Forum Discussion
jlaustin
Jun 14, 2010Explorer
DuroPower 3500ES Cooling Duct Update!
As previously posted, I had "torture tested" my DuroPower 3500ES LPG/Remote Start conversion by running the 15K BTU A/C's compressor on the fifth wheel continuously and observed the genset's alternator cooling air exhaust temps. In every case, before and after adding a duct to the alternator, the exhaust temps would inexorably climb to about 190 degrees within an hour - the duct just slowed the temp rise down for a few minutes. I terminated the test each time at 190 out of fear of damaging the alternator's wiring due to thermal breakdown as the Prof has explained in previous posts.
Here's what the duct looked like initially (that's it on the left - on the right is the muffler enclosure) - normally there is a metal/foam/Hardiebacker enclosure panel covering this area:
I decided to try forced air cooling to see if this would help. Marvin P Jones & Associates is a great source for power supplies, cooling fans, etc. I found these server fans in a set of four for the princely price of $9.95 (that's right ... all four for $9.95 total!)! They are rated at 25.47 cfm each/100+ cfm total and are intended for moderate pressurization. Each little unit has a 3-blade and a 5-blade fan in series:
Incredibly, the dimensions fit my duct almost with no alternation! I just had to snip off some plastic mounts on each end and put a filler strip on weatherstripping on one side and it fit perfectly! Here's a pic of the fans up inside the duct opening:
I used the original alternator cooling intake cap to reinforce the duct. I cut out all the louvers and just left the ring around the periphery so it would mate with the alternator perfectly - for now, some Gorilla tape around the periphery holds it in place - later, I'll probably drill and tap the alternator casing to accept some mounting flanges:
Now ... the best part of all! I wired the fans into the same switch on the alternator exhaust cooling vents that cuts "on" at about 150 degrees. (The switch also triggers the 500 cfm ventilation fan at the top of the genset.) I repeated the "torture test" with the A/C compressor continuously running. The duct fans dutifully kicked-in at 150 degrees. The cooling exhaust averaged 151-152 degrees and never climbed any higher - no matter how long the compressor ran! In fact, at times the fans could cool the switch down below 150 and this would cut them off! The ambient was 85 degrees with relatively high humidity ... actually slightly warmer than previous tests.
I feel confident my alternator cooling is satisfactory. It will still pay to keep an eye on it on an extreme day, however!
Regards,
John
As previously posted, I had "torture tested" my DuroPower 3500ES LPG/Remote Start conversion by running the 15K BTU A/C's compressor on the fifth wheel continuously and observed the genset's alternator cooling air exhaust temps. In every case, before and after adding a duct to the alternator, the exhaust temps would inexorably climb to about 190 degrees within an hour - the duct just slowed the temp rise down for a few minutes. I terminated the test each time at 190 out of fear of damaging the alternator's wiring due to thermal breakdown as the Prof has explained in previous posts.
Here's what the duct looked like initially (that's it on the left - on the right is the muffler enclosure) - normally there is a metal/foam/Hardiebacker enclosure panel covering this area:
I decided to try forced air cooling to see if this would help. Marvin P Jones & Associates is a great source for power supplies, cooling fans, etc. I found these server fans in a set of four for the princely price of $9.95 (that's right ... all four for $9.95 total!)! They are rated at 25.47 cfm each/100+ cfm total and are intended for moderate pressurization. Each little unit has a 3-blade and a 5-blade fan in series:
Incredibly, the dimensions fit my duct almost with no alternation! I just had to snip off some plastic mounts on each end and put a filler strip on weatherstripping on one side and it fit perfectly! Here's a pic of the fans up inside the duct opening:
I used the original alternator cooling intake cap to reinforce the duct. I cut out all the louvers and just left the ring around the periphery so it would mate with the alternator perfectly - for now, some Gorilla tape around the periphery holds it in place - later, I'll probably drill and tap the alternator casing to accept some mounting flanges:
Now ... the best part of all! I wired the fans into the same switch on the alternator exhaust cooling vents that cuts "on" at about 150 degrees. (The switch also triggers the 500 cfm ventilation fan at the top of the genset.) I repeated the "torture test" with the A/C compressor continuously running. The duct fans dutifully kicked-in at 150 degrees. The cooling exhaust averaged 151-152 degrees and never climbed any higher - no matter how long the compressor ran! In fact, at times the fans could cool the switch down below 150 and this would cut them off! The ambient was 85 degrees with relatively high humidity ... actually slightly warmer than previous tests.
I feel confident my alternator cooling is satisfactory. It will still pay to keep an eye on it on an extreme day, however!
Regards,
John
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