2000W MAC lawnmower motor

[drewjet]

Multiple pics plus size and weight too. That would be great! Thanks.

[flathill]

Multiple pics plus size and weight too. That would be great! Thanks.

Started a new thread for the Ariens motor:
viewtopic.php?f=30&t=41190

[neptronix]

Any updates on the MAC motor

I should be settled in a new place and get back to eBike building by around July 10th.

[magudaman]

Well I got my motor on the bike and running late tonight. I will try some riding tests tomorrow evening.

It was a damn struggle getting my motor fully modified for my use. One delay or problem after another.

First modification was upgrading the 14GA wire to 8GA silicone stuff. This actually went pretty smooth. I was due to go to the shop that week to do the machining but the day I was scheduled the local train system (BART) went down for the entire day causing all kinds of traffic havoc in the area. Then the week I was set to go they screwed up my time slot and scheduled it on the wrong day GRRRRRRR So finally I got out to the shop and knocked the mount plate out and ended up with this:





The weight was brought down to about 1.1lbs so I saved .9lbs It also turns out I knocked out two of the screws that were actually needed and save two that were not Luckily there is just about 3/4 of a hole left and still holds those two bolts.

I brought that home and then found out I did need to modify the shaft some. It needed shortened, keyway extended, and shoulder to be brought back. I had all kind of hell on the lathe for some reason. The stinking ring actually came out of the chuck (really hard to hold) and actually hit the ground, luckily after first landing on a thick rubber mat. I think this did end up tweaking the shaft a little tiny bit (was out of true to begin with though), hopefully this doesn't cause problems with my belt drive.

I had forgot to do the holes in the plastic case with mill so I tried when I got home making it an ugly mess that will be fixed soon with some new little filter covers.

Sorry for all the bitching, I'm done.

I did decipher the hall wire colors today finding that orange is ground and yellow is positive, then I started my mix and match of phase wires and hall wires. I ended up with sets (CW,CCW) of combinations (total of 4) that both seem to work . The one set scares me though because after a couple fast twists and regen slow downs it got stuck spinning no faster than maybe 1/8 speed, not sure what happened controller wise or if something else. After a testing another combination and coming back to that one it seemed to be fine.

The set I settled on at 51.15V does 3.3 amps at full throttle with 3670RPM with a kelly controller

So I will finish up the wiring tomorrow and do my first ride. I'll have to read over this mind pour out tomorrow and clean it up

[magudaman]

Well I got out for my first test rides!

I first finished up all my connection and made it look pretty:



Got it all mounted and took it for a spin.

Here is a little video showing how loud/quiet it is (quieter than my BMC):


Sorry for the crappy quality normally I do better

The specs from my short ride look like I will require active cooling:

4.52mi

2.932ah @ 52v

148wh

Amps max 81.3

13 minutes and 21s

Average speed 20.3mph

Internal air temp (no fan of course, just holes) max: 61.2c

Coil temp Max: 82.4c

Hmmm I think if I calculated it right I did around a 700w average through the length of ride and around ~3900w peak (voltage sag added in)

I think that aluminum body on the BMC unit and aluminum rear case really help the motor. With that said I looked up my old emails with BMC and found that my BMC motor with fins and all was rated at a continuous 1500w. So I wouldn't expect 2kw to work out here, of course with out modification

[neptronix]

Hm! looks like it goes pretty good, of course it is always hard to tell from videos.

Do you plan on doing some further tests?

[magudaman]

Well did some additional testing today and unfortunately I don't think this motor has as much capability as old one. I'll have to bolt on my BMC unit and do a direct contrast to be sure.

So I got my fan mounted today and put some fine screen over all the holes to keep debris out. My ambient was 23C or so according to the motor starting temps. I did my ride and the first peak stop my motor was at 61c air temp and 87c coil. I rode on and up to the first little peak, at 45wh/mi and my coil was at 75c air temp, and 104c coil temp. I let things cool down some to around 80c on the coils and rode on toward the next peak. I was around 49wh/mi and my coils were too hot! Air temp of 88c and 124c on the coil. Even with the coil at 80c you could not touch the metal plate next to the shaft for more than a second or two. But the steel plate was not hot at all out near the edges.

Ride specs:

10.19mi 8.18ah
397wh 39wh/mi
92 amps peak
~33 minutes ride time

So these are not good results. The BMC was geared for more speed and has similar efficiency yet the temps were not near these. My guess is all that aluminum on the BMC sucks a ton of heat out of the laminations and internal air. For example mount plate on the BMC is connected directly to that aluminum core that has the lamination pressed onto. This moves the heat directly from the lamination on to that mount plate which is covered in fins. My air flow could be a bit lower on the MAC than it was in the past due to the screen material but I can feel it moving air. The fan is the same.

[neptronix]

Ah, that's not what i wanted to hear.
You know why i think the 1500-2000w BMC puts out less heat, really? higher KV.

Seems that the faster you can spin a little motor like this, the better. So it would probably perform similarly as the BMC if you put it on 60 or 72v, then geared it down a bit further.

Are you able to do that?

[magudaman]

Yah tell me about I'm skeptical that the kv does that much. I think the superkids rpms are wrong or they have a different wind. Mine spins at ~4300rpm @ 52v. No way to bump the voltage on my setup, nor really gear down anymore. I think the Mac is goin on my dh comp and the bmc back on the Motoped. I might try switching the rotors since the bmc has had a hard life and maybe have had it magnets heated a little hot in the past.

[torqueon]

thanks

[neptronix]

So how many of you dozen people are still interested in this motor?

I'd say this experiment is a fail.

[torqueon]

If the MAC motors are priced cheap, and someone could duplicate the heat path that the BMC motor has, perhaps it could work.
However that's probably a tall order even for guys that have machining ability and a shop.

So it's back to the superkids store at $400.00 a clip !!

The work done here in this thread is much appreciated

Thanks again

[TylerDurden]

I'm wondering how the no-load current on the older motor compares to the new one... any chance the new motor was tested with a false hall combo?

[flathill]

So how many of you dozen people are still interested in this motor?

I'd say this experiment is a fail.

Giving up that easy? When are you going to have your motor running? At least remove the stupid (plastic?) cover

[neptronix]

So how many of you dozen people are still interested in this motor?

I'd say this experiment is a fail.

Giving up that easy? When are you going to have your motor running? At least remove the stupid (plastic?) cover

I agree with your point, flathill. I am giving up too easy.
I am in the middle of moving to Utah right now, so i haven't been building anything, or even doing any eBike riding lately since everything is packed up. Again... i'm sorry for the cliffhanger, guys.

I think it's important to do science(tm) here, but so far:

+ The more expensive BMC appears to outperform it.
+ This motor looks like it may be just slightly more powerful than the MAC hub motor that i already have.

So as far as my expectations go, i guess they do not match what i was thinking.

I will do some testing myself on it soon, it's just that it's not looking all that great thus far.
The advantage is that this motor is going to cost less than half of what they are asking for the BMC.

[John in CR]

I think the best comparison between the motors would be no load current, or if they're wound to different Kv's, then no load watts at the same rpm. A difference indicates a difference in efficiency.

[magudaman]

I'll get to it and post up the numbers here in the next day or two.

[torqueon]

The one thing that keeps coming to mind is that motor delivered to neptronics, looks different, than the one's originally advertised on the sites, that he had discovered. The sites show finned mounting plates and cover. The motors delivered, have flat steel mounting plate and no fins. Magudaman mentioned that the BMC stator is pressed on to a aluminium hub. Is the MAC hub aluminiun or steel, the pics on the MAC look like steel.

From what I know this could make a huge difference

[magudaman]

I think the best comparison between the motors would be no load current, or if they're wound to different Kv's, then no load watts at the same rpm. A difference indicates a difference in efficiency.

Alrighty:

MAC motor @ 53v:
3693RPM 4.05 Amps

BMC Motor @ 52.8v
4470 RPM 4.4 Amps
Reduced speed to 3650RPM 3.65 amps @ 52.6v

My bearings on the BMC could be a bit more worn and doesn't have a sealed bearing on the rear of the shaft (one sealed and one metal shield) where as the MAC has two nice new sealed bearings. When I did my hall configuration I didn't see any difference between no load amps on the two configurations that spun the motor in the direction I needed.

[Miles]

BMC Motor @ 52.8v
4470 RPM 4.4 Amps
Reduced speed to 3650RPM 3.65 amps @ 52.6v

42.6V ?

[magudaman]

No 16s lifepo4, measured 52.6v. What made you think otherwise?

EDIT: Ah that 105kv from superkids! Yah I swear they either have a completely different wind (which I doubt) or they just have the wrong numbers.

[magudaman]

So I didn't have time earlier to post but it seems the efficiencies are similar. I still believe that the amount of heat being removed by the BMC's aluminum fins and aluminum case are a huge contributing factor to the internal motor temperature. I hope to get the BMC mounted again tomorrow, do that same ride with the thermal probes mounted and see what temps I am hitting. I used to run the BMC at 200a+ battery peaks and that what I believe led me to have those magnets separate from the rotor, now were at no more that 80 or 90 amps.

[TylerDurden]

No 16s lifepo4, measured 52.6v. What made you think otherwise?

IIRC, kV is constant...

So, isn't lowering the speed with the throttle effectively lowering the motor input voltage?

4470rpm / 52.6V = ~85Kv

3650rpm / 85kv = 42.9V

[Miles]

Sorry for the confusion....

Tyler,

That's what I half-thought in my half-asleep state.

The 3.65 amps is battery side, though - so you take the battery side voltage.

[TylerDurden]

Ja, that makes sense.

No difference in draw with two different hall combos is still a puzzle to me.