Revolt RV-series motor review and comparisons

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ElectricGod   10 MW

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Revolt RV-series motor review and comparisons

Post by ElectricGod » Jun 27 2018 4:01pm

I recently discovered Revolt Motors out of Israel.

I'm really tired of the Alien Power BS and pathetic customer support!!!
I've been using Alien Power for a good while for EV grade outrunners, but my experience with them has been less than wonderful. Getting a reply back is usually 2 or 3 days of waiting and I rarely get a complete answer so I have to ask over and over again to finally get the information I want. Never mind the delays of many days between responses! I'll number my questions 1 to 5 to make them each UBER CLEAR. if I'm lucky, one or two will get a partial answer. Communicating with AP is frustrating on a good day! Then my last order was for a 80100 and 12090. I specifically talked about getting complete motors, hall boards and parts kits. AP outrunners include kits for mounting the motor and propeller. The C80100 kit was completely missing and the 12090 was not even a complete motor...never mind including the kit! I contacted AP for the missing parts. Sever days later I was told they were shipped to me with the motors. Uhhhh NO THEY WEREN'T!!!! I would have noticed!!! So... several more emails later with long delays from AP and finally I was told replacement parts were shipped. A month passes...no parts. GRRRR! I contact AP again and by now they have forgotten all about me so I have to explain multiple times all over again what I was missing. This time I insisted they ship with tracking so I had proof they actually shipped. Weeks pass...no shipping information. I'm thoroughly MAD with AP by now and express it in my email. Finally a week later I get tracking information showing the parts shipped that day. All I can say is WTF is wrong with Alien Power?!!! Obviously they want to piss off their customers! I think I'm thoroughly done with Alien Power ever seeing another dollar of mine! See below for motor quality pictures. This is yet another reason to NOT use Alien Power again.

Thanks to pathetically horrible customer service from AP, I was looking for some place NOT AP to buy motors from and found Revolt. I wanted to interview them to see how they performed. I wanted to see their customer service in action. OMG!!! What a HUGE improvement over Alien Power! I asked them all sorts of questions about random motors of theirs. There were times when it took several tries to get the information I wanted, but they always answered within an hour or 2. Overall, I'd have to say Revolt is helpful, informative, patient and friendly. AND it was another week before I even bought a motor yet!

As a test of Revolt, I bought an RV-100-regular outrunner. Shipping by ship from Israel to the USA took 45 days. China by ship is more like 15-20 days. If you need it faster than that, expect to pay a heavy shipping cost to get it quickly. The motor was $45 by ship or $105 by air. I was not expecting that steep of a price in either case! Alien Power charges $30 to ship the C80100 to me and it takes less than 2 weeks. Shipping from Revolt is prohibitive to say the least! Then how sloooow it is...makes that $45 downright expensive! This is my single biggest complaint about Revolt. Slow shipping and exorbitantly expensive. I've ordered items from Israel before and they did NOT take 45 days to arrive and shipping was not outrageously high. I totally get paying more for shipping over seas, but honestly, this was the MOST EVER I've paid for shipping from any country. I buy from Europe, UK, China, Isreal and the USA pretty regularly. Shipping from Revolt eclipsed everything else by 30-50% more cost.

I figured what better way to get to know Revolt than to buy a random motor that's on sale. If I found the motor was garbage I'd be out $190 and at worst, I'd put it up for sale. I've spent lots more than that over the years on EV stuff that I'll never use so I saw it as a reasonably worth while risk to take if it eliminated sucky Alien Power from my life. Over all, I'd say it was a worthwhile risk and while shipping is exorbitant, the motor quality is MUCH better and customer service is MUCH MUCH better. Good riddance Alien Power!!!

Onto the motor stuff...

This is the exact motor I bought.
http://www.revolt.org.il/sale/rv-100-regular-sale/

.

Complaints about the motor:

1. The phase wires are 12 awg silicon. I wish they were 10 awg silicon, but 12 awg is sufficient.
2. The motor comes with shielded bearings, but this is pretty typical. I've never seen an outrunner come any other way.
3. There's no universal mounting kit or prop adapter. It's not even an option as a separate item to buy.
4. Set screws are used in the bell end caps as small weights for balancing the motor. They are not secured with locktite.

Things I REALLY like:

Most of my comparisons are between the RV-100-regular and the Alien Power C80100. This "low end" Revolt motor is a much better product than the C80100 in many ways.

1. The stator is bigger. The Revolt specs say 80mm. Alien Power does not say, but it's 68mm.
2. Bigger magnets. These magnets look to be about 16mmx50mmx3mm. I believe the C80100 magnets are 11mm wide. Length and thickness look about the same. There's no gaps between the magnets like the C80100 has. This is actually less than optimal. You want gaps between the magnets.
3. Bigger stator teeth. The C80100 has about 6mm gaps between the teeth. The RV-100 has 1mm gaps.
4. The stator is wound with 18 awg wire. The C80100 with 32 awg. The windings are tight and even and the stator teeth are 100% full.
5. The wound stator looks like it's soaked in epoxy.
6. The outer bell shielding is better. I used an allen key. The C80100 grabs steel objects quite strongly. The RV-100 attracts steel, but not as much as a C80100.
7. The C80100 is rated for 7kw which is silly. 68mm stators typically max out at 5kw. My C80100 does a bit less than that. The RV-100 is rated for 2kw continuous and 5kw peak. Bigger magnets, bigger stator, 100% full stator windings...I bet 6500 watts continuous is likely.
8. Same sized shaft (12mm), but this one has 3mm key ways on both ends. Supposedly the shaft to bell union also has a 3mm key in it.
9. The motor is a good bit heavier than a C80100. I won't know for sure until I actually hold both motors in my hands, but I'll give it an extra 2 pounds of mass. That's probably 80% from a larger and fuller stator and bigger magnets.
10. Motor height is very close to the same, but diameter of the armature is a good bit larger on the RV-100.

EDIT:
As will be seen further on in this thread, there is some debate about eddy currents in the magnets and what causes them. These eddy currents are waste heat and reduce motor efficiency. I have found a few articles on the subject of gaps between the magnets helping with this issue, but nothing about electrical conduction between the magnets or the armature back iron. Very LOW ohms resistance between the magnets and armature back iron is extremely common in motors. What I said above about the magnets filling the armature space is actually not optimal or the best design. There really should be gaps between the magnets to reduce eddy current losses in the magnets.

https://www.motioncontroltips.com/motor ... ariations/
https://www.edn.com/design/sensors/4406 ... Principles
https://www.jmag-international.com/cata ... tLoss.html


A few pictures...more will come later when I take the motor apart and use a better camera.

Image

The holes tapped around the perimeter of the bell top and bottom have small set screws in various places for balancing. Alien uses globs of JB weld epoxy between the magnets inside the bell for balancing. This is much better! I think they tap M2 holes around the perimeter and then if needed redril/retap them to M6 if they need to add more weight. 90% of the threaded holes are M3 and only 3 are M6.

Image

This is the motor base. Before I mount the motor to anything, I'll have to pull off the spacer and make a plate so that my mounting screws to the EV frame are further away from the shaft. The M6 screws are just long enough to bottom out in the 12mm deep threaded holes when passing though the spacer. The actual bottom of the motor stands about 1mm longer than the bottom of the motor bell. This is pretty useless as is. Revolt...PLEASE make a motor base we can actually use!!!! See my comments about the C80100.

Image

I'm not sure why it was done this way, but the bell top has 6 8mm holes and 6 15mm holes for air passage, but the bottom only has 8mm holes. Ventilation will be limited here.

Image

Those stators are 100% full of 18awg copper.

Image


Lets look at the C80100 for comparison. I still like this motor a lot, but by comparison to the RV-100-regular (base model shown above)...well it's just not as good.

Much less copper fill per tooth. I'm going to estimate 75% full and it's wound with 32awg strands. The gaps between the teeth is about 6mm.

Image

The stator looks like it's coated in epoxy, but the tiny wire strands are not. They can be easily damaged.

Image

Smallish magnets with large gaps between them. I think they are 11mmx50mmx3mm. The gaps between magnets are important, but they don't need to be this large. 1mm is sufficient. The lack of gaps between the magnets in the RV-100 is actually less optimal than these large gaps.

Image

This is what I do to the AP C80100 to make the stator hold up to the weather...give it a good dose of electrical paint!

Image

I do wish the RV-100 had 4 screw holes in the top like the C80100 does. There's a good chance that people will want to use the motor with a propeller or reinforce the shaft to bell union.

Image

The base of the C80100 can be mounted directly to things which is VERY convenient. The 4 M6 screws mounting the base to the motor are about 40mm apart. The ones for mounting the motor are about 60mm apart. The entire RV motor series needs you to make your own custom motor mount. A universal base that comes with the motor would be brilliant!

Image

Image

Image

I want a kit like this with the RV-100 and there's nothing at all. I did strongly recommend adding something like it to the entire motor lineup from Revolt, but Revolt claimed that people were using their motors in far too many differing ways to make a universal kit. I disagree. They should make it at least as an add-on kit that you buy separately. I sure want one! The factory motor base can't be used IMHO for anything

Image

Conclusions:
My Currie scooter is very strong, accelerates well and it tops out at 45 mph on the C80100. It could go faster if I geared a little closer to 1:1. The motor has plenty of torque to get me to 45 mph and up steep slopes from a dead stop. It's geared at 4.1:1 or 74:18. If I dropped that to 70:18 or 3.9:1, I'm very confident that 50mph would be doable with only a small reduction in torque at the wheel. With the RV-100-regular motor on the Currie, it would be MUCH faster and stronger than it already is. I suspect I'd deliberately turn down the phase amps just to tame the motor. It would literally be too powerful for the 75 pound scooter. This motor can drive a much larger EV without trouble. What's more is this is the weakest model in the RV-100 line-up! I think I'll seriously look at getting an RV-100E soon...just for comparison. I really want a universal kit!!! Otherwise, I'm very pleased with the motor. it's a way better motor than the competing C80100 and this is just the base model RV-100.
Last edited by ElectricGod on Jul 25 2018 2:09pm, edited 10 times in total.
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Re: Revolt RV-series motor review

Post by spinningmagnets » Jun 27 2018 4:52pm

The lack of epoxy on the wire strands is troubling (on the 80-100). When the motor is running, those wire bundles will vibrate, and the insulating wire lacquer will slowly rub off, causing a short.

I had assumed that Alien Power motors were at least slightly better than Turnigy, oh well. Thud has an excellent pictorial on rewinding these large RC outrunner with new wire, and making them a lower kV plus terminated in wye, with inductance being improved, then adding halls do it can be run by an ebike 12 Fet controller....if interested, check the motor section sticky index.

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Re: Revolt RV-series motor review

Post by ElectricGod » Jun 27 2018 5:28pm

spinningmagnets wrote:
Jun 27 2018 4:52pm
The lack of epoxy on the wire strands is troubling (on the 80-100). When the motor is running, those wire bundles will vibrate, and the insulating wire lacquer will slowly rub off, causing a short.

I had assumed that Alien Power motors were at least slightly better than Turnigy, oh well. Thud has an excellent pictorial on rewinding these large RC outrunner with new wire, and making them a lower kV plus terminated in wye, with inductance being improved, then adding halls do it can be run by an ebike 12 Fet controller....if interested, check the motor section sticky index.
I've talked to Thud and read his thread on rewinding these 68mm stators. He told me his best rewind was getting him about 4800 watts at the motor. That's about what I get out of the C80100 from the factory.

I'd buy an AP motor over a Turnigy every day of the year! The Turnigy 80-160kv has a far inferior bearing and shaft set up. The center tube is thinner inside the stator. The prop adapter is part of the motor bell so it's not removable. They both use 32 awg wire and there's no epoxy on the windings. The motor base is screwed on by 5 12mm long M4 screws. I got my 80-160kv new and one of the screws was stripped out. I had zero confidence in the the motor base holding under moderate loads. I retapped them for M5 and used screws that maxed out the threads. The AP C80100 uses four M6 screws that use all the threads. I have lots of confidence that they will hold long term. The 80-160kv motor shaft is 8mm as compared to 12mm on the AP C80100. I'd probably never drive from the 80-160kv shaft...it's just too small and pathetic.

These larger screws were absolutely necessary.

Image

The prop adapter is machined as part of the bell top. This picture was from early on when I was reinforcing the shaft to bell union. It had 2 M4 set screws on the shaft. I replaced them with 6 M5 set screws that each sat on a flat on the shaft.

Image
Last edited by ElectricGod on Jul 25 2018 2:11pm, edited 1 time in total.
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Re: Revolt RV-series motor review and comparisons

Post by ElectricGod » Jun 30 2018 2:55am

A few more pics of the RV-100-regular motor. It took a while and lots of very careful prying in the tiny gap between the bell wall and top, but I finally got it loose just a tiny bit. Then I put my smallest puller in the holes and started slowly pulling. I did get the top off, but it wasn't without some amount of concern. Probably the next time I take it off, it will be a lot easier to remove. The bottom cover only has 8mm holes. My pullers jaws won't fit in them. I'm not sure how I'll get the bottom cover off.

I took out all the screws around the perimeter of the bell and found 2 that had no threads in the holes. The screws were held in with locktite, not threads. I don't have an M3 tap at the moment. The things are so tiny, I snapped off the last of my stock a while back and never bought any more of them. I'll pick some up tomorrow. I've also ordered some longer torx head screws so I can deal with the stripped out holes by going deeper into the metal. The holes are mostly about 8mm deep, but some are only 6mm which is just barely long enough for the 6mm long screws. In this regard, I'm not overly impressed.

The next thing I found is once the bell top was off, there was only 1 key between the shaft and bell top, but both parts have 2 keyways. Ordered more 3mm keys...grrr!

The final detail that was not good is Revolt uses set screws as weights, but don't secure them with locktite. I was able to easily remove all of them. They would have slowly worked out of the threaded holes on their own if I didn't locktite them in place!

All I can say is Revolt does some stuff really well and then they fail completely on others. They seem to have issues with quality control.

So then on to the good stuff...

Now that I have the top removed, I can clearly see that the windings are very nicely done and embedded in epoxy. 12 teeth and 14 magnets...very nice! A C80100 has the same layout, but not the same grade of design.

RV-100-regular. Large magnets and stator teeth. Oh look...needs sealed bearings, but that's pretty typical. No one uses sealed bearing for some dumb reason. The very slight increase in friction added by the seal touching the inner race is negligible compared to the fact that the bearings will never get polluted and fail from dirt and water incursion.

Image

Alien Power C80100. The stator teeth and magnets are much narrower, but the same length. I replaced the bearings with sealed hybrids. It originally came with shielded bearings

Image
Image

Why is there no key in here, but there is on the other side of the shaft?

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There's just no way these are both the same wattage. If the C80100 is 7kw like AP says, then the RV-100 has to be more like 8kw. That too is silly since I know that the C80100 is really only good for about 4800 watts. In that case the RV-100 has to be good for 5500 to 6000 watts. The Rv-100 has a significantly larger diameter stator. The magnets are in fact the same length and thickness. Side by side testing with an allen key, the C80100 has about 1/3 as much magnetic shielding or 3X more magnetic pull on the outside of the bell. Other than the details mentioned above, the Revolt motor is clearly the better motor.

Image
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Next thing to do is make a mounting plate that duplicates this 6 bolt pattern and is a good bit wider so I can mount the motor into 4 elongated slots that are about 40mm apart. While the motor is apart, I'll add halls to it. That will go in my hall thread.

Adding halls to motors: viewtopic.php?f=30&t=84112
Last edited by ElectricGod on Jul 25 2018 2:18pm, edited 3 times in total.
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Re: Revolt RV-series motor review and comparisons

Post by ltu » Jul 01 2018 10:57am

hello electricgod

good report

do you have more about the 12090 outrunner?

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spinningmagnets   100 GW

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Re: Revolt RV-series motor review and comparisons

Post by spinningmagnets » Jul 01 2018 1:48pm

A link to this thread had been added to the motor pictures dis-assembled thread stickey.

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Re: Revolt RV-series motor review and comparisons

Post by madin88 » Jul 02 2018 4:23am

Thanks for your review and the pics.

To be exact the C80xx series don't have a 80mm stator diameter. This number refers to the outside diameter which can be really confusing sometimes when comparing differnt motors among different brands.

It would be best if you could measure the real dimensions of the stator together with other things like:
- phase to phase risistance
- phase to phase inductance
- lamination thickness.

What controller are you using and what's the no-load consumption at rated RPM?
3. Bigger magnets. These magnets look to be about 16mmx50mmx3mm. I believe the C80100 magnets are 11mm wide. Length and thickness look about the same. There's no gaps between the magnets like the C80100 has.
It doesn't mean the performance is better if there is a gap between the magnets or not.
Fact is that more advanced motor designs with surface mounted magnets have a gap between mostly in order to reduce the spinning mass.
It simply is not necessary to glue them side by side because the fields cancelling out in this area. having no gap would not contribute to more torque.

IMO the rotor of the C80 motor looks better designed as there is almost no visible gap between magnets and the back iron, while on the RV100 there is a huge gap. The larger the gap, the lower the field strength.
6. The outer bell shielding is better. I used an allen key. The C80100 grabs steel objects quite strongly. This motor does attract steel, but not as much as a C80100.
If revolt would have used bended magnets to get reid off the gap, it likely would grab steel objects much stronger. From the look, the thickness of the bell looks insufficient.

Yes copper fill looks really good on this motor, but without knowing any numbers of above mentioned measured values it is hard to say if the motor is good or not so..

Recently i built a mid-drive with an outrunner with 80mm dia and 57mm stator. This motor can take 10kw peak (controller at max settings) for quite a long time, and real continuous it is in the range of 5-6kW (temp does not climb above 110°C).
The type of controller (or the settings) are also very important in view of the the power you can get out of that kind of motors.
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Re: Revolt RV-series motor review and comparisons

Post by ElectricGod » Jul 04 2018 1:11am

This is top down view of the stator and armature, there's a paper thin gap between them. You can't get much closer to touching than that! I don't know what you are talking about regarding a "huge gap" except at the left and right ends of the magnets...where it matters the least. I had previously posted that curved magnets are used on the RV-100-pro and -E versions, but not on the base model (RV-100-regular...this motor). This is the low end or base model Revolt motor, NOT the best of their product line.

Image

I pulled out my micrometer. I did say I had never measured the stators...well I was apparently wrong. Live and learn!

C80100 has a 68mm stator and bell diameter is 80mm.
The RV-100-regular has a 80mm stator and a 93mm armature diameter.

C80100 and RV-100 stators side by side. Same length (42mm), but the RV-100 is 25mm larger. I can't see the stators very well in the RV-100 since they are wound, but they appear to be 2X thicker across the wound section than the C80100 stator. The stator lams are the same thickness (.3mm). There's probably 60% more iron in the RV-100 stator than the C80100 stator. The ends of the stator teeth account for probably 20% of that.

Image

I got the bottom off the motor. I used 3 of those 8mm holes in the armature bottom and tapped 10mm threads in them. That gave me a way to grab a hold so I could attach my puller to get it removed and to push the stator out of the armature. I seriously doubt Revolt intended for people to take their motors apart. This was much harder to do than the C80100 which has lots of places for the puller arms to grab onto.

Image

Personally I think this is a nice stator with good winds on it that are embedded in resin.

Image
Image

Bigger magnets produce more reaction to the phases than smaller magnets...so filling the space to maximum ought to mean the motor is stronger as well. You can only produce torque in a motor as strongly as the magnets can push or pull. AKA bigger magnets are better than smaller ones at reating torque. They do have a downside in that they also create more cogging or attraction to the the stator teeth that are not energized. Which is better then? Smaller magnets that cant generate as much torque but are lighter or larger magnets than can react more strongly, but weigh more? The fact that the magnets physically touch is less than optimal. They need a 1mm gap between them to help control eddy currents in the magnets.

Image

I think the shaft is a bit over engineered. There's little chance it can wander around in the bearings. The shaft has circlips on both sides of the bearings. It's not going anywhere. Comparing to the C80100 which has a single circlip, it doesn't wander around either. SO IMHO 4 circlips is probably overkill. The C80100 has 2 shaft bearings at the top of the bell and 1 at the bottom of the bell, plus the skirt bearing. The RV-100 has only 1 top shaft bearing. They obviously didn't make this motor for running a prop so the lack of second top bearing isn't surprising. The bearings are an interference fit on the shaft. They do NOT just slide on. You have to press them into place. Since I had the motor apart, I replaced the factory shielded NSK 6901 bearings with sealed hybrid 6901's. I've also ordered a sealed 6808 skirt bearing which will arrive probably Saturday. They used NSK bearings everywhere which is pretty nice. I just wish they were sealed!

Image

Since i had the end caps off the armature, I drilled and tapped out the perimeter screw holes all the way through with M3 threads. I have 10mm M3 torx head screws coming. There's no more than 10mm for threads so there was no point going longer. In every hole, I gained about 3-5mm of threads.

Next up while the skirt bearing is being shipped, I'll add halls to it. I have no idea how I'll get the hall wires out of the motor. there's no room anywhere to run them. The best idea I have right now is use one of the 6 M6 screw holes for the hall wires. How revolt adds halls to this motor is anybodies guess.
Last edited by ElectricGod on Jul 25 2018 2:30pm, edited 1 time in total.
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Re: Revolt RV-series motor review and comparisons

Post by madin88 » Jul 04 2018 3:01pm

ElectricGod wrote:
Jul 04 2018 1:11am
This is top down view of the stator and armature, there's a paper thin gap between them. You can't get much closer to touching than that! I don't know what you are talking about regarding a "huge gap" except at the left and right ends of the magnets...where it matters the least. I had previously posted that curved magnets are used on the RV-100-pro and -E versions, but not on the base model (RV-100-regular...this motor). This is the low end or base model Revolt motor, NOT the best of their product line.
I was talking about the gap between the magnets and the back iron (the rotor).
The back iron is there to increase (roughly double) the strength of the magnets.
As there is quite a big gap the strength is way lower as it could be, which leads to lower torque and probabaly to earlier saturation.

Whereas a gap between the magnets side by is usually a good thing or a sign of a more advanced design (weight optimizied).

I wonder why you bought the cheapest version of this motor without hall sensors when you can get them installed for a few extra dollars...
Or is there anything wrong with the stock sensors?

The revolt E versions don''t look bad!
- 10kW belt drive with Neumotor 8057: viewtopic.php?f=30&t=91144&start=50#p1377787
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Re: Revolt RV-series motor review and comparisons

Post by ElectricGod » Jul 05 2018 10:42am

Why I bought this motor was discussed by me in the very first post and several times...to interview Revolt. Looking back, I can't find where I talked about differences in the magnets in the RV-100 series. Maybe I remembered that wrong.

I'm sure you mean some gap somewhere. I consider myself to be pretty observant since I test software for a living, but I'm flat out missing this gap you are referring to. The gap between stator teeth is about 1mm, but that's not what you are talking about. The gap between the ends of the stator teeth and the magnets is about the thickness of a sheet of paper in the middle of the arc of the stator teeth. Of course a flat surface next to a curved surface is not going to be as close at the edges of the flat surface. All I can say is I don't see this gap you are talking about.

Image
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Re: Revolt RV-series motor review and comparisons

Post by spinningmagnets » Jul 05 2018 11:22am

The faces of the rotor teeth are curved, and the back-iron can is also curved. Many believe there is a small benefit to using curved magnets instead of flat pieces. Then tightening up the air-gap...

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Re: Revolt RV-series motor review and comparisons

Post by ElectricGod » Jul 05 2018 1:00pm

spinningmagnets wrote:
Jul 05 2018 11:22am
The faces of the rotor teeth are curved, and the back-iron can is also curved. Many believe there is a small benefit to using curved magnets instead of flat pieces. Then tightening up the air-gap...
I would think that curved magnets would be better than flat magnets since they are the same gap at the edges of the stator teeth as they are in the middle of a tooth. Whether this difference is slightly better or "blow my mind" way better, is something I can't really say. I'd need 2 identical motors, one with flat magnets and one with curved magnets and see if it matters very much or not. If the difference is very slight, then I can completely understand why motor manufacturers don't bother with the extra expense of curved magnets. I'm sure that with the larger gap at the edges of the magnets that there is less magnetic force there due to the gap, but the magnetic field in the phases is going to be the strongest at the center of the tooth anyway. IE: That gap due to NOT having curved magnets is probably fairly irrelevant.

In the RV-100E, there's several changes over the RV-100-regular. Curved magnets and N45 instead of N40 magnets, better back iron for improved shielding. I don't know what else is improved that would effect the motors efficiency or torque. Will those things make enough difference to warrant the extra cost? The "regular" motor is hampered by less than stellar ventilation out the bottom of the motor. The Pro and E versions have large openings and a built in radial fan. Revolt claims the Pro and E are more powerful motors. I don't think the stators are larger or longer. Revolt presents very few details for the "regular" motors on their web site. It's hard to compare specs when they are not listed!

2-5kw for the RV-100-regular
3-6kw for the RV-100-Pro
6-11kw for the RV-100E


Whether those numbers are exaggerations or not is a guess right now, but 2kw continuous vs 6kw continuous out of the same size stator is impressive...if it's real. Honestly though, I already get about 4800 watts max out of a C80100. How could a larger stator with more copper do worse than that? IE: the "regular" motor ought to realistically be about 5kw continuous.
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Re: Revolt RV-series motor review and comparisons

Post by thepronghorn » Jul 05 2018 3:26pm

Like madin88 said, measure the Rm, Kv, and no load losses at two different voltages, and then we will be able to compare these two motors performance wise (inductance would be nice as well for an indicator of the "controllability" of the motor). You have already covered their mechanical design fairly well. One measurement that would also be nice is the stator lamination thickness (careful inspection of the stator photo you posted indicates 0.5mm lams, but the picture quality wasn't high enough to easily count laminations).

Like others have said, some of your electrical design comments need a little clarification.

You mentioned that you liked the 100% magnet coverage, but usually a motor's torque/weight ratio is optimized somewhere closer to 80% coverage. The 80100 motor was designed with the intention of optimizing power/weight for model airplane use. For our applications, weight may be a smaller factor, but optimal magnet coverage still varies from motor to motor and user to user, so it is hard to say that the Revolt motor is definitively better than the 80100 in this category.

Spinningmagnets wasn't quite correct. What madin88 was pointing out is that the flat magnets cover 360/14=26 degrees of the rotor each which results in a maximum gap to their back iron (the rotor steel) of 2.6% of the motor's radius (exact solution is 1-sqrt(1-pi^2/14^2)). For a 80mm diameter motor, this results in a 1mm air (plus some epoxy) gap from the flat magnet to the curved back iron which means the back iron is much less effective at linking the magnet flux since the flux must jump across the 1mm gap.

Thicker stator teeth means less space for wire. This improves peak power capability but decreases continuous power handling. Again, specific motor design parameters are not necessarily good or bad, they are all varied by the motor designer in order to optimize for the motor's performance targets and constraints (speed, torque, power, weight, cost, size, etc.).

Thanks for the motor review. Others have posted varying reviews of Revolt motors in the past, but your in depth analysis is good content.

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Re: Revolt RV-series motor review and comparisons

Post by spinningmagnets » Jul 05 2018 4:48pm

Justin had a long thread a while back where he was developing his ideal small direct drive hubmotor. During that discussion, he compared magnets that touched side-to-side, against magnets that had some gap between them...

Like almost all things concerning motors, there were benefits and drawbacks to each approach. I seem to remember that having a small gap reduced cogging, while only losing a small amount of torque-per-watt.

Of course, I could be wrong, that thread is from quite a while ago...

As far as the curved magnets go...I seem to remember that the curved magnets had only a small benefit. The MXUS turbo series hubmotors tauted their curved magnets and the resulting thinner air-gap, but the consensus at the time was that...it was only worth it if the planned production numbers were high enough that the curved variety were close to the same price as flat.

Narrow magnets (in the shoulder to shoulder axis) can use a thinner and lighter back-iron. Wider magnets would result in fewer poles? per the same diameter motor...which would be good for reducing the electrical switching frequency. That used to be an issue, but I think controllers are available now that handle high Hertz...

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Re: Revolt RV-series motor review and comparisons

Post by ElectricGod » Jul 05 2018 4:50pm

thepronghorn wrote:
Jul 05 2018 3:26pm
Like madin88 said, measure the Rm, Kv, and no load losses at two different voltages, and then we will be able to compare these two motors performance wise (inductance would be nice as well for an indicator of the "controllability" of the motor). You have already covered their mechanical design fairly well. One measurement that would also be nice is the stator lamination thickness (careful inspection of the stator photo you posted indicates 0.5mm lams, but the picture quality wasn't high enough to easily count laminations).

Like others have said, some of your electrical design comments need a little clarification.

You mentioned that you liked the 100% magnet coverage, but usually a motor's torque/weight ratio is optimized somewhere closer to 80% coverage. The 80100 motor was designed with the intention of optimizing power/weight for model airplane use. For our applications, weight may be a smaller factor, but optimal magnet coverage still varies from motor to motor and user to user, so it is hard to say that the Revolt motor is definitively better than the 80100 in this category.

Spinningmagnets wasn't quite correct. What madin88 was pointing out is that the flat magnets cover 360/14=26 degrees of the rotor each which results in a maximum gap to their back iron (the rotor steel) of 2.6% of the motor's radius (exact solution is 1-sqrt(1-pi^2/14^2)). For a 80mm diameter motor, this results in a 1mm air (plus some epoxy) gap from the flat magnet to the curved back iron which means the back iron is much less effective at linking the magnet flux since the flux must jump across the 1mm gap.

Thicker stator teeth means less space for wire. This improves peak power capability but decreases continuous power handling. Again, specific motor design parameters are not necessarily good or bad, they are all varied by the motor designer in order to optimize for the motor's performance targets and constraints (speed, torque, power, weight, cost, size, etc.).

Thanks for the motor review. Others have posted varying reviews of Revolt motors in the past, but your in depth analysis is good content.
The lams are thinner than .5mm. I'd say they are .3mm. I pulled out my micrometer and set it to .3mm and held it over a single lamination. It looks like the same width. .5mm lets me see both sides of a lamination between the caliper jaws.

Testing the motor...
Let's just throw it out there...I don't know how to do any in depth testing. I can measure the inductance of the phases...that's just a meter and I have a 4 wire milliohm meter. I also have scopes and what not. What would you suggest?

What do you consider losses at no load? All motors at no load draw some amount of current as can be sen at a watt meter. Is this what you are referring to?
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Re: Revolt RV-series motor review and comparisons

Post by thepronghorn » Jul 05 2018 5:30pm

Generally it's easiest to measure the width of 10 or 20 lams.

The specs we need to characterize the performance of a motor are phase resistance, speed constant (aka Kv, rpm/volt is a common unit), and losses at no load at two different voltages. The page below discusses how to measure them all.

http://www.bavaria-direct.co.za/constants/

If you don't have a way of measuring rpm, you can scope two motor leads as you spin the motor and get the voltage and angular velocity from the bemf waveform.

Two no load points are useful so we can approximate the 1st and 2nd order losses as explained by crossbreak here.

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Re: Revolt RV-series motor review and comparisons

Post by ElectricGod » Jul 05 2018 5:46pm

thepronghorn wrote:
Jul 05 2018 5:30pm
Generally it's easiest to measure the width of 10 or 20 lams.

The specs we need to characterize the performance of a motor are phase resistance, speed constant (aka Kv, rpm/volt is a common unit), and losses at no load at two different voltages. The page below discusses how to measure them all.

http://www.bavaria-direct.co.za/constants/

If you don't have a way of measuring rpm, you can scope two motor leads as you spin the motor and get the voltage and angular velocity from the bemf waveform.

Two no load points are useful so we can approximate the 1st and 2nd order losses as explained by crossbreak here.
I have a laser tacho.
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Re: Revolt RV-series motor review and comparisons

Post by ElectricGod » Jul 07 2018 9:48pm

Not sure how much testing I'll get around to. I'll check phase resistance and possibly indictance, but that's probably all I'll get done.
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Re: Revolt RV-series motor review and comparisons

Post by larsb » Jul 08 2018 7:49am

Please, don't start a second wave of hype on the revolt motors. i was on the first and got burnt

The first lineup of revolt motors are crap, read my posts, there's plenty more reviewers here with issues.
Flawed design, poor quality control. Good at inflating specs.
They have a new lineup that could be better but since the first motors were so bad i wouldn't buy from them again.

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Re: Revolt RV-series motor review and comparisons

Post by John in CR » Jul 08 2018 9:16am

EG,

Great job on the physical review of the motor. Pick up a cheap inductance meter on ebay. It's good to check inductance and resistance phase-to-phase each way to make sure there's no mistakes in the winding (impossible to check visually), and the resistance is a critical measurement in understanding how much current it can handle.

To me the real test is no load current at 2 different voltages. With that, measured Kv and the physical attributes you have all the info for it to be put into Miles motor performance spreadsheet. Then we know efficiency at any current and voltage combination, which to me is the true measure of how good a motor is.

Why are you playing around with the little toy motor anyway when you have the best highest efficiency hubbie ever made? Get that HubMonster up and running pushing less than a 400lb all up load with the smallest tire that will fit. Feed it 100A battery side per controller X 2, and you'll be in electric transportation heaven, while you work on something lighter.

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Re: Revolt RV-series motor review and comparisons

Post by madin88 » Jul 08 2018 11:38am

ElectricGod wrote:
Jul 05 2018 1:00pm
Revolt claims the Pro and E are more powerful motors. I don't think the stators are larger or longer. Revolt presents very few details for the "regular" motors on their web site. It's hard to compare specs when they are not listed!

2-5kw for the RV-100-regular
3-6kw for the RV-100-Pro
6-11kw for the RV-100E


Whether those numbers are exaggerations or not is a guess right now, but 2kw continuous vs 6kw continuous out of the same size stator is impressive...if it's real. Honestly though, I already get about 4800 watts max out of a C80100. How could a larger stator with more copper do worse than that? IE: the "regular" motor ought to realistically be about 5kw continuous.
For the "regular" motors there are no specs, but for the "pro" and "E" versions almost everything is specified :wink:
The RV-100E has 84x60mm stator VS the the RV-100 Pro (and regular i guess) which is 84x45mm. Thats the reason for the huge difference in power between those two.
Even the thickness of the laminations and tghe phase-to-phase resistance of any available kV is listed, but only for the pro and E versions.

One really annoying thing are the performance graphs with logarithmic scale.
It makes the motors look really good on the first sight, but it is impossible to find out if peak ETA is more like 85% or 90%.
You only do this if you want to hide details on purpose. It's not much useful.
John in CR wrote:
Jul 08 2018 9:16am
To me the real test is no load current at 2 different voltages. With that, measured Kv and the physical attributes you have all the info for it to be put into Miles motor performance spreadsheet. Then we know efficiency at any current and voltage combination, which to me is the true measure of how good a motor is.
I found out that this is only one part you like to know for comparing different motors.
The problem is saturation which makes it hard to tell how much torque you really can get out of one motor at given current.
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Re: Revolt RV-series motor review and comparisons

Post by John in CR » Jul 08 2018 12:51pm

madin88 wrote:
Jul 08 2018 11:38am
John in CR wrote:
Jul 08 2018 9:16am
To me the real test is no load current at 2 different voltages. With that, measured Kv and the physical attributes you have all the info for it to be put into Miles motor performance spreadsheet. Then we know efficiency at any current and voltage combination, which to me is the true measure of how good a motor is.
I found out that this is only one part you like to know for comparing different motors.
The problem is saturation which makes it hard to tell how much torque you really can get out of one motor at given current.
Phase-to-phase resistance gives you a better idea about current limits than saturation. Running anywhere near saturation is only useful for drag races, because getting near saturation creates too much heat. Knowing Kv gives you the torque number, just not the torque limit. No load current lets you know the voltage limit unless the Kv is so high the physical rpm limits come into play. Efficiency trumps all because heat is our limitation, and the Revolt motors others have tested failed in efficiency and couldn't be run at near the power claimed. The telltale sign was the high no-load current. I bought one of their original 120's when they first came out, and it still sits in a box because I know it won't do what I was sold it could. Look at all the time Larsb invested trying to improve one. Sure saturation is good to know, but it's not so easy to measure. No load current tells so much more and is super easy to obtain.

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Re: Revolt RV-series motor review and comparisons

Post by ElectricGod » Jul 09 2018 3:17pm

John,

I have a decent inductance meter and milliohm meter (4 wire), I can check this stuff. Meant to do it already, but life is busy.

I can check RPM with my laser tacho at a 66 and 82 volts. I assume you want watt meter amperage at those voltages at WOT right?

Just for clarity, what's no load current? To me that means the motor is spinning at WOT and there is nothing on the motor shaft to load it down. Whatever the watt meter reads is the "no load current". Are we talking about the same thing?
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Re: Revolt RV-series motor review and comparisons

Post by ElectricGod » Jul 09 2018 6:00pm

larsb wrote:
Jul 08 2018 7:49am
Please, don't start a second wave of hype on the revolt motors. i was on the first and got burnt

The first lineup of revolt motors are crap, read my posts, there's plenty more reviewers here with issues.
Flawed design, poor quality control. Good at inflating specs.
They have a new lineup that could be better but since the first motors were so bad i wouldn't buy from them again.
I looked at your 120 pro rewind thread. Geez..that had to be hard to do! No wonder you did a wind or 2 a day and stopped.

For anyone else that cares, you can see that the Pro motor has curved magnets that the Regular does not.

I've posted the things I've found that I thought were mechanically wonky.

I have 41F halls, but they are too large to fit between the stator teeth and be flush with the stator faces, I don't want to damage the lamination's down into the stator stack so I'll make openings at the top and bottom of the teeth so I can add dual halls and that will create stator shorts only in the outer layers of the stack.
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Re: Revolt RV-series motor review and comparisons

Post by ElectricGod » Jul 09 2018 11:35pm

Checked a few things.

Phase resistance: 57.6-57.7 mOhms.

Inductance: .2 to .21 uH

I doubt that a phase is wound incorrectly with that small of a difference.
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