DEF Tank Digitial Temp, road test with photos

[brobox]

Did a short road test on the way to Cummins this morning with a digital thermometer sensor mounted to the DEF tank as close the heat exhaust as possible. If 125 degrees is the danger point for DEF and the DEF sensor, this test was not favorable and there is an engineering problem.

It is 6 miles from my storage hanger via US 41 at 55 MPH to Cummins. This was at 7:30 AM outside temp 86 degrees

Photo # 1 is the digital thermometer sensor mount to the DEF tank with the sensor opening point to the DEF tank and fluid.

Photo # 2 is at 55 mph, ambient temperature 86 degrees at 7:30 am. The DEF tank temperature is 121 degree while still cool outside and at cruising speed with plenty of airflow.

Photo #3 was stopped at a signal for 2 min. 5 seconds, the temperature had already climbed to 124 degrees without airflow. only 1 degree from the critical point and it's only 7:30 am

Photo # 4 was after backing into my hanger at 9:30 am, with about 3 minutes of idle time backing into an enclosed metal aircraft hanger while centering and parking the MH. The temperature is now 131 degrees, 6 degrees past the critical 125 degrees for the DEF system.

I went to take the fluid temperature with my digital gun, but the battery was dead. That test will be done after the trip to Ft Lauderdale next week along with mid afternoon road temp test.

One thing that is concerning is there seems to be so much engineering into preventing DEF from freezing in the winter, but no method of cooling DEF in the summer when RV'ers travel. I am sure the engineers at Spartan have much more sophisticated equipment than my Walmart digital outdoor thermometer and can answer that question?

[flyboy013]

Given that the thermistor is measuring the ambient temperature at the DEF tank and isn't as accurate as measuring the DEF fluid itself, I was wondering if you have the ability to read data from the J1939 bus? I did this on my coach last weekend with a BlueFire adapter, but I see from your signature that you have a digital dash. Another user captured the below picture from their digital dash and it contains the DEF temperature.



If you look for the PGN with an ID of 65110 (3rd line), you will see that the second data byte is hex 42. This equates to 66 decimal. Subtract 40 to get the Celsius temperature and then convert to fahrenheit yields a temperature of 78.8 degrees fahrenheit. (66 - 40) * 9 / 5 + 32.

Just a thought to get a more accurate reading of the DEF temperature itself.

[brobox]

Sorry, I don't do engineer but I will try. I am just doing simple mechanic. If it's hot outside, it's going to be hot inside without air conditioning. I will do a digital scan with an Infrared Laser Thermometer when we arrive in Ft. Lauderdale next week. I think a direct reading on the fluid is going to be pretty accurate. So far the unscientific test I have done, the DEF container gets hot. I do not see how it will be much cooler inside with a full day of travel in 95 degree weather. Hopefully I am wrong.

[seeg]

Originally Posted by flyboy013

Given that the thermistor is measuring the ambient temperature at the DEF tank and isn't as accurate as measuring the DEF fluid itself, I was wondering if you have the ability to read data from the J1939 bus? I did this on my coach last weekend with a BlueFire adapter, but I see from your signature that you have a digital dash. Another user captured the below picture from their digital dash and it contains the DEF temperature.

Attachment 337846



If you look for the PGN with an ID of 65110 (3rd line), you will see that the second data byte is hex 42. This equates to 66 decimal. Subtract 40 to get the Celsius temperature and then convert to fahrenheit yields a temperature of 78.8 degrees fahrenheit. (66 - 40) * 9 / 5 + 32.

Just a thought to get a more accurate reading of the DEF temperature itself.

Hmm, law school isn’t much help here. You lost me at “hex 42”. Seems it wouldn’t be much trouble to present this sort of info in a more understandable format so it would be of some use to the end user.

Originally Posted by Smitty3509

I was thinking of adding an inline brass manual valve on one of the heater hoses. Just keep it turned off during the summer.

[wnytaxman]

Chuck, did you check the DEF to see if it is still in the 32% range? I would be curious as to whether or not the percentages were in range.

[tom chelbana]

After driving for 2 or more hours with outside temps at 90 degrees plus we have found cabinet temps at 145 to 155 degrees. With the DEF fluid full getting reading of 130 degrees. With insulation, exhaust wrap and drier vent scoop for outside air those temps are today 122 degrees in cabinet area and the DEF fluid 110 degrees.

[Archer2]

I know one thing for sure from your experiment Chuck. That is the spread between the temp of the DEF tank vs ambient is a lot! There are only 3 things that could be adding heat. Radiant heat from the engine and exhaust system, Hot DEF returning from the injector and un-commanded and unwanted heat from the engine coolant heat exchanger in the tank. If it’s mostly from the proximity to the DPF/SCR module you have to wonder what it gets to be during a 1200 degree regen cycle. I’m not too impressed with the design of this system as a good place to put sophisticated electronics. Anyway, thanks Chuck for the data points and thanks for taking the trouble to run the test.

[brobox]

Originally Posted by wnytaxman

Chuck, did you check the DEF to see if it is still in the 32% range? I would be curious as to whether or not the percentages were in range.

Yes I did, right at 32.5. I am also going to add a jug of fresh DEF today so the tank is full past the temperature sensor for the heat test when we run over to Ft Lauderdale.

[brobox]

Originally Posted by tom chelbana

After driving for 2 or more hours with outside temps at 90 degrees plus we have found cabinet temps at 145 to 155 degrees. With the DEF fluid full getting reading of 130 degrees. With insulation, exhaust wrap and drier vent scoop for outside air those temps are today 122 degrees in cabinet area and the DEF fluid 110 degrees.

Tom I have watched your posts and mod with interest. It was one of your posts that prompted me to try this setup on the Entegra. The Entegra tank I think is more in the open than the Newmar tank. But we have all of the exhaust system very close to the tank. In just that short 6 mile test, It looks like there is a heat issue that is being brought up being one of the problem of the DEF sensors.

Originally Posted by Archer2

I know one thing for sure from your experiment Chuck. That is the spread between the temp of the DEF tank vs ambient is a lot! There are only 3 things that could be adding heat. Radiant heat from the engine and exhaust system, Hot DEF returning from the injector and un-commanded and unwanted heat from the engine coolant heat exchanger in the tank. If it’s mostly from the proximity to the DPF/SCR module you have to wonder what it gets to be during a 1200 degree regen cycle. I’m not too impressed with the design of this system as a good place to put sophisticated electronics. Anyway, thanks Chuck for the data points and thanks for taking the trouble to run the test.

I am beginning to see and believe your theory on the heat issue. My test may not be scientific enough for some, but I think after I am able to take the temperature of the fluid with the Infrared thermometer I think that we will see that outside temperature is going to be the same temperature of the fluid after an hour on the road. There is absolutely nothing protecting or cooling the fluid inside of the tank.

[Gary.Jones]

Very interesting thread...

The main 5 or 6" exhaust pipe (covered with heat shield comes right through the top of my DEF tank compartment). The compartment is completely open at the bottom for air passage but I have no idea how much air circulation is actually in that compartment so interesting data!

Gary

[Archer2]

Originally Posted by brobox

I think that we will see that outside temperature is going to be the same temperature of the fluid after an hour on the road. There is absolutely nothing protecting or cooling the fluid inside of the tank.

Chuck, when you said outside temp in the quote you mean the outside of the tank? Not the outside air ambient temp, right? If I understand you right then I agree 100%

[brobox]

Originally Posted by Archer2

Chuck, when you said outside temp in the quote you mean the outside of the tank? Not the outside air ambient temp, right? If I understand you right then I agree 100%

Yes outside of the tank. The ambient temperature was 86 degrees.

[brobox]

Originally Posted by Gary.Jones

Very interesting thread...

The main 5 or 6" exhaust pipe (covered with heat shield comes right through the top of my DEF tank compartment). The compartment is completely open at the bottom for air passage but I have no idea how much air circulation is actually in that compartment so interesting data!

Gary

Just took this photo showing how close the DEF tank with the temperature sensor attached is to the SRC unit and exhaust. 10 inch to the side of the tank.

[flyboy013]

Originally Posted by brobox

Just took this photo showing how close the DEF tank with the temperature sensor attached is to the SRC unit and exhaust. 10 inch to the side of the tank.

I took the below pictures at the Newmar International Rally last week. They provide a good view of how close the DEF tank is to the SCR. The first one is a Freightliner chassis, the second is a Spartan K3.