63 volt 400 amp regulator for alternator

DMahalko

Joined Oct 5, 2008
189
Is it known what the amperage draw is, at cruising speed vs during moderate acceleration?


You may not require a huge charging current if the cruise power consumption is much lower than the acceleration consumption.

With a smaller charger, yes the batteries will discharge slightly while accelerating, but the batteries will then slowly recharge while at cruising speed.

Also, anytime you coast down a hill, or are braking, the output is basically zero watts so you get full current from the charger.



Why do you think you need 400 amps charging current at 64 volts, or 25600 watts?

The Comuta manual I found only talks about a 3.6 HP GE motor, and since 1 HP equals roughly 745 watts, the full motor output is apparently only about 2700 watts, about ten times less than your stated charger requirements.

But, the manual I found also only talks about 36v and 48v systems yet you apparently have 64v, so I have no idea.
 
Last edited:

akis02

Joined Apr 30, 2011
57
Wow, what an amazingly ugly mode of transport.

Google images, 1980 Comuta car:
https://www.google.com/search?q=1980+Comuta&tbm=isch


Why go through all this bother to make it into what will basically be an internal combustion powered vehicle.... except with additional energy-wasting conversion and storage steps, that will make it even more inefficient than a normal engine-powered vehicle?

Just buy an, um, normal car? A motorbike?
The was a BBC Top Gear episode where they mounted a small diesel engine onto an electric car - the diesel engine was charging the batteries while the vehicle was powered by the batteries - and that gave it a stupendous range. It would mean that the energy conversion from diesel to electricity to electrical motors and motion is more efficient than diesel motor to motion even though there is an extra step involved. Maybe the chemical energy provided by the batteries is the missing link, but it seems that the energy expended in manufacturing and servicing the batteries must account for more. Then there is manufacturing (energy) costs of a big powerful diesel engine against a much smaller diesel + energy costs of batteries. The manufacturing (energy) costs of retrieving large amounts of diesel to power a big diesel vs the costs of using a much smaller diesel fuel to power a much smaller diesel.

Hmm I do not know the answer, too complicated :)
 

strantor

Joined Oct 3, 2010
6,782
The was a BBC Top Gear episode where they mounted a small diesel engine onto an electric car - the diesel engine was charging the batteries while the vehicle was powered by the batteries - and that gave it a stupendous range. It would mean that the energy conversion from diesel to electricity to electrical motors and motion is more efficient than diesel motor to motion even though there is an extra step involved. Maybe the chemical energy provided by the batteries is the missing link, but it seems that the energy expended in manufacturing and servicing the batteries must account for more. Then there is manufacturing (energy) costs of a big powerful diesel engine against a much smaller diesel + energy costs of batteries. The manufacturing (energy) costs of retrieving large amounts of diesel to power a big diesel vs the costs of using a much smaller diesel fuel to power a much smaller diesel.

Hmm I do not know the answer, too complicated :)
Adding a conversion to a process, in and of itself, cannot make the process more efficient. However, if you greatly improve the efficiency of one of the conversions in the process, and at the same time add another conversion who's efficiency price is less than the gain it serves (does more good than harm) then I think you can improve the overall efficiency of the process by adding a conversion. This what I was talking about before. Consider the turbo.
The internal combustion engine is already very inefficient. typical car is maybe 15% efficient at pulling the energy out of gasoline and using it to drive down the road. Then figure how much is wasted sitting at stoplights, warming up in the morning, idling in parking lots, there is ZERO energy converted to work, all heat. When the car is driving, unless the driver is a drunk teenager or a nascar driver, the engine is likely operating significantly below it's powerband (usually when the pedal is floored, about 500-1000rpm before you have to change gears) so is thus even more inefficient than the quoted 15%. So maybe with idling, accelerating, piddling around below power band, etc. we're looking at 10%? (guess). Now, if we could increase the efficiency of the gas engine three-fold and reduce its size three-fold, then we should be burning much less gas. and we CAN do this, by running the engine constantly in its power band; a seemingly undersized generator running balls out constantly seems to fit the bill. The conversion loss from mechanical to electrical in a generator is very efficient compared to ICE efficiency, so it will be insignificant.
 

Thread Starter

raszpel

Joined Jan 9, 2012
27
DMahalko thank you for the links I already have a 20 amp 60v 120v charger that I use at home and when I can find a plug away. I would not need 5 alternators or at least I do not believe I will need 5 alternators. I want to do a proof of concept with probably a 100amp larger to see if it works. I might do a direct connect with a coupling eliminating the belt loss and slip potential.

Strantor I am not intending on wiring one or more alternators in series. I had planned on using a parallel configuration. If I use a belt configuration with more than one alternator. I would be using insulated mounting of some type. Or I will isolate the ground to case on the alternators and seperate it from the cases. I have seen multiple alternator setups for those super high end audio fold. So I know it can be done. But first I would like to prototype it with a proof of concept. I think I have a line on a 300amp 12v alternator that does not have a regulator. Hopefully the lower amp alternator will work and then I can try it with the higher amp unit.

I really appreciate all of your responses, just please no haters, If you have a lot more money than I do, do not flaunt it. This is within my financial capacities.

Does anyone know why I keep getting the line at the end of some responses. I will not receive any more emails until I log on?
 

Thread Starter

raszpel

Joined Jan 9, 2012
27
DMahalko my Commuta has a 6 hp motor upgrade running at 60v. I have asked other members of the Citi-Car groups and average cruising amps are around 120amps to 140amps at 45mph. With peaks over 250amps some up to 300 amps when hill climbing and accelerating. I selected 64v for the charger because as I understand. I will need a higher voltage than 60v when pushing the charge back into the pack. I do like how you explained some of what I am hoping to be able to do with the portable charging system very clearly. In reference to extending the driving range of the car.

Stantor you hit the nail on the head with the fuel engine running at the peak efficienty rpm. The generator will be a positive factor on transportation cost. Granted not as inexpensive as an electric outlet but much more efficient that almost all sub B size compacts. Combine the ability to drive most of the way on the charged pack with the very efficient small high RPM direct coupled generator. I believe it could help a lot of home built small Electric Vehicles over come the biggest problem distance anxiety, being stranded.

I am looking around to see I should have an old alternator around to get the measurements of. I am very good at soldering and following schematics or at least a skilled hobbier. What and how are the measurements that were needed to design the regulator. I do like the ability to adjust it by switching resistors in and out of the comparator circuit portion.
 

DMahalko

Joined Oct 5, 2008
189
Either my math is wrong or something else is severely increasing the motor load.

  • 6 HP electric motor * 745 watts per HP = 4470 watts

  • 4470 w / 63 v = 70.9 amps


Though there are a number of possibilities.

  • You can run a motor at higher torque than what is rated, though with risk of burning up the windings from excessive heat. Perhaps with a motor exposed to the road under the car body, that provides sufficient forced-air cooling while moving forward, to tolerate 6+ HP operation.
(Still, 120 amps @ 63v suggests to me 9-10 HP and 150 amps @ 63v suggests 12-14 HP. Seems unpossible for continuous operation.)

  • 745 watts per hp is an efficiency figure based on an ideal motor design. The motor used in this vehicle may have a less than optimal design that wastes some input energy. Though wasting up to 50% of the input at 6 HP sounds odd.
Once again I just have to say "unknown, insufficient data".


63-64 v does appear to be the correct charging voltage, if you have 10 6-volt batteries. Since the actual 100% charge voltage of a single lead-acid cell is 2.1 volts, and a 6-volt battery contains 3 cells: 2.1 v * 60 cells = 63v
 

Thread Starter

raszpel

Joined Jan 9, 2012
27
You are right I am not expecting continuous operation at that level. I will mostly be traveling side roads with 35mph limits. I am not sure of the efficiency of my motor. I purchased this vehicle from a man who used it daily to drive around Santa Cruz (in town). He did not take it on trip longer than 20 miles round trip.

Your math I think is correct the amp figures are what several of these car owners with amp meters have reported. They all said around the same figures. they did mention that in town up to 35mph figures similar to yours. But when the speed increases the load increases.

From your figures and others responses, I may be able to use a lower amp output that I had originally thought. I am hoping to get a 300 amp alt with a bad regulator for a very reasonable price. I should know by tomorrow late afternoon if I can get it reasonably. If I do when I receive it I will take the measurements needed. All of your input is making this concept appear more feasible for these vehicles and other home build lower volt EV's. My impression is if I were to end up with a 150amp 64v charging/ supplement system, it's duty cycle would not have to be very high to maintain my pack. Any ideas on this?
 

strantor

Joined Oct 3, 2010
6,782
It's fairly common to "over amp" traction motors in EVs. The main limiting factor in electric motor power is the ability to cope with heat. The HP/KW rating is based on the max amount of amps that can be maintained continuously in still air without resulting in thermal runaway. The rating does not necessarily reflect the amount of amps it is possible to pass through the motor without fusing the windings.

Take for example, the motor on my workbench right now, the ME0708. it is rated at 4.8KW. Most motor manufacturers would just stop there, but since it is a traction motor and the manufacturer knows that the user will be over-amping it, this particular manufacturer has provided us with an additional rating: 15KW for one minute. I have heard reports of some users actually taking this motor much higher than 15KW, up to 30KW, for brief periods, like a drag race. And this is a permanent magnet motor which is "sensitive" in that if it gets too hot, the magnets demagnetize and the motor is ruined. Users of wound motors can get away with even more abuse. Take a look at what guys are doing in electric drag racing circles. I've seen people using 25hp motors make a full sized car go down the track faster than a 500hp ICE counterpart.
 

strantor

Joined Oct 3, 2010
6,782
OK here's another idea. This idea doesn't make use of the ICE power band efficiency, but it does get you on the road sooner and cheaper.

The lawn mower motor does not necessarily need to provide electrical assistance, in order to contribute to the process. It could provide mechanical assistance. If instead of dragging your trailer, if your trailer was pushing was pushing you down the road, it would alleviate a great deal of work to be done by the electric motor, and thus extend your range considerably.

Just replace your trailer axle with a car differential (angled upward) and mount your lawn mower engine to it. You would need some kind of speed control, and the engine won't go down to low RPM. I'm thinking a clutch to be released at low RPM, and an accelerator setpoint to come from the accelerator pedal.
 

Thread Starter

raszpel

Joined Jan 9, 2012
27
I have seen pusher trailers on the web and they look interesting. The ones I have seen used automatic transmission let in gear. When the motor is turned on and the rpm are increased the system pushes the vehicle. When the motor is turned off the trailer just free wheels. I had not though about make a small pusher out of the lawn mower engine, now that is an idea I could do. Not as nifty as the gen-set but definitely do able. thanks for the Idea. I will be thinking about that one. I still want to build the gen-set but might start with a pusher hummmm.
 

strantor

Joined Oct 3, 2010
6,782
I have seen pusher trailers on the web and they look interesting. The ones I have seen used automatic transmission let in gear. When the motor is turned on and the rpm are increased the system pushes the vehicle. When the motor is turned off the trailer just free wheels. I had not though about make a small pusher out of the lawn mower engine, now that is an idea I could do. Not as nifty as the gen-set but definitely do able. thanks for the Idea. I will be thinking about that one. I still want to build the gen-set but might start with a pusher hummmm.
What? you mean it's already been done before? sheesh.

This is how I know when I've had a good "revolutionary" idea - I find out it's not revolutionary and people have been doing it for years.
 

Thread Starter

raszpel

Joined Jan 9, 2012
27
Ok I just won a 300 amp IRAGGI alternator on EBay check out this link.

http://www.ebay.com/itm/320981801145?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649

My cost including shipping is $142.50 which I think is a good deal for me. The listing claims it still charges but the regulator is bad. I am confused but I took that to mean the windings and such are good just the regulator is not working at the right voltage. It looks like the perfect donor builder for my project. I have already paid for it so it should be shipping in the next day or two. When I receive it I will let you all know. Then I can with get the measurements strantor said were needed to design the regulator. I am hoping that the regulator design can with minimum modification work on different alternators. This would make it of a greater value to the open source EV community. Like I said I want one for me. Plus I would like to be the test bed to get some more open source circuits for EV home builders like myself and friends at college.
 

DMahalko

Joined Oct 5, 2008
189
I still don't know what you are expecting to do here. The output of a 12v alternator is probably going to be no more than about 15 volts or so.

One 12v alternator by itself will do nothing useful to a 63v battery pack.

An alternator regulator mainly just turns the output off when the batteries are charged. It does not step the voltage up or down.

Options are:
* use five 200A 12v alternators and regulators wired in series, to reach 60+ volts output at 200A

* use an expensive custom DC/DC converter to step from 12v to 64v
 

Thread Starter

raszpel

Joined Jan 9, 2012
27
I have ready in many and I mean has to be close to 100 places on the internet and in books about getting up to 120v AC out of automotive alternators. This is done by removing or bypassing the regulator and feed full current and voltage into the armature. Here is a link to one being used for 120v AC.

http://www.youtube.com/watch?v=aY9qmeA8gVI&feature=related

I know the amperage will drop that is why I am going to start with a 300 amp alternator.
Hopefully I will have close to 100amp when it is at 64 volts. I do not know the formula to calculate this number. But what-ever it does work out to be will be a big plus to me for my uses. My motor is not rated for more than 30 minutes continuous duty at the higher speed. I plan on using a lot of side roads. Heck I have used them before when my car had front end problems and shook way to hard at 55mph. I have read of up to 130v AC but that leaves pretty much no usable amperage. I might have to use 2 alternators but I am hoping that one big one will render a usable system. Maybe not my Ideal system but one to start using and improve upon like all home_build (DYI)'s do.

I have seen forums about just this only using more expensive commercially manufactured generators with more weight. I hope this can be accomplished in under 200 lbs. I have been researching and I think I may make a single swivel wheel trailer for this system. It would be easier to streamline. The single wheel would also reduce the drag and weight of the trailer. Along with the single wheel design will make maneuvering it in town and such easier, like backing up and parallel parking.
 

strantor

Joined Oct 3, 2010
6,782
I have ready in many and I mean has to be close to 100 places on the internet and in books about getting up to 120v AC out of automotive alternators. This is done by removing or bypassing the regulator and feed full current and voltage into the armature. Here is a link to one being used for 120v AC.

http://www.youtube.com/watch?v=aY9qmeA8gVI&feature=related
I suspect you're right, but the link is not a good example of what you describe. In that video, the (unaltered) alternator is only generating 12VDC. The "1800W xantrex prosine inverter" is taking the 12VDC and turning it into 120VAC.
 

cork_ie

Joined Oct 8, 2011
428
I have ready in many and I mean has to be close to 100 places on the internet and in books about getting up to 120v AC out of automotive alternators. This is done by removing or bypassing the regulator and feed full current and voltage into the armature. Here is a link to one being used for 120v AC.
I have also pointed this out to you already. You will not get 63V or anything like it out of a standard 12Volt alternator.

Absolute max voltage will be about 30V and that at 6,000 RPM. You would need to rewind the stator winding (lighter wire with more turns/pole) to get higher voltage.

If you try feeding 63V into your rotor (armature) instead of the normal rotor current of about 3 or 4 Amp it will increase to about 18-20 Amp. 20 Amp@63V≈1200 Watt= fried rotor winding.
 

strantor

Joined Oct 3, 2010
6,782
I have also pointed this out to you already. You will not get 63V or anything like it out of a standard 12Volt alternator.

Absolute max voltage will be about 30V and that at 6,000 RPM. You would need to rewind the stator winding (lighter wire with more turns/pole) to get higher voltage.

If you try feeding 63V into your rotor (armature) instead of the normal rotor current of about 3 or 4 Amp it will increase to about 18-20 Amp. 20 Amp@63V≈1200 Watt= fried rotor winding.
Either you've done a reversal of stance or I'm grossly misunderstanding your post #7. I thought you were just waiting for him to measure and give you the rotor current and inductance of his alternator, then you had a circuit in mind to get 63V out of the alternator. where did I miss something?
 

cork_ie

Joined Oct 8, 2011
428
Either you've done a reversal of stance or I'm grossly misunderstanding your post #7. I thought you were just waiting for him to measure and give you the rotor current and inductance of his alternator, then you had a circuit in mind to get 63V out of the alternator. where did I miss something?
What I said in post #7 is
"The stator output current will not be directly controlled by the voltage regulator but will be a function of the rotor field strength, the speed of rotation, the stator size, the ability of the rectifier to handle your peak current, and of course the ability of the batteries to take the current at a particular voltage difference between the alternator output and the battery nominal voltage.

You need to check all the other parameters first, cooling of the rectifier being especially important - you will need to dissipate nearly 650 WATT at peak output!!!!
After that the voltage regulator is the easy bit.
I will first need to know your rotor current and an approximate idea of it's inductance. "


He mentioned using a 24V 400A oil cooled alternator. He was initially looking for a regulator design and that is why I wanted the rotor parameters. With a push he might be able to get this up to 63V.
I pointed out to him in a later post that he hadn't a ghost of a chance with standard 12V units.
 

Thread Starter

raszpel

Joined Jan 9, 2012
27
I hear what you are saying. Here is another site I have seen referenced many times. About a third of the way down the page. There is material about using a car alternator to produce 120 volts dc not using a voltage inverter. The 120v is produced using the alternating current produced by the alternator using a homemade rectifier circuit. I could copy and paste a ton of links but it would waste everyone's time, and maybe even bother some here. I respect the beauty of this being an open forum, and know what it is like to get my email filled with a bunch of banter.

When I get the 300amp unit in I will take some measurements as suggested. I do appreciate your thoughts either pro or con. I am I am sure others can and are learning from everything posted.

Let me explain a little about myself. I used to design hardware and software starting back in the late 70's. Until an accident back in the early 2000's caused a massive and extensive brain injury leaving me brain dead. Now here is the plug for organ donation. I am a organ donor so they kept my organs fresh. From what I am told 15 to 30 seconds before cutting me open my brain partially restarted. Prior to that it was not doing anything on an EEG. ( I am alive because I was willing to give someone else the gift of live or quality of life, Be an organ and blood donor. From this I have partial memory just enough to be dangerous and frustrated of electronics and even less of software programming. I still have my soldering skills. I know what all the parts are but for the life of me can not design or debug anything, no matter how hard I try.

Not looking for sympathy here, I am fine, just hindered a bit. So when I talk like I know but not really that is the truth. Formulas, etc all are not able to be relearned for some reason. With that said you can understand how any input on this or other subjects is all good to me, even if you say I am an idiot, hay maybe that true( although no one has typed it yet. Which shows the high caliber of the members of this forum.)
Again thanks everyone for all the input, keep it flowing. :)
 
I don't disagree with any of the above comments RE efficiency of the finished system but for the record and if you are serious ...

Use a permanent magnet alternator, because they are the most efficient way to generate power, if not the most convenient.
Since you will only want to charge the battery if it is low you don't need to worry about long periods of tempered charging.

That brings you to the power plant ... think all or nothing, well mostly.
Size the alternator to deliver the maximum charging current and voltage at the most economical speed and power output of the engine.

All you need to do then is speed up or slow down the engine, within the maximum efficiency band to control the voltage.

No switching losses, no complexity and if the battery/car cant accept the current for a significant period, requiring your charging engine to dramatically slow and get inefficient, then stop it - until you can accept the charge.

You could even let it run whilst you are in class, so you have a bulk charge to get home.

Out of the box I know, but the thread was looking a little out there anyway.
(Sorry)
 
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