital thermometer to see it they have the same response. I found the ICT to be quite different. The Emerson thermostat we had on the house for while actually fudged the temps to make it look warmer in the room than it was during morning temp recovery heat runs.



Did you get a measurement of how much power the control used with the relay on? That .043a looks like about 13wh per day.

Thank you Booster,

Indeed, 62F shows low consumption.

These are temperature ranges on the temperature sensor located on the fridge floor. The tray under the freezer was removed. I didn’t write down the thermostat setpoint in the freezer but I ma pretty certain it was 25F.

Sensor in the freezer: 37.4 – 37.6F, range 0.2F, peak to peak cycling 7 min.
Sensor in the fridge: 37.3-38.9F, range 1.6F, peak to peak cycling 48 min.

From my previous measurament AKA drew with the relay on 63 mA, see the picture.

 

[booster]

Thank you Booster,

Indeed, 62F shows low consumption.

These are temperature ranges on the temperature sensor located on the fridge floor. The tray under the freezer was removed. I didn’t write down the thermostat setpoint in the freezer but I ma pretty certain it was 25F.

Sensor in the freezer: 37.4 – 37.6F, range 0.2F, peak to peak cycling 7 min.
Sensor in the fridge: 37.3-38.9F, range 1.6F, peak to peak cycling 48 min.

From my previous measurament AKA drew with the relay on 63 mA, see the picture.

Thanks George. With the sensor in freezer those are very short cycles even for cool ambient, I think. The large hysteresis of the mechanical thermostats gives them a break in cycle time and accounts for time to move heat from the frig to freezer, I think so frig stays consistent. If you decide to do the freezer location, I would increase the hysteresis on the control. The frig control hysteresis is quite good, and the 25* in the freezer are about what I saw with the tray out. It sure does give good use numbers though, don't you think?

 

[GeorgeRad]

Thanks George. With the sensor in freezer those are very short cycles even for cool ambient, I think. The large hysteresis of the mechanical thermostats gives them a break in cycle time and accounts for time to move heat from the frig to freezer, I think so frig stays consistent. If you decide to do the freezer location, I would increase the hysteresis on the control. The frig control hysteresis is quite good, and the 25* in the freezer are about what I saw with the tray out. It sure does give good use numbers though, don't you think?

I am leaning towards ICT, primarily due to easier interface, AKO menu needs manual. Sensor would be located on the back wall where my current SEC sensor is, it is possible SEC and ICT used the same sensor, I need to measure it.

My experiment with $10 generic capillary sensor was a fiasco, I couldn’t dial a working temperature.

I will use ICT for turning fridge on/off and have additional switch for the internal lamp mounted on the lamp housing.