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MCI 102-C3 coach to RV - Engine Bay

Satan's_Minion said:
That condenser motor is MAYBE 1-1.5kW so it is not going to be able spin any of those big blades very fast. Also you need to understand the air side operating point of the cores you are using to pick a good fan for it and know how much power you will need to spin it.

New bus applications transit to coach with electric fan use between 4-8 kW of electric fan power with much more efficient cooler technology but different heat rejection requirements. Factory systems are designed to run at 100% power continuously though, so a home built system and operator could likely get by with less.​
Tis my reason for ordering a single fan to test with. Optical tach and clamp meter are on hand. I have a big roll of window screen to frame up and set in front of the fan to simulate radiator core resistance. It's not exact, but it'll give me an idea of what to expect. If it's a reasonable success, I have a line on more condenser motors to make a total of four. 8 blades at a 22" diameter might be too much. I'll try dropping it to 4 blades and 20" if needed to see what happens and report back. Probably a couple more weeks before the fan shows up.


Adding some links so I have a bundle to come back to. Ol' laptop don't like when I run 30+ tabs for a week lol.
https://www.dartcontrols.com/product...pwm-drive-60a/
https://www.dartcontrols.com/app/upl...nual-3276F.pdf
https://www.omega.com/temperature/pdf/TH-44000-NPT.pdf
https://www.omega.com/temperature/Z/pdf/z256-257.pdf
 
Kinda cool fan assembly. The parts are manufactured by Multi Wing. Its plenty light. I still have the OE condenser fan to compare weight to.

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Even more so. The bushing set screw sits on the key. Gonna give it a whirl. These things hold up to hovercraft, right?

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87manche said,

does it need to be balanced?

I send you my prop balancing rig. You'd probably have to make an adapter though for the hub, and I'm not sure how accurately that could be done without a machine shop and some effort.
 
87manche said:
does it need to be balanced?

I send you my prop balancing rig. You'd probably have to make an adapter though for the hub, and I'm not sure how accurately that could be done without a machine shop and some effort.​
I'll find out. I have to grab some key stock Monday and get the motor bearings replaced - whenever I find the rest of my tools. Might do the cheap blade balancer if I have to.
 
My digital scale max is 5 lbs. so I can't weigh the fans, but just by holding the two, the OE fan is noticeably heavier. I'll see how that compares to the larger diameter of the hovercraft fan.

Pulled the back off the motor and it had a couple blobs of silicone in the bearing pocket. I dont think that's factory. There was probably a spring washer in there, just like the front. McMaster Carr should have suitable replacement washers. I suppose o-rings would work in a pinch. Usable shape otherwise. Some pitting on the bars that will do for now. I'll either have to locate my bearing splitters or buy some more. Rear bearing requires a splitter and the front has room to hook it with a gear puller.

Edit: For fun, I wonder if I could use the toothed ring as a reluctor wheel on each motor just to keep an eye on RPM from the driver's seat. Just a thought.

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The fans were sitting there, and so was my scale. Thought, what the hey, I'll try it. Hoverhawk said this fan was 5 pounds and I assumed that was being conservative. 3lbs. 7.3oz. OE fan hit 4lbs. 1.4oz. Now we know. The only steel on the Hoverhawk fan is the hardware and the center bushing.

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CarterKaft said,
JNHEscher said:
Edit: For fun, I wonder if I could use the toothed ring as a reluctor wheel on each motor just to keep an eye on RPM from the driver's seat. Just a thought.​
I may have dreamed it but I think I remember seeing a fairly simple circuit at one point to measure rpm of a DC motor from the commutator noise.

edit: Back EMF I think is the term.
https://www.precisionmicrodrives.com...from-back-emf/
 
CarterKaft said:
I may have dreamed it but I think I remember seeing a fairly simple circuit at one point to measure rpm of a DC motor from the commutator noise.

edit: Back EMF I think is the term.
https://www.precisionmicrodrives.com...from-back-emf/​
That's the stuff. I'll look into it more. I was thinking a VRS reading the ring, but am not sure if the motor magnetic field would mess with the sensor strength.
 
Satan's_Minion said,

I would not be worried about the weight so much as the drastic difference in blade pitch. Going to have trouble spinning it slow enough to not overload that motor.
JNHEscher said:
The fans were sitting there, and so was my scale. Thought, what the hey, I'll try it. Hoverhawk said this fan was 5 pounds and I assumed that was being conservative. 3lbs. 7.3oz. OE fan hit 4lbs. 1.4oz. Now we know. The only steel on the Hoverhawk fan is the hardware and the center bushing.​
 
Satan's_Minion said:
I would not be worried about the weight so much as the drastic difference in blade pitch. Going to have trouble spinning it slow enough to not overload that motor.​
I agree. I ordered the steepest pitch per recommendation and to see of the motor would turn it. The blades can be ordered individually at whichever pitch you want between 25 and 50 degrees in 5 degree increments. If I had chosen the pitch without asking for suggestions, it would have been 35 degrees.
Edit: Read this again and see that you were talking about the RPM and motor load. I'll be operating each motor with its own PWM power supply to keep everything in check. The controllers have pots to modify maximum and minimum values.

There's another blizzard on the way, so I'm boarding the bus back up today. Bought another bearing splitter yesterday so that I can get to freshening up the motor and get testing underway.
 
Also cleaned out the bearing pockets on the condenser fan motor so I could measure for bearings. Nachi wins. Welded up more battery rails, too.

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The axial preload of the ball bearings is a critical feature in a fan motor FYI. You will want to find a similar spring for it.


Did multiwing give you a curve for the fan blade? I believe they have a calculator on their site also.


Example with made up numbers:

If your motor is wound to spin at 3k rpm and the fan requires 1.5 kW in application to spin at 2k rpm you are going to be trying to run the motor near capacity with reduced PWM duty cycle. The current you would see during each PWM on time will be greater than is present when the motor is running full speed/load. So as I said you could be overloading the motor while its cooling airflow is reduced with less rpm.

How much of this it will put up with is the unknown you are banking on.

If you keep slowing the blade down eventually the motor will be able to spin it safely as the load is cubic with rpm. But your performance at that point will not be good if you are giving 50% pwm duty cycle to get there.
 
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Satan's_Minion said:
The axial preload of the ball bearings is a critical feature in a fan motor FYI. You will want to find a similar spring for it.


Did multiwing give you a curve for the fan blade? I believe they have a calculator on their site also.


Example with made up numbers:

If your motor is wound to spin at 3k rpm and the fan requires 1.5 kW in application to spin at 2k rpm you are going to be trying to run the motor near capacity with reduced PWM duty cycle. The current you would see during each PWM on time will be greater than is present when the motor is running full speed/load. So as I said you could be overloading the motor while its cooling airflow is reduced with less rpm.

How much of this it will put up with is the unknown you are banking on.

If you keep slowing the blade down eventually the motor will be able to spin it safely as the load is cubic with rpm. But your performance at that point will not be good if you are giving 50% pwm duty cycle to get there.
Click to expand...

I haven't received or seen any charts for these fans, yet. Finding and fitting up a fan that featured adjustable variables to work with what I have on hand was the first step.

Calculations for this setup are going to become necessary as I feel that the cheap instrumentation I'll be using to take measurements with are nowhere near accurate enough. To be determined.
 
A fellow bus owner friend spotted another bus owner looking for some radiators. He let them know that I still have mine that I pulled out. Figured I'd better get my arse out there to measure their volume like I've been wanting to. The OE rads hold 4.01 gallons each. I'll measure one of the Micon cores. I was wanting to make a comparison so that there won't be any unknowns.

Edit: Pulled one of the Micon cores out to measure while I had the scale out. 0.212 gallons each, once you shake the air out.

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Been trying get the OE radiators sold which motivated me to get back to reassembling the test fan assembly. Wire wheeled, greased, new wave washers and Nachi bearings in. Smooth roller, now. Waiting for the batteries to top off before I hook up.

I sure thought my clamp meter had a peak/starting current hold, but no such luck. I'll do my best to capture the highest numbers by eye. Starting current isn't a big deal because the PWM controllers have an adjustable soft start. I just want to know.

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Satan's_Minion said,

I wouldn't bother with that, a "cheap" clamp meter will not report the correct values even if it has a peak function.

Theoretical values for a PM motor would be in the 6-7 times running current. But in the system the harness and power source voltage drop will decrease that.

If you want to know you will probably have to stall the motor and then read that value. Don't do it for more than a few seconds as it will be hard on everything. Also if you have a low ohm meter you can measure the resistance to calculate it but almost no one has one of those.
JNHEscher said:
I sure thought my clamp meter had a peak/starting current hold, but no such luck. I'll do my best to capture the highest numbers by eye. Starting current isn't a big deal because the PWM controllers have an adjustable soft start. I just want to know.​
 
Satan's_Minion said:
I wouldn't bother with that, a "cheap" clamp meter will not report the correct values even if it has a peak function.

Theoretical values for a PM motor would be in the 6-7 times running current. But in the system the harness and power source voltage drop will decrease that.

If you want to know you will probably have to stall the motor and then read that value. Don't do it for more than a few seconds as it will be hard on everything. Also if you have a low ohm meter you can measure the resistance to calculate it but almost no one has one of those.​
I know, but it's about all I have. Should be able to stall the motor with the fan on as leverage, but that might be a fight I shouldn't pick. Gonna go see if the first battery charged at all. If not, I guess I'll hook up the lithium pair. I really want to see if this will work or if I need to go back to pondering the hydraulic setup.
 
87manche said,
JNHEscher said:
Been trying get the OE radiators sold which motivated me to get back to reassembling the test fan assembly. Wire wheeled, greased, new wave washers and Nachi bearings in. Smooth roller, now. Waiting for the batteries to top off before I hook up.

I sure thought my clamp meter had a peak/starting current hold, but no such luck. I'll do my best to capture the highest numbers by eye. Starting current isn't a big deal because the PWM controllers have an adjustable soft start. I just want to know.​
aim video camera at meter.

dicks with motor.

review video for peak numbers.
 
87manche said:
aim video camera at meter.

dicks with motor.

review video for peak numbers.​
I do feel stupid for not thinking of that. Tonight or tomorrow. The first battery finally charged. Second may have to run overnight as well. Fresh batteries in my meter and tach.

I've been looking all over for the end cap diagram for the Micon folded cores while waiting on the batteries, but can't find it anywhere. I'm about ready to mock the cores up again and draw the end tanks in Fusion360.
 
bigun said:
On my phone; shouldn't all that information be on the motor plaate?​
Yeah. I've posted it before. 55 amps, 2,900 RPM. I'm not really sure if the amps is locked or running with full load. I'm going to taking note of the current with and without a load.
 
Still charging. Bet the first battery will be dead by the time the second one is done.

Peeled more junk out of the squirrel cage bay. Getting it down to bare bones so I can decide what to replace and/or modify. As suspected, flaky rust where all that sound deadener and fiberglass was matted over top. I would like to get the CAD file of the radiator core assembly together before chopping up too much.

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87manche said,

have you considered buying one of those 3d scanners?

I mean, now that you're deep into it and it would have been handy from the start.
 
87manche said:
have you considered buying one of those 3d scanners?

I mean, now that you're deep into it and it would have been handy from the start.​
I have thought about this many times over. Last I saw, faro arms were something like a million dollars. I see chatter about scanner apps for iphone. A scanner would seriously help out, but then again, I do have fun drawing parts from scratch by measuring with calipers. There's something about scanner that looks as though you don't get a very personal feel for the objects that you're working on.
 
bdkw1 said,
JNHEscher said:
There's something about scanner that looks as though you don't get a very personal feel for the objects that you're working on.​
True if your sitting in an office somewhere with somebody else doing the scans. Pretty sure your going to get very personal with everything there.

Had an ad for a scanner set-up for a smartphone pop on book of faces. Sent it to My boss, told him for 200$ we could replace our 80K Leica POS. He was not amused
yH5BAEAAAAALAAAAAABAAEAAAIBRAA7
 
bdkw1 said:
Had an ad for a scanner set-up for a smartphone pop on book of faces. Sent it to My boss, told him for 200$ we could replace our 80K Leica POS. He was not amused
yH5BAEAAAAALAAAAAABAAEAAAIBRAA7
That's too funny. Haven't found such an app for android. I'd give one a try though.
 
Ran it. No Load specs and Load specs are as best as I could tell from taking video of my meter. Load rpm was hard as hell to read because the fan was blowing me around so much. It sat on 2500 the most, but I saw it as low as 1900 which would be more likely.

So, holy hell. It turns the fan without flinching, moves a shit load of air, and draws too many amps. I'll take half the props out and try again. I never took a good look at the fan hub the night I was putting it together, but I recall there being other slots in it that may accommodate a 2, 3, 4 ,6 and 8 blade configuration. I should be able to blade swap without taking the hub off the motor.

I'm not holding the fan to test locked current, by they way. My arms would be hamburger with as hard as it kicks. I'd rather not put a strap on the props to hold it either.

Edit: This thing was pushing as much air as the dual squirrel cage on its own (with the engine revved). If I'm still running four of them, I need to tone it down a bunch which should get me back to the stated running current or less. I've seen 24-volt Hummer fans for around $90. Kinda tempted to try one out just because of how much overkill this condenser fan motor and Hoverhawk fan is.

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