Increasing Airflow through Condenser.
The new DC only compressor fridge I will soon have in my possession has a 92 mm computer muffin fan pulling air through only a portion(~85%) of the ~120mm tall condenser. It then blows this warmed a...
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Sorry Bdosbourn, I just reread this thread, and saw you already listed your condenser fan as 92 mm and 1.8 watts as the only visible markings on it.
From all the 92mm fans I can find online that claim this consumption, the CFM rating is likely 38 to 44 cfm.
This, along with the other reports of 92mm ~40 cfm condenser fans on other Danfoss powered fridges in the 2.2 cubic foot range gives me the confidence to try the Low noise adapter/ resistor which came with my Noctua fan and drops the minor fan noise to inaudible and CFM to 43 from 54.
I just pulled out all my smaller fans and tested their current draw, and how hot the hub motors got while running for a few minutes in ambient air.
Three different 40mm fan's hubs were 3 to 5 f degrees hotter than ambient. The 50 mm fan rated at 13 cfm and pulling 0.08 amps was nearly 7 to 8 degrees hotter than ambient. No doubt the hub motors are cooled by their own induced airflow as well.
You say you have a 50 mm fan rated at 17 cfm. It's hub must get even hotter, and transfer more heat to the box which then must be removed and thus add to the overall a/h Consumption.
I just ordered the 0.03a 40 mm Sunon I linked to above. Your tests prove that internal fans do increase battery consumption by the fridge itself, and it must be due to the minor heat they generate. It would not be easy for me to replicate that test and I don't feel the need, as it makes sense.
My Duty Cycle tests always show that internal box temps increase whenever I remove the fan from my freezer and I have to crank the T stat to a minimum of 3 out of 7 to keep them under 40. I have not thoroughly tested the duty cycle without the fan as I always wind up putting the fan back inside the freezer and dial it back below 3. I have not removed/ disconnected the fan when everything was already fully chilled and left it overnight. There is no doubt the fan helps in box cool down and quickens cool down of warmer items placed within.
I can now repeat the 'mystifying' results I alluded to in earlier posts by cranking the fridge up during the day and back off the t stat at night with a mostly full fridge with items already cooled within for many hours. If the fridge is less than 50% full I cannot get the OFF times to last more than 13 minutes, even if the duty cycle drops to 10%. Any things placed in the box recently, even cool/cold items from supermarkets, throw the steady pattern of cycles way off for upto 8 hours.
I find a setting of 2 out of 7 on the dial keeps the interior under 40f upto 70 ambient, and I need 2.5 to 3 at 85f ambient to keep it below 38f. It is when I crank it back from 3 to 2 late sub 64f evening that I get the 3-5 minute on 20 to 25+ minute off duty cycles until the next mid morning.
If I leave it on '3' overnight in low 60/ high 50f ambient, the interior drops to the low 30's and it runs about 5 minutes on 15 to 18 minutes off. This is with the 0.07a 4.6 cfm Delta fan in the freezer running 24/7.
My louvered vent behind the fridge is basically force fed by the condenser fan which is pulling air from the floor below the fridge. Whenever the compressor is running, I can feel a good flow of warmed air being expelled out the louvered vent.
I have not yet made the interior cabinet vent to allow the forced warmed air to enter the living space, and close off the electrically operated sliding window behind the louvered vent/fridge for wintertime temperatures
Currently, warmed/recycled air cannot be recycled into the cooling unit tunnel, and no other fans are needed to exhaust the compartment behind the fridge.
I am pretty sure I've now done everything to insure the fridge is as efficient as possible. I'll probably just leave the new 40mm maglev interior fan to run 24/7 too. It has to create a lot less heat than the 50mm 17 cfm fan which increases your fridge amp draw by 1 amp over 24 hours, and it consuming only 0.03 amps itself is pretty insignificant.
From all the 92mm fans I can find online that claim this consumption, the CFM rating is likely 38 to 44 cfm.
This, along with the other reports of 92mm ~40 cfm condenser fans on other Danfoss powered fridges in the 2.2 cubic foot range gives me the confidence to try the Low noise adapter/ resistor which came with my Noctua fan and drops the minor fan noise to inaudible and CFM to 43 from 54.
I just pulled out all my smaller fans and tested their current draw, and how hot the hub motors got while running for a few minutes in ambient air.
Three different 40mm fan's hubs were 3 to 5 f degrees hotter than ambient. The 50 mm fan rated at 13 cfm and pulling 0.08 amps was nearly 7 to 8 degrees hotter than ambient. No doubt the hub motors are cooled by their own induced airflow as well.
You say you have a 50 mm fan rated at 17 cfm. It's hub must get even hotter, and transfer more heat to the box which then must be removed and thus add to the overall a/h Consumption.
I just ordered the 0.03a 40 mm Sunon I linked to above. Your tests prove that internal fans do increase battery consumption by the fridge itself, and it must be due to the minor heat they generate. It would not be easy for me to replicate that test and I don't feel the need, as it makes sense.
My Duty Cycle tests always show that internal box temps increase whenever I remove the fan from my freezer and I have to crank the T stat to a minimum of 3 out of 7 to keep them under 40. I have not thoroughly tested the duty cycle without the fan as I always wind up putting the fan back inside the freezer and dial it back below 3. I have not removed/ disconnected the fan when everything was already fully chilled and left it overnight. There is no doubt the fan helps in box cool down and quickens cool down of warmer items placed within.
I can now repeat the 'mystifying' results I alluded to in earlier posts by cranking the fridge up during the day and back off the t stat at night with a mostly full fridge with items already cooled within for many hours. If the fridge is less than 50% full I cannot get the OFF times to last more than 13 minutes, even if the duty cycle drops to 10%. Any things placed in the box recently, even cool/cold items from supermarkets, throw the steady pattern of cycles way off for upto 8 hours.
I find a setting of 2 out of 7 on the dial keeps the interior under 40f upto 70 ambient, and I need 2.5 to 3 at 85f ambient to keep it below 38f. It is when I crank it back from 3 to 2 late sub 64f evening that I get the 3-5 minute on 20 to 25+ minute off duty cycles until the next mid morning.
If I leave it on '3' overnight in low 60/ high 50f ambient, the interior drops to the low 30's and it runs about 5 minutes on 15 to 18 minutes off. This is with the 0.07a 4.6 cfm Delta fan in the freezer running 24/7.
My louvered vent behind the fridge is basically force fed by the condenser fan which is pulling air from the floor below the fridge. Whenever the compressor is running, I can feel a good flow of warmed air being expelled out the louvered vent.
I have not yet made the interior cabinet vent to allow the forced warmed air to enter the living space, and close off the electrically operated sliding window behind the louvered vent/fridge for wintertime temperatures
Currently, warmed/recycled air cannot be recycled into the cooling unit tunnel, and no other fans are needed to exhaust the compartment behind the fridge.
I am pretty sure I've now done everything to insure the fridge is as efficient as possible. I'll probably just leave the new 40mm maglev interior fan to run 24/7 too. It has to create a lot less heat than the 50mm 17 cfm fan which increases your fridge amp draw by 1 amp over 24 hours, and it consuming only 0.03 amps itself is pretty insignificant.
