The "Altermotor" (A Build Thread)

[modern_messiah]

Hey hey!

Yes I realise there are a few threads regarding the use of alternators to create a motor. They can be found (at least the 2 best ones) here and here. They have some good general information but neither actually appear to deal with converting the motor itself. Not that there is much to do, but I will be going to a greater level of customisation than it’s probably worth. But hey – I’m like that.

I plan to someday (in the reasonably near future) convert a car into a track EV monster. But having had no prior experience with electric motors at all I don’t want to start totally un-prepared. OTS the shelf is all well and good but it doesn’t challenge me enough. I’m a tinkerer, I like hands on. I feel this is a good way to get the ball rolling. Besides, it may turn out to be useful for something!

What I hope will make this thread a worthwhile read is that I intend to record my efforts in actually converting an alternator into a permanent magnet (PM) motor - that is replace the stock ‘claw’ rotor with a custom made PM magnet rotor instead. I also want to gut out the unimportant pieces, clean up the left over parts, modify the housing and if the benefits can be justified possibly rewind the stator.

I will use this thread to show people what I’m doing and to ask questions of people in the know. Hopefully this will keep the relevant questions and answers in one easy to find place instead of spread over 50+ threads. Makes sense in my head anyway!

Enough rambling and onto the ‘Altermotor’. I managed to score a 24V truck alternator off a friend for free. Other than those details that’s all I know. It’s been sitting on his work bench for who knows how long and is fairly dirty. In my sheer excitement to finally have one in my hands (I’ve been looking into doing this for a few months now but have been to busy) I forgot to take a photo before I did anything. But meh, it’s pretty unexciting. Here’s a photo of the whole thing apart in it’s primary peices:



It was taken with my phone so apologies for the photo quality. The rotor coil on the far right and the claw rotor on the far left (the rusty bit around the shiny axle) will both go. When I get the rotor claw off I will design a PM magnet holder that will slot straight into its place. The stator has 18 teeth (or coils) on it so I’ll be looking to fit 16 magnets (or 8 pole pairs) to the new rotor.

Anywho....my first questions:

1) My first port of call is a massive cleanup. Can anyone suggest a good cleaning agent that I can use on the stator/windings/everything else? Or is a rub down with a dry cloth the most I should do? I obviously don’t want to damage the insulation coatings on the laminations or coils...

2) I should also probably decide at this point whether a rewind is on the cards or not.It is currently wound with doubled stranded (as in 2 pieces of wire for one turn) of what I think (rough measurement using a ruler) is 18AWG wire. Thicker wire will obviously allow for higher currents but what are my chances of being able to wind a thicker strand? I’ve never done it before but I’m willing to put in the time and effort. I have read Thuds rewind thread but that's fairly motor specific...

So yeah, I’ll leave it there for now I think. Thanks for reading and any information to my questions above, or general comments, insults and jokes about my little project would be greatly appreciated.

Cheers!

- Matt

 

[dynamo dave]

I ASK THE FRIEND AT WORK WHO DOES ALTERNATOR REPAIR ON THE SIDE WHAT HE USED TO CLEAN THE STATOR.AND HE TOLD ME "SHOUT" AND HOT WATER. THEN DRYS IT IN THE OVEN ON LOW FOR FOUR HOURS. I HAVE STEAM CLEANED SOME STATORS AT WORK THEN DRIED THEM. GOOD LUCK HAVE FUN BE SAFE

 

[modern_messiah]

I ASK THE FRIEND AT WORK WHO DOES ALTERNATOR REPAIR ON THE SIDE WHAT HE USED TO CLEAN THE STATOR.AND HE TOLD ME "SHOUT" AND HOT WATER. THEN DRYS IT IN THE OVEN ON LOW FOR FOUR HOURS. I HAVE STEAM CLEANED SOME STATORS AT WORK THEN DRIED THEM. GOOD LUCK HAVE FUN BE SAFE

So stain remover...makes sense because it doesnt eat away at fabric but then again everything reacts differently, especially metals and plastics. I might do some tests before I try it on the actual stator. Thanks for the info.

 

[jonescg]

I ASK THE FRIEND AT WORK WHO DOES ALTERNATOR REPAIR ON THE SIDE WHAT HE USED TO CLEAN THE STATOR.AND HE TOLD ME "SHOUT" AND HOT WATER. THEN DRYS IT IN THE OVEN ON LOW FOR FOUR HOURS. I HAVE STEAM CLEANED SOME STATORS AT WORK THEN DRIED THEM. GOOD LUCK HAVE FUN BE SAFE

Based on your caps lock issues I'm guessing you SHOUT quite a lot :lol:

 

[modern_messiah]

Based on your caps lock issues I'm guessing you SHOUT quite a lot

Lol, I was thinking the same thing haha.

 

[modern_messiah]

The stator cleaned (it may not appear to be so but I blame my crappy camera phone and the poor lighting making it look so dirty) and some better winding terminations added. Hopefully my soldering job holds up…



One issue I’ve got that is crossing my mind and I can’t seem to shake is how the stator is wound. It definitely has 18 coils. Going by the winding calculator here this would imply that a rotor of 16 magnets (8 pole pairs) would be ideal. However when inspecting the stock rotor, the number of ‘fingers’ on the claw is 12.

So this makes me ask 2 questions that hopefully (I say hopefully because I imagine this thread would not generate much interest) someone can explain for me:

1) Would alternator windings be done using the same winding patterns as their numerically identical motor cousins?

2) In turn, would this alternator stator be wound in a way that corresponds to one of the two 18 coil winding patterns listed in the link mentioned previous? I guess I could check how it is wound with a battery and my home made “magnetic polarity detector”. The stator is wound too tightly for a visual inspection. If it does correspond to either the “ABCABC etc” or “AaBbCc etc” pattern then I’m good to go, but if not then I will have to rewind it…

I’m quietly confident just making a 12 magnet rotor will work without issue as I have seen several videos of people running alternators as motors without any modifications using nothing but an ESC to control it. All a PM rotor is doing is taking away the need to power the rotor claw as per a normal alternator (but hopefully making it a more powerful and efficient motor!)

Thoughts?

 

[dynamo dave]

Hi modern. I think what you have is a consequent pole connection. The math works for this pattern. I hope I am reading your discription right. 12 claws .Is that 6 from one end and 6 from the other. Then it is a 12pole alternator. Here is the neat part.You can check with your magnetic probe.Draw a circle at 9:00 outside the circle put a North pole now at 3:00 put another North pole.(this is so great) Then at 12:00 and 6:00 South poles will be created as a conseqent of the two like poles repelling each other inside the rotor/ armature. 18 coils divided by 3phase =6salient all the same porlarity with 6consequent poles inbetween them. totaling 12. What did you finally use to clean the stator? looks good .You are good to go if your polarity test proves out. Try to get to the wye point and one phase if is wye wound delta will take more figuring.jonescg your AL winding has merit. ENJOY THE JOURNEY

 

[modern_messiah]

Hey Dave,

I used some stain remover and warm water like you said. I also used a soft bristle tooth-brush and gently scrubbed the whole thing. I then backed it at 105 degrees in my oven for 2 hours to properly dry it out. Worked really well!

Thanks for the advice on how to check the windings. It's hard to follow but I think I get it. Time will tell I suppose.

 

[dynamo dave]

Thanks for the feedback Modern. I just wanted to post this as close to the Consequent pole post as possible. That is when you energize the staor winding for the magnetic probe test.You will be using either several D cells,a lantern battery, or a car battery with a tail light in series with it to limit the currrent.The stator has very little resistance and no CEMF during this test.I am new to this on line stuff and I realized anyone could be reading this. We do not want them to fry anything. Maybe keyword search consequent pole connection will give you more info. ENJOY THE JOURNEY

 

[modern_messiah]

So I got my hands a hulking big chunk of steel, found a local guy who is capable of doing the work, drew (is that the right word?) up a detailed plan (annoyingly he required it in inches) and am scheduled to have myself a shiny new rotor custom turned next Friday for AU$50. Bargain. The plan is as follows :



The magnets are thin but being rare earth should definitely produce more grunt than the stock rotor. The guy doing the machining for me builds race cars and parts for them for a living and has some glue that he says he uses "to literally glue cars together" to aid in attaching the magnets because machining flat spots for the magnets would be very difficult though possible - but he is doing me a favour so I wanted to keep it as simple as possible for him. I will wrap the whole thing in Carbon Fiber as well to be safe. He is also going to produce a sleeve from some plastic the glue can't stick to so I can get a perfectly round fit before applying the Carbon Fiber.

 

[modern_messiah]

This (left) took myself and the guy who did the machining FAR longer to do than we anticipated, and we're not even close to done yet. At least it's in a more workable form than the piece of steel it came from (right) - it took 3 hours just to get the end and sides smooth. We jammed his lathe twice trying to part the good bit from the bad and in the end I had to take it to a machine shop who had a metal ban-saw to get them to cut it off. I'm putting way too much effort into this lol.



I've got 60 small rare earth magnets in the post that I plan to use to create the 12 poles of the rotor as per the diagram below. If it doesn't work it's only $30 down the toilet and 60 very strong fridge magnets lol. I'm sure I'll find a use for them. Ignore some of the circles on the drawing as they are hang overs from my own musings...and there will be 12 sets of 5 magnets of course. I just got lazy (again) and didn't bother finishing the drawing as it's pretty obvious to me what's going on!

 

[Harold in CR]

Keep going. 8) 8) I, for one, am interested in your project. 8) 8)

 

[modern_messiah]

Unfortunately it seems I may be in possession of 65 next to useless magnets

My 'plan' to use 5 to make a single pole has not worked as the magnets are impossible to place touching each other with the same poles pointing outwards from the rotor. I actually managed to snap one magnet in half(!) trying to get them side by side. I thought this might be the case but took a punt anyway. The term "Fail" seems appropriate.

I'd use the magnets individually but 12 magnets won't provide anywhere near enough coverage. I considered moving up to a 20 pole, 12 tooth motor (20-12) but the stator is wound for an 8-12 combination and probably won't work if I go 20-12 without a rewire - something I want to avoid doing for the time being.

Could I possibly use 3 instead of 5 to make the poles? So take the incomplete diagram above, and remove the magnet either side of the centre magnet for each pole. The magnets in each pole would all have the same magnetic pole pointing outwards. There would now be a gap between them, but the group of magnets would be attracted/repelled by the same tooth at any given moment. I'm just worried that the air gap between the magnets will cause issues and I'm not technically inclined enough (yet) to determine how detrimental this would be to the performance of the motor.

Any ideas?

 

[Harold in CR]

Somewhere I saw a configuration, where the magnets were seated in staggered design, corner to corner, running around the rotor. This was for making a new rotor for wind generators. Would that possibly work ?? Corner to corner would eliminate the opposing forces, nearly to non-existance, correct ??

Let me do some Googling to see if I can find that info. It might have been for AC motors, to use as induction generators ??

An alternator is an AC generator-motor, correct ??

 

[Harold in CR]

Finally found a photo that's somewhat what I was trying to say. This guy has converted a motor to PM. Isn't this roughly what you are trying to do by using those small magnets ??

Maybe I don't follow your idea ??

 

[modern_messiah]

Yes and alternator is an AC generator. I think I understand the example you are talking about. Is the example motor you are talking about one where he then stuck small triangular pieces of metal on top of the magnets? This is not very optimal for a motor though I don't fully understand the principles involved.

For an example of what I propose to do see my last post in this thread. I tried it last night and it seems to work as I thought it would - even with the gaps between the magnets, the larger test magnet I waved over the top of the arrangement appeared to be repelled and attracted by all 3 magnets - it wasn't trying to be pulled into the gaps between them.

It's not optimal but it looks as if it works so I'll probably just go with that. Larger single magnets would be ideal, but the air gap between the magnets and the stator is over 5mm if I use sufficiently large magnets and I feel this would be MORE detrimental than the setup I am proposing.

 

[Harold in CR]

DAMMit. Looks like I didn't get the photo posted in my last response.

Here is what I have to show. Yes, these are round magnets, but, you should get the idea of how they are staggered.

No, I am not familiar with adding metal pieces on top of the magnets ??



Once the epoxy sets, most guys put a cylinder around the whole magnet array and pour epoxy inside, to get a nice solid rotor and hold the magnets firmly. The one I showed is a converted 4KW AC motor.

 

[modern_messiah]

I'll be totally honest and say that I have no idea what staggering the magnets will do to help - they are still too close to each other to do what I want to do. The solution I have at the moment seems to be OK though I won't know for sure until I start the motor up for the first time.

And the epoxy idea was already going to be used to help hold the magnets on there tightly. In runners are much more susceptible to flying magnets than out runners

 

[Harold in CR]

Yes, you are right about inrunners v outrunners. That photo is not exactly what I wanted to show. By staggering the magnets, you can get them close together without repelling. Somehow, I thought you were building an inrunner rotor.

Doesn't matter. You sound confident in your solution, so, all is well, Maybe.