Does wiring include things like alternators?
Anyhoo, I built a pancake alternator by moving the electronics off to a computer fan, but to get it short enough I grounded one of the brushes directly to the frame of the alternator. Oops, that might have been a mistake. Pre-electronic regulator models grounded one brush and connected the other one to the indicator light to energize the rotor. Looks like the electronic versions work a little differently. So now I'm trying to come up with a voltage regulator to control the danged thing. (It charges just fine when the remaining brush is connected to +12v.)
I'd prefer an off the shelf solution for easy repairability, however a custom circuit is not out of the question. The windings are typical GM Delcotron S10, although I have added a center lead to the wye stator winding in an attempt to us a Denso regulator that looked appealing but has not worked, possibly because of the case grounded rotor winding brush.
So far the regulators I've found circuits for do not have a direct ground connection for either side of the rotor. I don't know for sure if this is a problem or not.
Has anybody delved into these mysteries?
Jim
What you need Jim, is an old Bosch external voltage regulator.
They were made to control the positive feed to the field.
Bosch # 043 903 803A Delco # E695 Ford # A73CX10316KA
They were used on tons of vehicles in the 70's and 80's
The D+, or red, terminal is switched battery power. The D-, or black, terminal is ground to the alt case. The DF, or green, terminal is power out to the field brush.
They come housed in a small can with two mounting holes. No extra cooling is required.
A small diode trio will be needed to run your idiot light if you use one.
Cheers
Fred
Great, thanks Fred.
What do you think of the Transpo D7024 regulator? Solid state, adjustable...if it'll work.
It's a "B" circuit design which means that it controls power not ground.
So it should work well.
And the adjustment is a handy feature.
It's not an OEM part so you might want to buy an extra just in case.
Cheers
Fred
Thanks Fred. I was wondering what that "B" circuit designation meant. (Confusing, it was always used as "B - ") Seems there are plenty of B circuit regulators out there though. Does "A" circuit mean they control the ground?
Jim
You betcha. It's a holdout from the days of the generator.
Good to know. I ordered the D7024. About $65 shipped but it looks good, is small, and I think it'll fit on my mounting location easily. Using a sealed connector on it should be easy too.
Jim
OK this worked out just fine. The Transpo regulator was easy to fit, wire up, and the alternator charges with it. I have not adjusted the output yet.
But, I thought I'd see if I could find a better field winding (stator). I'm showing a discharge from idle speed up to about 1500 rpm and I'd rather have good charging at low speed than big amps at high speed. As I understand it, more turns of finer wire give better low speed charging but lower total output where fewer turns of heavier wire gives higher total amperage but lower charging at low speed. I already have a couple of the higher output windings but what I think I need is one that will put out over 40 amps or so but will give about 20 amps at idle. Anyone have suggestions?
Jim
More turns of finer wire on the stator will do exactly what you said Jim.
There are other methods though.
A stator with more poles or a larger internal diameter will do the same thing.
Speeding up the alternator at idle has the same effect.
Using a field rotor with more poles or a larger diameter gets you there as well. Most low speed ones tend to have 14 or more poles.
These mods make the alternator see more and faster pole interactions per rpm.
The problem is that all of these sacrifice high speed amperage for low speed amperage.
Probably not an issue though if you only want it to max out at 40 amps.
Another option that doesn't sacrifice high speed amperage is a field winding of heavier and or more windings.
This makes the field much stronger. The down side is shortened brush life. Which can be significant.
The fix is a brushless design. The field coil is mounted solidly to the alternator case and the field pole pieces rotate around it.
This way the field coil can be hard wired and wire size is no longer an issue.
Might even let you shorten the alternator more if brushes are out of the way.
I have a couple of shots of a Bosch alternator that runs this way.
IMGP9449.JPG
IMGP9450.JPG
IMGP9451.JPG
IMGP9452.JPG
The pictures are on a 2" grid to give you some idea of size.
The alternator this came from is 180 amps so 40 should be easy.
Another thought just struck me.
Your megasquirt should be able to run the alternator. Most regulators don't put full voltage into the field. An output that would full field the alternator when needed might be all you need. If you could configure a PWM output you could throw the regulator away.
Anyway starting to ramble again.......
Cheers
Fred
Interesting thoughts. I'm not sure I understood much of it, but... It appears from 10SI output charts that the 63A stator winding gives the fastest rise of charging current so I've installed one of those and will see how that works. Next step will be to crank up the regulator adjustment a bit and see what that does.
Ultimately though I'm not really satisfied with the 10SI based unit and will eventually want to build a pancake unit that is slightly shorter with a higher output. That removable rotor winding is quite interesting, but too long unless the brushes and slip rings make use of the bolt on cover plate somehow.
Jim
The rotor winding is stationary. There are no brushes or slip rings required.
The entire unit is 3.25" deep with room to shave another 0.50" if needed.
But this is just an example. Machining one up from scratch would be relatively easy.
You could build an alternator that isn't much thicker than your stator.
Cheers
Fred
Yes but how do you control the charge? I'm very familiar with motorcycle alternators (PM type) but they generally "waste" the excess charge, the basic technique is by shunting anything over a zener breakdown voltage to ground. OK with small alternators but not so great with larger ones. I'd be curious how that Bosch does it.
The charging/rpm curves on the CS series (GM) looks quite good, especially the CS140 but I expect they are rather thick. My limiting factor is rotor length so a short, large diameter rotor would be good, but the brushes typically take up a lot of room. Often the bearings and slip rings take more space than the rotor. On my 10SI based unit I placed one brush in a bore in the end of the shaft to shorten the unit adequately which is why one end of the rotor winding is grounded.
But I wonder if a design where the bearings are inside the rotor might not work.
Jim
The charge is controlled by a normal voltage regulator.
I didn't show the entire alternator, just the rotor, as the stator is completely conventional.
I suspect that's where the confusion is coming in.
Have you thought about a brush package like the lucas and chrysler alternators use?
The brushes run in the same plane as the rotor shaft. It would be easy to swap the whole affair over to the pulley side of the alternator and gain tons of room.
What about the old chrysler alternators? They are very slim to start with. If you remote mount the diode pack and move the brush package, you could come up with a very skinny alternator. Units up to 100 amps are pretty common.
Running a bearing inside the rotor makes good sense. You could actually support the entire rotor from the rear. If the rotor could accommodate a bore for two bearings it could be supported by a single pin from the back. No front bearing to get in the way.
So correct me if I'm wrong Fred, and it seems I have to be, but if the rotor doesn't spin but the stator is conventional, where is the relative motion? Obviously I've missed something somewhere. If there are no brushes then the only way I can think of for the moving part to have windings is if it is an induction type configuration. Otherwise there'd be permanent magnets, yes?
Now brushless 3 phase motors are common, and much favored in servo systems where motion is precisely controlled even at full speed, and they are quite powerful. So a generator should be configurable the same way I would think. Is this where you are going with this?
In that case it makes little difference whether it is the rotor or stator that is held stationary and servo hub motors for scooters and such are all the rage presently. Maybe something similar could work. http://www.creative-robotics.com/About-HUBee-Wheels
Seems one limitation is the diameter of the driven pulley which requires otherwise dead length. Perhaps use a fixed non-rotating shaft and put the brushes inside the pulley? Some ingenious configuration of the fan might also leave more length for the rotor and stator. I have already removed the electronics to a remote location.
If we could come up with a nice compact configuration at least theoretically, then perhaps we could adapt some existing components. Interestingly, the Chrysler unit is not as short as it looks.
Jim
The rotor spins, but the field coil is stationary inside of it. That eliminates the need for brushes.
In the last picture I am holding the field coil. It drops into the rotor which is supported on either end by a bearing. The field coil mounts solidly to the case with the screws that are in the picture.
You are right whether the stator or the rotor turns doesn't really matter. Due to the amount of power being transferred its just easier to have the rotor turn.
But if you constructed a stator that went inside of the field, basically an inside out alternator. The rotating field coil could actually be the pulley.
As far as the fan. It doesn't have to be part of the alternator. A remote mount fan with some ducting would free up some length. Most of the heat generated is from the diode pack anyway so the cooling load would be very small at the alternator itself.
Cheers
HA! Hadn't thought of that one, sort of like an A/C clutch. Well, there's a thought. Quite ingenious really. I like that a lot. And with the not-rotating winding it could be severely overdriven.
Only it is rather long. Looks like about 4.5" plus front cover with bearing plus pulley and fan. I have 4" to the back side of the fan belt on mine and that includes bearings and brushes.
But the rotor could go bigger in diameter without hurting anything. Now that is the tricky part, finding a suitable rotor. But If you took that one, put the bearings inside with the rear supported shaft like you mentioned, reversed the thing so the wires come out the back plate, cut a pulley into a slight overhang on the front, and cut down the thickness of the back plate and the overlap it just might make it. Might even be room for a small fan, though actually I expect the rotor could do that job for itself. Best of all, you could weld on it without worrying about the wires so it'd be pretty easy to modify.
Wouldn't have any documentation on that unit handy would you? The largest diameter with the shortest length would be the way to go I'd think.
Jim
Jim, Fred,
Excuse the intrusion but I seriously looked at the Ford Bullit alternator for my project before going in a different direction. It's supposed to be 4" thick. I wonder if you might be able to use the rotor from this unit?
http://www.precisionenginetech.com/project-engine-builds/2010/12/14/project-flathead-part-6/
No problem Jim. This thing is only 3.20" long (excluding bearings)
It has more than enough meat to accommodate internal bearings.
So if you follow me, cut off the input shaft and counter bore the front of the rotor 2.750" to take some good old 6203 bearings (and retaining clips etc.).
Build a suitable mounting plate with a peg to mount the rotor and bearings onto. Bolt the field coil onto the mounting plate.
Press the rotor into place and use what was the rear bearing spigot as the new pulley mount.
Mount the stator to the backing plate and VOILA! No front cover needed at all.
You end up with an alternator that is roughly 3.40" thick to the back of the pulley/belt.
And the best part...the alternator is from a Land Rover. So you actually have proper parts on the MG.
It's from the 03-05 MKIII RangeRover so it's really a BMW part which means there are tons of them in the wrecking yards. The ones I'm familiar with came on the M62 4.4L v8 so 97 and newer 540/740 and 840 models.
The smallest one is 150amps so no overdriving should be needed. If you find one they are watercooled not the later aircooled version.
Cheers
Very cool.
Scott, that is a great find, sounds like it might fit, and the only challenge is mounting it perhaps. Very close on the length though.
Fred, sounds like I'll have to visit my old BMW buddy and look at parts. I think it's a great plan and can result in a fantastic alternator for tight quarters.
So a plan is in the works. Things will move a bit slower from this point forward though because:
I fitted my modded 10SI with a new 63 amp stator which I cannibalized from a 30 dollar reman (the reman is getting an older 100A winding and may be used for the Chump car) and while I had it apart I improved the conductance in the grounded brush circuit and cleaned away the grease that had leaked out of the bearing onto that brush. Reinstalled it pegged the 50A ammeter then settled down to a 15 amp charge at idle. That'll do fine for now, but long term durability of the ground brush may be an issue. If it goes, the bearings will be next.
So, I want to continue pursuing this. But other matters are pressing at the moment and I'll have to put off the parts run. I'll also have to rig some sort of an ammeter shunt if I use one of these.
Jim
Yesterday I stopped by PepBoys to look at alternators. They didn't have the Mustang Cobra GT unit in stock though. It was about $180. I didn't have time to ask about the Bosch unit. I have a friend across town who might have one of those lying around but it'll be awhile before I can get over there. I didn't know which one to ask for anyway.
The next step in this design exercise seems to get my hands on the parts., but if anyone has suitable bits they'd like to send over in the meantime that could help move things along.
At this point I'm thinking of about a 5/16" thick plate to bolt directly to the pads on the end of the head (3 bosses on the Buick head, on my car currently used for the motor mount and alternator pivot). Mounted and welded into this plate, a stub shaft 1" in diameter with a central bore. On the back of the mounting plate, a groove from there to the edge. This is a pathway for the rotor winding leads. A termination block on the edge of the plate. 3 holes drilled and tapped into the end of the stub shaft to secure the rotor winding which also holds the sealed bearings in place on the shaft. Mounting bosses on the plate for the stator winding, which connects to the termination block also.
Two sealed bearings pressed into a central bore in the rotor which is mounted with the winding inserted from the front. A hollow pulley is pressed and welded to a machined step on the end of the rotor.
And I think that's about it really. The remote package consists of a diode bridge rectifier, the 12SI is an attractive package or something of that general type, and a number of compact regulators are available such as the Transpo I'm using, mounted on a pancake fan which can be switched on when the rotor is energized (something I haven't incorporated yet).
Overall length for this unit should be very close to 3-1/2" to the back of the pulley belt, short enough to go in front of almost any cylinder head and belt up to the crank. The back plate could be drilled for any cylinder head boss pattern. Adjustability would require one or two slots and maybe some other trickery. The rotor would act as its own fan.
Do we need such a piece? Probably not, but it could help with accessory packaging issues. I may build one just because not having brushes makes the unit more reliable.
Jim
I tried driving the pancake fan under the electronics package with the rotor control signal from the regulator and it worked great. The fan draws 1/4 amp so it increases regulator output by probably about 33% if the full current draw of the rotor winding is 3/4 amp. But that winding is less than 12 ohms resistance, probably closer to 3-4 ohms and discounting inductance would mean about a 3-4 amp draw at full charge and 1/4 amp is less than 10% of that. So I doubt that burning out the regulator will be a problem. I'm willing to chance it.
This way with the ignition on but the engine not running the fan does not run. At idle the fan creates quite a nice breeze past the parts while charging at 10 amps, and at initial startup the alternator still pegs the 50 amp ammeter. Voltage output is steady at 14v with no adjustments made. And the harder the alternator charges, the harder the fan will run.
Now obviously measuring the temp to control the fan would be better, but this works without any extra wiring, sensors, or controls. Dead simple in fact, simply wire the fan across the field winding. Better still, I believe it'll work just fine with Fred's stationary winding setup.
Jim
Hey Fred, I got a box in the mail today, something with a rotor in it looking frighteningly similar to yours! That's a hefty rascal, isn't it?
So as soon as I get a chance I'll see what bearings I have that'll work and give this a try. Pretty precise fit between the rotor and the end plate of course.
Jim
No problem Jim,
I figured that you would get to it long before I would.
Cheers
Fred
I hope so. For the next couple weeks I'm pretty tied up with working on the 3D printer and then wiring the MG when I can but I'll look for the odd moments to work on the bearing bores.
Incidentally, the control package worked out pretty nice and I built an aluminum sheet metal cover for it which I plan to anodize some time this winter. It vents the fan exhaust out the back and acts as a heat shield from the headers.
Jim
IMG_0001.JPG
Fred, you might hold on to the field winding for that alternator if you still have it and it's any good. That'd strike me as a necessary part. I have yet to look at the number of poles and diameter to see how they compare to others but I'm not sure there's very much interchangeability there.
Jim
Sadly, that stator has left the building.
The rotor size is pretty standard for a Bosch alternator so shouldn't be too difficult to find a stator that would fit.
There's a lot of meat there so you could turn it down to fit if needed.
Cheers
Fred
A bit more info:
The Bosch rotor would have to be cut down close to .300" (8mm) to run inside the Delco S10 field coil, probably inadvisable. The Bosch unit is simply massive by comparison, and against a Denso rotor? That looks like a toy. It's also about twice as deep as the S10. I didn't measure it but it makes me wonder if there might not be a smaller version of that Bosch unit that would be more suitable for our use?
Also, the Bosch is a 14 pole rotor where Delco, Denso, and Ford are 12 pole so the field windings would not work anyway. Perhaps that is a function of the larger diameter.
Jim
The Stator doesn't care how many poles that the rotor has Jim. It's actually to your advantage to have more as it makes the stator think that the alternator is running faster than it is. That allows more charge at lower rpm's.
That rotor is pretty stout so taking 8mm off of it shouldn't be a problem. I can't remember it's actual diameter, but if you could measure it for me I'll check my stash of alternators for a stator that is close.
Cheers
Fred
I measure it at 112mm or 4.380" diameter. The GM's seem to run close to 1/8" clearance on the diameter, which seems like a lot to me. My concern about cutting it down was more about losing magnetic flux (because or the reinforcing ring) than strength, I'm sure it's plenty strong.
About the pole number, yeah, I do think it makes a difference on the count, or at least can maybe depending on how the stator is wound. Normally I think the stator has three times the number of poles as the rotor so each winding lines up with a + or - pole on each winding at the same time so that the voltages add. Otherwise I think the poles on the stator would be fighting each other.
But there could be other ways to wind it and I'm no authority.
Jim
Jim, in the theoretical world the pole count of the rotor vs the pole count of the stator does matter.
In the real world it's a different story. If the rotor poles matched the stator poles the alternator would howl like a siren. And break down the winding's very quickly. Even when mismatched the alternator is still very noisy. That's also why the GM alt's, as well as others, have such a large clearance. Less engineering required to keep it quiet.
So the fix is to taper the rotor poles so that engagement of the two is gradual.
It's not perfect but this reduces noise and vibration under load. And has the advantage of increasing the average efficiency.
Albeit at the expense of peak efficiency. A lot of which can be reclaimed with a lesser clearance.
I agree that the reinforcing ring is a deficiency, but a necessary one as it joins the two forged sections.
I think that the massively increased field coil power more than makes up for that shortcoming though.
I'll check through my carefully archived vintage automotive parts supply (junk pile) this weekend to see what might fit that rotor better.
Cheers
Fred
I found a bunch of stators that will fit for you Jim.
The easiest one to find is the mid 90's and newer bosch 120amp alternator. It came standard on quite a few European cars. BMW, VW, Audi, Volvo etc.
Should be an easy find at a wrecker.
Cheers
Fred
Cool.
I'm still going to be tied up on the 3D machine for awhile but I'll get back to it as soon as I can.
Jim