48v delco alternator?

Geo-TH,In

Well-known Member
Is it possible to change the voltage regulator on a delco alternator to make 48 volts. I say NO. You would have to apply 4 times more voltage to the armature and IMHO armature will become toast, not to mention the stator or diodes.

I have read that it's possible to convert a delco to a 24 v alternator, but 48v???

I've read where 48v alternators are used on windmills and they use permant magnets in the armature.

What say the experts? BTW, this isn't my idea, so don't call me names, please:)
George
 
Generally and alternator voltage can be changed by just changing the voltage regulator. How well they stand up to continual use at the higher voltage may be a different matter.
 
Most automotive alternators will develop 60 - 90+ volts when open circuited - ie. not connected to a battery. (A battery acts as a stabilizing ballast to the alternator output).

Presuming you can locate a suitable regulator, a Delco probably CAN successfully charge a 48 volt system. Issue is whether the rectifier diodes will hold up working at this higher voltage (they probably will). More problematic is whether the field/stator windings' insulation can withstand the greater "I squared R" heating losses that will be developed.

I'd suggest starting with a 24 volt Delco (plenty of them on Ebay), apply a custom-built regulator to it and see what you get.

----

Not certain why many wind turbines use permanent magnet fields. I suspect it's for efficiency (no energy lost energizing field windings) and better low RPM performance. The downside is regulating a PM field alternator is more difficult/expensive.
 
Bob,
The current won't be any larger than the alternator's max rating. The resistance of the stator is the same, therefore the I squared R won't be a problem.

My concern is can the armature handle it? If you have an alternator say rated at 100 amps, should you push it to 100% or use some current less than 100%?

Last, where can you get a 48 volt regulator? The alternator will be connected to 4 12v batteries in series.

George
 
They do use 48 volt alternators on windmills.... but they are specifically wound for the purpose. Actually, the ones I've seen are 'axial' type rather than the conventional radial automotive type. It's a very different beast. Don't know how an auto type would fair at 48v but I suspect it would work as long as you don't overdo the current.

Rod
 
Hello George Marsh,

Voltage output of an alternator is about 90V A/C.
So you can get 90V dc if you rectify the voltage , without any step down transformer. Regulator assy will step it down and rectify it to the needed voltage. In automotive applications that voltage is 13.8 to 14.2 volts DC. The regulator is what will give you the output. I would think that if you the volt amp thing and keep the wattage the same as the original output, all will be well. Let me know if you try it.

Guido.
 
You can get 110 volts from an alternator.Just put 12 volts on the armature.I did it,ran a skil saw with a 5 hp briggs.
 
George, with all due respect, I SAY YES

Wellllllllll lets put our electrical thinking caps on.....

FIRST LETS GET THE TERMINOLOGY CORRECT: In an Alternator, the rotating component through which current is passsed via the slip rings to produce a rotating magnetic field IS CALLED THE ROTOR........The stationary coils of wire into which voltage is induced via a passing magnetic field IS CALLED THE STATOR. The Stators output is AC so its necessary to rectify it in order to produce DC charging voltage.

If you want to increase the output of an Alternator you can 1) Spin it faster or 2) Increase the Rotors magnetic field strength by pumping more current through it (controlling that rotor current is what the regulator does)

So long as the rotor windings will handle the extra current and the I Squared R heat can be sufficiently dissipated, enough current can pass through the rotor to likely yield a rectified loaded outout voltage of 48 VDC.

Next is the Stators ability to withstand the voltage (12 versus 48) and I think that wouldnt be any problem.

Next is the Stators ability to withstand the current youre going to pull out of the 48 volt alternator. At the higher 48 volts youre likely NOT going to pull the current (like 60 amps) that you were at 12 volts and its my best "guess" the Stator at 48 volts can supply the necessary charging current (but that depends on the load so we cant really say for sure) so the I Squared R heat dissipation wont be much if any more then when operated at 12 volts (Provided of course youre running at lower amps at 48 volts then when used at 12).

SO ITS MY OPINION A 12 VOLT ALTERNATOR YES CAN BE MODIFIED FOR 48 VOLT OPERATION. HOWEVER the heat dissipation has to be dealt with, so I doubt you can pump the same current as it does at 12 volts as if youre configured for 48 volts.

12 Volts at 60 amps means the Stator must dissipate 720 watts so at 48 volts thats 15 amps for 720 watts. The heat generated in the Stator is I Squared R and regardless if youre running at 12 or 24 or 48 volts I doubt it can dissipate a lot more heat, so at 48 volts I figure you cant still deliver 60 amps like it does at 12 volts (maybe 15 amps though)

Bob M (Mechanical Engineer understands heat dissipation better then me) and Janicholson am I wrong????

John T
 
JohnT,
You may call the rotating part of any motor the rotor. I was always taught the moving part of any electromagnetic device is called the armature. The stationary part the stator. I really don't care what we call it. I think we both know that I was referring to the moving part of the alternator.

I really want to know if there is a 48 volt delco regulator or how to make a voltage regulator to charge four 12 volt batteries in series. That will require a voltage from the alternator to be about 56-58 volts. Actually a mutual friend of ours called me and wants to build one. He claims he can make a 12 v delco put out 24 volts. I told him we could use 2 delco in series and isolate the ground of one of the alternators, but he only wants to use one delco.


Found this defination for armature:

In electrical engineering, an armature generally refers to one of the two principal electrical components of an electromechanical machine — generally in a motor or generator — but it may also mean the pole piece of a permanent magnet or electromagnet, or the moving iron part of a solenoid or relay.

ROTOR/ARMATURE :)

George
 
George, you are trying to do things I did 35 years ago.By disconnecting the battery load from the alternator and applying 12 volts to the rotor you got 100 volts DC easy.You could run skil saws and drills.Most saws and drills do not have DC rated switches.I sold a booklet called Alternator Secrets for many years for 3 bucks that explained how to do it.I built a solid state regulator for my rig because the 12 volt battery had to be recharged.48 volts would be no problem.Been there done that.DC is hard on switches because of a long arc when switched off.
 
I agree with the others, it is easily done. The alternator will be limited on the amperage, not as much the voltage.
 

I have plans somewhere to make an adjustable output Ford alternator.
A guy used it for a welder.

However if the output voltage is boosted by 4X the output current would have to be reduced to 1/4 of the 12 volt rated current or the alternator would fry. Simple ohms law and watts.
 
No problem, people are free to call the rotor a widget far as Im concerned lol. When talking ALTERNATORS I refer to the devices as the Rotor and Stator, and when talking GENERATORS I refer to the devices and the Armature and Fields, its just how I was taught and the commonly understood terminology used in the trade by engineers and technicians.

Okay you say NO but I still say YES (regardless what the devices are called) its indeed possible to make a 12 volt alternator charge 48 volts.

Thats my story n Ima stickin to it

Take care George, fun chat, best wishes n God Bless
 
OK, HOW DO I MAKE A 48 VOLT REGULATOR for a delco or where can I buy one?????????
THANKS,
george
 
Despite those who say NO, I still say YES its possible to do that, and I just remembered at one time I had a device (maybe from JC Whitney???) where you took a car alternator and wired it to ths black box and it could be used to power even 120 volt (say perhaps a Universal AC/DC Motor) let alone 48 volt devices........

I still vote YES its possible

John T
 
George - You are indeed correct about I squared R heating of the stator not being an issue!

My concern rather is the rotating field winding. Depending on the alternator electrical characteristics, the field could draw as much a 4x design current for the alternator to deliver 48 volts. And this would mean 16 TIMES the heat developed in the winding. Whether or not it would be a problem is uncertain.

As for where to find a 48 volt regulator, suggest paying a visit to your neighborhood electronics nut. If he's any good it should be a relatively simple matter for him to cob up a 48 volt PWM field control regulator.
 
From Wikipedia, the free encyclopedia
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Rotor (lower left) and stator (upper right) of an electric motor
Rotor from Hoover Dam generatorThe rotor is the non-stationary part of a rotary electric motor, electric generator or alternator, which rotates because the wires and magnetic field of the motor are arranged so that a torque is developed about the rotor's axis. In some designs, the rotor can act to serve as the motor's armature, across which the input voltage is supplied.

A rotor can act to serve as the motor's armature. Guess you can see how I got confused.
 
Oh, for gosh sakes, if you set up a conventional vehicle alternator up with a permag armature (rotor) the regulator in a conventional sense becomes a moot point!

(Cuz" the regulator normally controls current INTO the rotating field... permag field = NO wound rotating field = nothing for the conventional regulator to control.)
 
I have the booklet that describes the regulators.The devise you had contained a double pole double throw switch and an ac outlet.I have one under the bench.My 13v regulator had fewer parts.Simple to make.A heat sink, a power transistor and 6 other parts made a regulator.I used a 5hp briggs to spin the alternator.It was a heavy rig because you needed a 12 battery to supply rotor voltage.When the battery got low you threw the switch to charge.People are so used to mooching stuff for free they wont buy books now.Lindsay had booklets on running 3 phase motors on single phase power.Lead acid batteries,Making welders.I built a DC converter for my Lincoln 225 using information from the welder booklet.The Lejay manual is a good reference book even though it is dated.I bought a Lejay manual in the 50s.The Lejay Co sold aircraft generators and welders made from them.When Lindsay did a reprint I sold copies of it.I kept the last new copy I had.My old copy was well worn.To those who say it cant be done Ive all ready done it.There is a co making welders with alternators now.
 
No problem George, not to worry, youre doin fine, hope you get your charging system all figured out...

As always, fun sparky chattin with ya

John T
 
John Deere commercial mower has a 48 volt alternator to drive electric reel motors, but the regulator is in a computerized box.
 
BOB,
You are right. From what I've read, the wind generator's output if a function of it's RPM's. However, they are calling them 48 volt alternators. I'm going to guess the magnets are an energy saving device, so when there is no wind ther is no current drain.

Come to think of it, my old 1966 triumph 650 motor had a magnet connected to the crankshaft and the stationary coils around the magnet is where the induced voltage was made. So spinning a magnet really is a new thing. Back then, after the AC went throught the diodes, triumph used a zener diode as the voltage regulator, sending the excessive voltage to ground. Wind generators may be dumping their excessive voltage.

Everyone seems to be getting side tracked with terms and definations.

A friend wants a 48 v delco alternator to charge 4 12v batteries in series.

I need information on how to trick, modify, the voltage regulator to make 48v. So it seems everyone thinks it's possible, no one can tell me how to make it happen.

George
 
36 coupe,
I had a 1966 cuda. The voltage regulator was a single relay that would burn out in 10-12k. In the early 70's crysler used an external solid state reg which was a power transistor. I had to un-ground the one brush and send it to the collector of the NPN power transistor, emitter went to ground and the base voltage determined how hard the transistor conducted.

I'll google Lejay Co and see if there is something I can use.
Thanks,
George
 
(quoted from post at 08:26:02 06/04/13) BOB,
You are right. From what I've read, the wind generator's output if a function of it's RPM's. However, they are calling them 48 volt alternators. I'm going to guess the magnets are an energy saving device, so when there is no wind ther is no current drain.

Come to think of it, my old 1966 triumph 650 motor had a magnet connected to the crankshaft and the stationary coils around the magnet is where the induced voltage was made. So spinning a magnet really is a new thing. Back then, after the AC went throught the diodes, triumph used a zener diode as the voltage regulator, sending the excessive voltage to ground. Wind generators may be dumping their excessive voltage.

Everyone seems to be getting side tracked with terms and definations.

A friend wants a 48 v delco alternator to charge 4 12v batteries in series.

I need information on how to trick, modify, the voltage regulator to make 48v. So it seems everyone thinks it's possible, no one can tell me how to make it happen.

George
id you say which Delco alternator?
 
Yep my Mechanical Engineer Sparky friend, thats why in those small PM DC Motors if you reverse the polarity they (unlike a typical tractor electromagnetic field starter motor) spin the opposite direction. The PM has a fixed North/South magnetic polarity and a fixed field strength so you cant alter any current flow like on an electromagnetic field generator to increase the output. The faster the rotor spins the greater the output induced into the stator, so regulation has to be accomplished quite differently.

Very fun sparky chat yall

John T
 
I've still got a device, called "Tote-a-Volt"
that I connected to a 51 Chev pickup, then 65
IH Scout, that had a box with an outlet and a
switch. Throw the switch, a light came on when
engine was revved up to correct RPM,(Used hand
throttle) and I got 110 volt AC to run drill or
circle saw.
 



lets see.. a little of my electrical engineering...

take the voltage sense lead of the alternator and hook into a resistor tree on the top of the lowest resistor of 4 equal resistors arcross the output circuit. Make the 4 equal resistors very high in value so leakage current is not a problem. the 4 equal resistors will equal drop the voltage so that the sense lead reads 1/4 of the output voltage. That way the regulator will cut off only when the output is 4 times higher than what is on the sense lead or 4812. Or 12 * 4 = 48. (really its 14.2 * 4= 56.8volts). or simply order a 48 volt regulator used on railroad and other equipment.
 
(quoted from post at 09:20:23 06/04/13)


lets see.. a little of my electrical engineering...

take the voltage sense lead of the alternator and hook into a resistor tree on the top of the lowest resistor of 4 equal resistors arcross the output circuit. Make the 4 equal resistors very high in value so leakage current is not a problem. the 4 equal resistors will equal drop the voltage so that the sense lead reads 1/4 of the output voltage. That way the regulator will cut off only when the output is 4 times higher than what is on the sense lead or 4812. Or 12 * 4 = 48. (really its 14.2 * 4= 56.8volts). or simply order a 48 volt regulator used on railroad and other equipment.
ill, I have been thinking along those same lines & that is why I asked George whether he had specified which Delco alternator. You are clearly thinking 10SI & your plan may be OK, if the VR's PWM has the range to accommodate the 50 volt input from the diode trio & maintain appropriate field current. If it does not, then it may still work, by removing the trio & feeding the point of trio output with a 12v source (bottom battery). Don't go too high on the 4 resistor tree, as you don't want the nearly one milliamp drain of the #2 (sense) of the VR to alter to divider output. 10 milliamp tree should result in only small error or you can put pencil to paper and calculate error or 'tree' values for your 'error' of choice.
 
JMOR,
I was think of making a voltage divide to reduce the voltage. Say use a 30 ohm and a 10 ohm resistor. The divider would draw a little over 1 amp and I have power resistors that can handle that.

Problem, if we use a delco with a built in VR, where is the input to the VR? Are the two smaller wires on the alternator the input to the Voltage Reg? The one right goes directly to the +12v and the one on the left goes to the idiot light or to a diode?

So instead of giving the alternator full 12v on the right wire, run it to the voltage divider and give it 1/4 the volts? However the out wire of the alternator will be connected to 48 volts, so the voltage divider will still provide 12v. Do I have it right?

You mention something about watching the ma. Educate me, what are you talking about?

I think you send me a diagram, how to wire up a Massey generator, which by the way, I got working for a friend, Thanks.

Got a diagram of the delco alternator? Don"t really care which delco. Friend will want the one that has the largest amp rating.

Thanks,

George
 
(quoted from post at 13:37:22 06/04/13) JMOR,
I was think of making a voltage divide to reduce the voltage. Say use a 30 ohm and a 10 ohm resistor. The divider would draw a little over 1 amp and I have power resistors that can handle that.

Problem, if we use a delco with a built in VR, where is the input to the VR? Are the two smaller wires on the alternator the input to the Voltage Reg? The one right goes directly to the +12v and the one on the left goes to the idiot light or to a diode?

So instead of giving the alternator full 12v on the right wire, run it to the voltage divider and give it 1/4 the volts? However the out wire of the alternator will be connected to 48 volts, so the voltage divider will still provide 12v. Do I have it right?

You mention something about watching the ma. Educate me, what are you talking about?

I think you send me a diagram, how to wire up a Massey generator, which by the way, I got working for a friend, Thanks.

Got a diagram of the delco alternator? Don"t really care which delco. Friend will want the one that has the largest amp rating.

Thanks,

George
o need to burn that much power with 10 & 30 Ohms, as 1,000 and 3, 000 Ohms will be fine. And that takes into account the ~1ma Sense (#2) drain.

The two spade terminals are #1 excite and #2 Sense. Right & left depends on observer's and alternators positions.

If you do as I suggested in post responding to sotxbill, then there will be no connection to spade #1. That will be covered by the removal of diode trio and the addition of an input to the point of the trios previous output.

Sounds like the plan is wind power. If it is, I see a problem in that if batteries are low, calling for charge AND there is insufficient wind, then the bottom battery is still being drained by the VR's demand for field current & at 3 amps field, it will discharge in less than a day. Assuming 66 A-H battery.
10SI_48V.jpg
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10SI_rear_labeled.jpg
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JMOR,
THANK YOU. Actually the plan is not wind power. A friend, who I will not mention, he posts on here too, called me to do this. I had reservations as to if it will even work. He wants to use an engine/delco/4 12 batteries/48 volt dc motor to make a hybrid truck.

He was sure it would work. I saw this guy put a 5 hp briggs on top of an outboard gear drive. The outboard engine went bad. Not really sure if his air cooled outboard worked, but he has to get a red-neck award for trying the unusal.

Thanks Jessie for the diagram.
Let you know if he gets all the parts together and if it works. Looks easy to me with your diagram.
George
 
Lejay Co is long gone but still a good read if you can find the manual.I have the Chrysler relay in the shop and thers a transistor version out in the shed.I dont have the same interest I had 30 years ago.You could put new brushes in the early Chrysler alternator in a parking lot to get it charging again.
 
Dave, Thanks, I didn't know that. Bet the alternator off a JD would work better for making a hybrid truck. Bet it will cost a pant load.
George
 
Use a solid state regulator . Off the shelf for a couple of buck and handle 5-20 amps.
The voltage divider does not regulate and wastes power into heat.
 
Regulator does not step down 90V to 14.4V .
Regulator limits rotor excitation so the rectified AC from the stator for the desired 6,12,24,36 or 48V.
 
I know that a 24v Leece-Neville will do it. Reliably ? I dont know. I had replaced a alt(bad bearing) and put a rebuilt one on. Started the machine, checked voltage. 25ish at idle, 28 at high idle. Just as I finished putting my tools up, the operator came over and told me he had lost his computer, and two way radio. Since the alt was the last place I was I grabbed my meter, and nearly had a stoke. 48v at idle, I didnt have the nerve to check it at high idle. Luckily the machines inverter had low/high voltage protection, and shut its self off. I didnt hook anything up backwards or anything, I just figured someone in a volt reg factory somewhere either doubled up or halfed a diode or something.
 
You can connect a 36 volt zener in series with the sense terminal of the alternator.This is not the best way but it can be used to check the alternator's ability at 48 volts..
 
I know how zeners work, but not completely following your logic of using a 36v zener. How is that going to be better than using a voltage divider? I'm leaning toward adding a variable resistor or pot to fine tune with.

I'm not 100% certain this pipe dream, which isn't mine, will work without frying the exciter/armature/rotor/voltage reg, or the entire alternator.

Also been thinking of applying full 12v to alternator and controlling it with the RPM's of engine.
 
(quoted from post at 16:03:26 06/07/13) I know how zeners work, but not completely following your logic of using a 36v zener. How is that going to be better than using a voltage divider? I'm leaning toward adding a variable resistor or pot to fine tune with.

I'm not 100% certain this pipe dream, which isn't mine, will work without frying the exciter/armature/rotor/voltage reg, or the entire alternator.

Also been thinking of applying full 12v to alternator and controlling it with the RPM's of engine.
he problem with simply sticking a "36v zener" in series with the sense lead is that it will be 36v at a specific zener current & I will guarantee you that such zener current is not the less than 1 milliamp sense line current. So, to use such a zener, you now need additional resistors to establish the proper zener current & to what advantage?
 

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