Mars Electric LLC Axial Flux Motor

The design is similar to an etek or clone.

Looking at the drawing, it appears that the gearbox can be removed and the faceplate with bearing-boss can be retained. So, it might merely be a matter of getting shafts fabbed.
 

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What about retaining the gearbox? This would be great for a crank driven setup or with a minimal reduction from that output to the rear wheel. Just add a sprocket or freewheel and go.

Matt
 
Matt you are thinking like I am... there is value (perhaps) in that 5/1 gearbox. We have to get an idea of the quality of it however. Might make sense for two versions of this motor. I am looking forward to Jeremy's more detailed analysis after (hopefully) he gets a bit more data on the motor.

... I think I am like a few members here, so many interesting projects... that you get overwhelmed except for our "day jobs" most of the time. I started looking at how to make a 5 Kw eddy current motor dyno this morning...
 
TD they are helical from the photo I received last night. It was the same photo posted by the OP but he "Photoshopped" out the output end of the shaft with the helical gear.
 
Not only did Draper photoshop out the helical gear on the shaft, he also edited the drawing to remove the Mars Electric LLC information. John Fiorenza has confirmed that this is indeed his motor and has sent me the full drawing. Bigmoose has also got some photos and drawings which he's kindly emailed to me. Draper was obviously intent on deceit right from the start, as the blurry dyno plot for 36V he posted was also a Mars plot; John has just sent me a copy of it, too.

I can't really see a problem with posting the stuff that John has sent me, as I'm sure that he would welcome any sales that might arise. First of all, here's the full drawing without Randy Draper's edited information:
ME0601010001 Sheet 1.jpg

The dyno plot at 36V has already been posted, but here's a drawing of a 12V nominal, 3000 rpm, 500 watt motor that John has in stock. This motor is OK for 50 amps continuous:


John also has some of the longer, 36V motors in stock, these are OK for 13 amps continuous, so a bit over 450 watts continuous.

There are two stator options that he has available, 25mm thick and 45mm thick. He's happy to get them wound for whatever we want.

The 12V short stack (25mm stator) motor looks interesting as it is. If it would rev at 12,000 rpm (which seems possible) then, as it will take 50A continuous it would be able to deliver about 2.4kW continuous on 48V. My guess is that it might deliver twice this for short periods of time.

Even better might be the 45mm stack stator, wound for a Kv of around 125 or so. I have an Autocad drawing of the motor, but my old version won't open it (I'm still running Autocad 2000.....). If anyone has a newer version and want to convert the dwg file into a dxf that would be useful.

Jeremy
 
recumpence said:
Looks great to me.

So, this seems to be a fantastic option for the sub 1kw arena.

What about 2-3kw? It is merely a KV thing keeping the power lower?

Just curious. I am unfamiliar with this motor style and its performance characteristics.

Matt
Click to expand...

Matt,

The 12V nominal, 50A continuous, 250Kv motor looks like it will deliver 1.2kW with ease on 24V at 6000rpm no load and would probably manage double that if it's OK for 48V and 12,000rpm. I think one wound for a Kv of around half this would be pretty nice. Looking at the design I think it would probably run pretty well with a modded XieChang type controller.

Jeremy
 
Hey, that was mighty quick work, Thud! Many thanks.

I'm still amazed that I can hit send here on an email, the file can whizz across a few thousand miles to you, you can load it, convert it and post it to the forum before I've finished my cup of tea...................

Jeremy
 
Glad to oblige,
It is an amazing world....isn't it.
compound the amazment by all this development has happend in the last 100 years.
mind boggling. :mrgreen:

My father was a child when their dariy farm was the 1st in the area to get "electricity" in the 30's (it was in the barn to run the milkers LOL) they rode in a horse drawn buggy to church untill he was 5 years old. From that to supersonic trans-atlantic flight in his lifetime. Quite humbling.
 
Thud said:
Glad to oblige,
It is an amazing world....isn't it.
compound the amazment by all this development has happend in the last 100 years.
mind boggling. :mrgreen:

My father was a child when their dariy farm was the 1st in the area to get "electricity" in the 30's (it was in the barn to run the milkers LOL) they rode in a horse drawn buggy to church untill he was 5 years old. From that to supersonic trans-atlantic flight in his lifetime. Quite humbling.
Click to expand...

I went to school on a steam train until I was around 10 or 11, when they started introducing diesel locos. My uncles farm still ran without electricity when I was a lad, light came from oil lamps and power for farm machinery was either belt driven by a big stationary engine, with a 6ft diameter flywheel you hand spun to start or by belts taken off the tractor PTO.

I've changed the title of this thread, as it doesn't seem proper to give Randy Draper any connection to this motor.

Jeremy
 
My great grandmother was born in 1896, died in 2006 right after her 110th birthday. She saw such a huge change in technology in her day. From no electricity or cars to fancy cars and the internet!

Amazing is damn right.
 
I'll tell y'all whats amazing. This bunch of people that make up this forum, AND the Admins.

I don't have a lot of knowledge about all this stuff, and, am forgetting a lot I DID know, but, I have never been talked down to, for some of the stuff I post here.

I am just tickled to be allowed to participate on this forum. What a swell bunch of folks. 8) 8) 8) 8) 8) 8)
 
If we were to get some motors wound, maybe as a group buy, what sort of Kv would people be looking for? Or would we be better sticking with an off-the-shelf wind that's available now?

My guess, based on the 12V, 50A continuous, 3000rpm version of this motor is that we might be able to use it as-is, rather than have a custom wind. It all hinges on how strong the rotor is and what its safe maximum rpm is. The rotor diameter is 102mm across the outside of the magnets (85mm diameter at the centre of the magnets), the magnets measure 17mm radially and are 4.2mm thick, so will weigh around 8g (estimated). At 12,000rpm they will be trying to fly off the rotor disc with a force of about 537N (around 121 lbf). They are retained by adhesive plus a machined lip on the rotor disc. This lip is 2mm thick radially and 1.6mm high. Assuming that the rotor disc is made from mild steel of around 300N/mm² shear strength, that the magnets will try to shear this lip away and that the adhesive adds no strength, then the force needed to shear a 17mm section of this lip away is around 10kN, so it looks very much as if there is plenty of reserve strength in the rotor.

The rotor speed limit is going to be determined by the maximum commutation frequency of the controller or the bearing rpm limit, not the strength of the rotor, although I think that increasing the rotor integrity by adding additional high temperature epoxy resin between the magnets might be a good idea, as would dynamic balancing of the rotor disc.

The stator has 18 slots and there are 12 magnets, so this is a 6 pole pair motor. At 12,000 rpm the commutation frequency would be 1200 Hz, which is within the known capability for the XieChang ("Infineon") controllers, I think. I believe that it may well be possible to increase the rpm further. At 18,000 rpm (probably close to the realistic bearing limit with greased sealed bearings) the magnet force will only be just over 10% of the shear stress limit of the rotor retaining lip, so the voltage might be able to be increased to 72V. My guess is that this little motor might be a bit noisy at 18,000rpm, mind.

So, it looks, as least on paper, as if the 12V, 50A motor could be run at 48V, 50A continuous. This would deliver around 2.4kW continuous, with probably double that for short periods. Sounds like a reasonable starting point to me.

Jeremy
 
johnrobholmes said:
Around 65kv would be nice for a single stage reduction motor.
Click to expand...

Winding for a Kv of about 62.5 would decrease the continuous current capability to around 25A (assuming that I²R heating is the limiting factor). The no-load rpm on 48V would be around 3000 and the max continuous power at this voltage would be around 1,200 watts, which is probably a reasonable figure. Peak power may well be double this, as I believe that the motor ratings are true commercial continuous ones, not mythical Chinese numbers!

Jeremy
 
If the previous extrapolations are close, the 125ish Kv looks quite apealing.

I realy think for a every day "bicycle" application going past 66v is detrimantal.
Now for a larger scale outlaw/motorcycle type performance (all mine really)its a non issue.

Jeremy, Can you determine where the point of diminishing returns are for this motor regarding rpm/iron losses with your current data set?

Tool Man2 confirmed my data with the turnigy 80mm motors, There is a nasty drop in efficancy when you cross the 9k rpm threshhold.

Given Axial flux motors are notoriusly constrained with regard to sheading heat (as is out-runner topology) we need to be mindful of efficancys. Although this single rotor design may be better in that respect.

I have no issue with optomisng a wind for optimal power density & adding a reduction to enjoy the bounty.
But that is a different application than a single reduction for a bicycle that would allow a realistic pedal cadence at leagal speeds.
 
Hey Guys,

Josh K here.

We got a couple of these motors, from John Fiorenza a couple years back, as we were designing an alternative to an RC motor.
Seemed to be a cost effective system, motors held up well. Much better than the Perm 080's from Germany, another John Fiorenza
design. Not that I don't like the Perm 080, I thought it was the perfect 750 watt motor for a while, but wrecked a few in testing...

We have used them as mid drive systems, matched em up with a cyclone reduction drive on one, and ran the power through the
bicycle drive train.

Eventually, we went back to the large Astro flight motors, with special helical reductions, as they were smaller, and lighter.
We were trying to stay in the 750 watt area.

Personaly, I like this little motor from Mars, and would like to see what it can do. We understood it as a 24 volt workhorse used
to scrub floors for hours on end. We have been continuously impressed from the Big E tek motors, that are kind of the big brother
of this floor scrubber motor. As far as abuse goes, I continually pump 50 volts through the E tek, at 500 amps, and realign my back
with break neck acceleration... So, I imagine that this motor could take, Say...36 volts, at about 80 amps, all day. Running that
through the bicycle drivetrain, it could become a monster E bike motor, with nice staying power.

I still have a few of these, one with the original gear box, one with the cyclone drive reduction, and one without a reduction.
Maybe I can mount one up on my bench testing system

It was a couple of years ago, but I seem to remember that the motor was kind of grumbly, noise wise, when run on a Phoenix 85.
But I wonder if it could be tuned to make it work better or something...

Josh K.
 
Nice! That would be a nice strong motor to fit between the cranks if your conjecture is correct Josh. Has anybody found the floor scrubber that these go on? I will be keeping an eye out on CL etc... to see if any broken ones pop up.

This I turning into an excellent thread, AND Jeremy is back!! I was thinking somewhere around 65KV would be ideal as well. Are the axial flux motors easier or harder to put sensors on?
 
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