MEGAWATT Cooling Fan Questions
It's cooling fan modification time. The louvered cutout on the aluminum case has 4 spot-welds in the hub. Any idea why? I am planning on full-circle cut-out the holes on both Megawatts, then use...
Forum Discussion
Senor Golden HVAC, the fans in question are the OEM Megawatt fans. Playing around with the forty or so different models of fans I have I hammer and chisel discovered it takes very little circulation blockage to significantly raise fan speed (measured stroboscopic-ally). A wire surface (radius) presented to the air-flow results in a surprisingly high disproportionate decrease in airflow disruption - on the order of almost 200 RPM! This is significant to no small measure.
The heat-sinking is accomplished with salvaged 1-1/2" X 3" sections of TO-3 black anodized material, plus a number of modified individual TO247 heat sinks. They are going to be applied using thermal adhesive. Some rough calculations reveal a @ 215% increase in BTU shedding (using a 120 MM high capacity fan). I have heard of only one failure of the Megawatt unit and that was jim-in-denver. Cause is unknown but the unit's application to many hundreds of amp hour capacity AGM batteries cannot be discounted.
Alas, finding dual pickup dual readout 12-volt panel meter and thermocouples, came late in the game. But the unit is bound for unsupervised operation so an IR scan shakedown will have to suffice.
One last thing needs to be done, which will require a minor tear-down:
A pushbutton reset 15-amp breaker needs to be installed in the rear panel and I do not have one. If the shakedown reports a 10-amp breaker will suffice, then so be it. A flashing 5 MM LED adjacent to the breaker will announce a fault. It's the inrush current that is an unknown.
Two-stage charging presents a challenge to engineer when flexible voltage plus flexible time is involved. Couple this to where I am doing all this creates the challenge. One-handed makes it an eye-roller.
The heat-sinking is accomplished with salvaged 1-1/2" X 3" sections of TO-3 black anodized material, plus a number of modified individual TO247 heat sinks. They are going to be applied using thermal adhesive. Some rough calculations reveal a @ 215% increase in BTU shedding (using a 120 MM high capacity fan). I have heard of only one failure of the Megawatt unit and that was jim-in-denver. Cause is unknown but the unit's application to many hundreds of amp hour capacity AGM batteries cannot be discounted.
Alas, finding dual pickup dual readout 12-volt panel meter and thermocouples, came late in the game. But the unit is bound for unsupervised operation so an IR scan shakedown will have to suffice.
One last thing needs to be done, which will require a minor tear-down:
A pushbutton reset 15-amp breaker needs to be installed in the rear panel and I do not have one. If the shakedown reports a 10-amp breaker will suffice, then so be it. A flashing 5 MM LED adjacent to the breaker will announce a fault. It's the inrush current that is an unknown.
Two-stage charging presents a challenge to engineer when flexible voltage plus flexible time is involved. Couple this to where I am doing all this creates the challenge. One-handed makes it an eye-roller.
