Need generator information

[Projector]

Hi, new member here.  I was looking for information on generators, and this board keeps coming up.  After reading some of the posts here I think I might be able to find my answer.  I do like what I've seen so far though, looks like I'll be able to make use of some expertise here to add a backup generator to my current house, and later build an offgrid place.  But for now...

I am working on an electric vehicle conversion, in stages.  The current stage is going to be moving all accessories to a bed mounted shelf and off the current ICE engine.  The problem I'm having is locating an alternator that can produce approximately 6000 watts at 120V.  I can come up with a 12V that will do the job but this would require a transformer to get the voltage where I need it.  I'd prefer to have a direct drive to simplify the project.  The AC compressor, 12V alternator and power steering pump will be driven by a 3-5HP 120V motor in the bed.  The only things that will be driven by the engine when this is complete is the water pump and the alternator used to power the accessories.

I have found a couple of possibilities, there is a company overseas that makes 220V alternators for emergency vehicles that will fit under the hood, but I'd rather deal with a supplier in the US.  Another alternative is a Northern Tool generator head but this requires the generator to be spun at least 3500RPM.  I can get there, but the generator would potentially see 40K RPM in occasional bursts.  I don't think this will do the trick even though it will bolt up.

Can anyone recommend a place I can check to find an alternator that can produce the power I need at 120V?  I've been looking for about a month now with little luck beyond the foreign supplier.  Thanks.

[JW]

Hi Projector,

" The problem I'm having is locating an alternator that can produce approximately 6000 watts at 120V.  "

"I can come up with a 12V that will do the job but this would require a transformer to get the voltage where I need it."

Uhuuu'hu....

"The AC compressor, 12V alternator and power steering pump will be driven by a 3-5HP 120V motor in the bed."

Im, guessing, these will be, -those have-to-have aux systems.

"But for now...

I am working on an electric vehicle conversion, in stages."

ummm-hummmm.

"Another alternative is a Northern Tool generator head but this requires the generator to be spun at least 3500RPM."

Now look-here,

 I actually have one of these, its rated at 8kw 120/240 60HZ VAC. If you would like I can post a picture. Its just laying around in the shop.

Not to be dis-encouraging, Projector,

 " I can get there, but the generator would potentially see 40K RPM in occasional bursts.  I don't think this will do the trick even though it will bolt up."

Why is that?

 The rotor on such a genny has some weight to it. RPM & TORQUE = H0RSEPOWER, like volts x's amps = watts.

What exactly are you planning to spin with? A tesla turbine?

Im just wondering, are you going to use a gear-drive from the main unit to run the auxillary's in the truck bed.

:0

JW

[zeusmorg]

You're moving these components out of the engine compartment and back to the bed? Sounds like you're incurring extra costs that aren't going to be needed in your long term project.  Re-routing hoses, making special lengths, discharging and then re-charging your a/c system.

Why would you generate 120v ac to drive a motor to run a 12v dc alternator? Double mechanical conversion,, big waste. Most final conversions use a step down electrical converter to get their 12v dc.

How are you planning on running those units in your final conversion? Most people leave the ancillary driven units in the engine compartment. Driven off the main electric motor.  I guess you also realize that a/c will eat a lot of your battery capacity up. Surely you don't plan on running an alternator of any kind in your final setup?

 I know you're attempting to create a more energy efficient vehicle, I'd hate to see how much your fuel mileage drops after this step in the conversion.

[Projector]

To answer the questions:

JW -   The accessories are must-haves as I'm not the only one that rides in or drives the truck.  I live in Oklahoma and it gets pretty hot in the winter, and while manual steering holds no problems for me I don't want to subject the wife to it.  

I intend to drive the high power alternator with the current engine in the truck, and drive the accessories with a separate motor in the bed, with power being transferred via electrical wiring.  

On the potential 40K RPM on the Northern Tools generator, I intend to drive it off the engine currently in the truck.  This means I need around a 6.7 to 1 pulley ratio to provide the minimum 3500 RPM to the alt/gen at engine idle of 525 RPM.  525 x 6.7 = 3518.  Thie means at engine redline, 6000 x 6.7 = 42.2K RPM.  No idea if the generator would be able to provide enough power with a lower ratio at idle, or if it can handle a variable RPM input.  Pics would be appreciated, along with something of a known size for reference.

Zeusmorg -Moving the accessories isn't that big a deal to me.  I also want to transfer weight to the rear of the vehicle for better traction as trucks are very light in the back.  

On the running of a 12V alternator in the bed:  I didn't even consider taking a tap off the engine generator and converting it to 12V use, thanks for the idea.  This means I'd still need the same size alt, but a smaller motor would serve to run the accessories since now I'd just have to drive the PS pump and AC.  Outstanding!  

In the final iteration, I hope to just move the wiring from the high voltage alternator to the final drive's power supply, which is looking like will be a diesel electric generator setup.  

I'm hoping that the lost load from not driving the other accessories will make up for most, if not all of the extra load the new alt puts on the engine

This gets me back to the original question of finding an alternator that can produce 6000W at preferably 120V that can also provide the power on an engine with variable RPM.  

[Projector]

Just caught the typo right after posting, meant to say hot in the summer, not hot in the winter.  Heh heh heh...

[JW]

OK,ok

 Finally stops sratching head.

Projector,

" Pics would be appreciated, along with something of a known size for reference."

 I can do that.

JW

[zeusmorg]

 You may look into an electric power steering pump, as i remember subaru made one that was 12v dc. What i liked about it was that it was speed controlled, in other words it ran higher at low speeds or stopped and shut down completely at speeds over 25 mph.

 Much more energy efficient than having a belt driven unit especially on an all electric car. The biggest problem in energy waste in a PS pump is that it needs to be oversized for the job since you need it most at idle and stopped.

 The weight you're moving will be negligible compared to your final battery pack.

[Projector]

Thanks for the pics.  Unfortunately, nothing here is of much use towards my original design other than the suggestion about taking a tap off the power generator to run the 12V instead of running a separate 12V alternator.  That was a great help as it reduces the size of the motor I need to run.  I've also investigated picking up a window unit HVAC system to tear apart and use the compressor to operate the AC, but hadn't turned anything I liked up on that.  Think I'll have to give it another go.

The electric power steering pumps, at least for the Fiero, were problematic which is why I discarded them.  I'll have to look at the Subaru model.  I'm planning a rack and pinion conversion, and I'm pretty sure the Subarus use R&P steering, so it would be a good fit.  Just not sure if it could handle a hydroboost brake setup, which was another planned upgrade.  This will take some thought as a hydroboost unit takes up a lot less space than a vacuum boost unit.  Hydroboost would require the PS unit be on at all times.

Again, I appreciate the help, I'll keep checking back to this thread for a bit to see if there's any new information.  Guess it's back to the 'ol drawing board here, but I have more to consider now.

[Boss]

I hope to build an electric vehicle after I get my wind turbine up. Your hassles with the accessories reaffirms that I won't put any thing extra on mine. Way too much trouble. My EV will stay on the ranch, I'm thinking of converting a small 4x4 pick up , or perhaps a 4x4 ATV if I can pull a small trailer full of batteries

 

[Projector]

http://www.americanarmature.com/images/Alternator%20Spec%20500.pdf

WOO HOO look hard and long enough and there's always a solution.  500 amp alternator at 28V, that's 100 amps at 120V, give or take rectification losses.  24 pounds, and operates at normal engine RPMs with most power available by 900RPM.  This and a deep cycle Optima is my solution.  This is more than enough juice to power anything I want in a single unit.  

Brian, instead of dragging a battery pack I invite you to consider two other options; one is to mount a small generator in the bed of the truck, the other is to mount a generator on a trailer.  The genset in the bed will reduce bed capacity and require that you carry the weight at all times, but not only eliminates the need to drag a trailer, it allows you to pull a trailer not dedictated to providing vehicle power.  The genset on a trailer would only be used and carried when needed and allows full use of the bed, but won't allow you to pull anything else.  Either way, with a generator instead of batteries you have a lot less weight to move, and unlimited mobility.  You'd need a couple of tons of batteries to get any worthwhile range, would need to maintain the battery power level even when not in use to extend their life, would have to deal with disposal and replacement when they went bad, and would have to have an electric motor powerful enough to pull them, which eats into the range.  A decent genset will only weigh in at about 300-400lbs, and some of them will carry half load on a gallon or less per hour.

This is the solution I plan on, will be pulling the engine and transmission and replacing them with a generator powered by a small turbodiesel built to run most efficiently at the RPM required by the generator head unit's most efficient speed.  For a motor I'm currently considering one of the Warp/Transwarp family.  If you want to look do a search on transwarp 13.  Ideally, and I'm hoping I can find one when the time comes, is an AC traction motor which is more powerful and far more efficient than a brushed DC motor.  AC traction motors are what locomotives use, and as I understand it there are companies developing them for the automotive markets.

[JW]

"My EV will stay on the ranch, I'm thinking of converting a small 4x4 pick up , or perhaps a 4x4 ATV if I can pull a small trailer full of batteries- Brian Rodgers"

Ahhhh, yes

You must be new (a newbie) to the internet.... Trust me you can expect 'your name' to show up on 'your cat "googling up a fur-ball"

But anyhow, glad you chimed-in.

 Actually, and this is how "projector" got me thinking (trust me I hate it when it happens) He's stuck on this # of 6kw for the aux-systems, when im thinking "a good starting point for a GEO METRO conversion- is like 30kw"

 Then to complicate things more, there's a 5-to1 gear-ratio involved, well, that, isnt going to make $#|+, at idle engine speeds?

Soooo, basically, I figured it is some sort of hybred design.

-NEVER-THE-LESS-

One does not need a wagon-lode of batterys for an electric vehicle. For example, take a look at the latest electric 1/4-mile electric race bikes. Seems to me, the actual weight to power ratio, is like insane.... But the range is short.

   But seriously, one can only do this, with a DC type of traction motor. This is what threw me for a loop. Almost all cutting-edge design electric vehicles from the big OEM's are based on AC type traction motors.

Believe it or not, there are a couple user's here that have sucessfully built EV's, Rich and Jerry come to mind. But anyhow , you never know.

  Personally I like the idea of a 4wd EV, you know what they say about electric motor's, they make max-torque at start-up.

"AC traction motors are what locomotives use, and as I understand it there are companies developing them for the automotive markets.- projector"

I think they use them because the motors dont get much hotter than 220*f running with AC.

JW

[Projector]

I'm stuck on 6kW only because of the size motor I need to run the accessories.  I was figuring that the motor to drive the accessory package would need to be about 5HP, which works out to about 3500 watts of power needed.  A 6000 watt alt/gen would be able to run this at half load, which would be easy on the generator.  Taking the 12V alternator out of the mix and using the 6kW generator to provide it directly means I can use a smaller motor to drive the remaining accessories, but I'll still need the energy to provide 12V for the rest of the vehicle.  

" Then to complicate things more, there's a 5-to1 gear-ratio involved, well, that, isnt going to make $#|+, at idle engine speeds?

Soooo, basically, I figured it is some sort of hybred design."

Huh?  No idea what you are talking about here.  I don't think you understand what I'm aiming at on this.  All I'm working on is making all the accessories electrically driven, not a hybrid drive.  There will be no electric motor in the driveline at this time.  So far as the gear ratio you speak, all engines in production today use a gear ratio adjustment to change the speed of the accessories in relation to engine RPM.  Crank pulleys are 7-9 inches in diameter, alt pulleys are normally 1.5-3.5 inches in diameter, which means the alternator spins faster than the engine.

[JW]

Hi Projector,

"I was figuring that the motor to drive the accessory package would need to be about 5HP, which works out to about 3500 watts of power needed.  A 6000 watt alt/gen would be able to run this at half load,"

Although, what you say there, maybe essentially correct. IT's wrong and thats not the way things are done.  

 For example- you have '0' reserve capacity built into the system. I dont care what you say, the alternator in my ford truck does-not, (in fact), spin at 40k rpm... under 5000 rpm being driven by the crankshaft pully, period. Trust me, at such actual speeds it would be more dangerious than spinning a tapered roller bearing cage with an air-blower nozzle from an air compressor.

Uknow I was thinking about Brian today, I can see how my remark about not needing a wagonfull of battery's behind an EV, could be mis- advised. Nevertheless one must be somewhat 'thick-skined' around here. bla,bla, blaaa anyway, I can imagion that theres not much space on a 4wheeler ATV, for battery's. Brians statment does make sence in the regard to the suggestion...

JW

[jonas302]

if your going to run a gen set to power the trucks electric motor why wouldn't you belt drive the assesorys?running a engine  making electricity to drive a motor to drive engine parts mot only wastes fuel  but adds weight that all electric cars are trying hard to get rid of

[Projector]

I don't see how you figure that my calculations are incorrect.  Point blank, if the crank pulley is X number of inches in diameter and the alt pulley is Y number of inches in diameter, there is an multiplying increase in alternator speed according to crank speed based on the ratio between pulley diameters.  If you have a 10 inch pulley on the crank and a 1 inch pulley on the alt, the alt has to spin over 10 times for each revolution of the crank.  That's just how it works.  In order to get the one generator that requires a minimum speed of 3500RPM to spin that fast at an idle speed of 525RPM, the generator would be spinning at 40K RPM if the engine spins up to 6K RPM.  Period.  Math is one of the few things you can't argue with.  On your own truck, assuming a drive pulley of 7.5 inches and a driven pulley of 2.5 inches, you'd be looking at an idle alternator RPM of 1575RPM if your idle is 525RPM, and a max engine speed of 6000RPM would be a max alt speed of 18,000RPM. The alternator can handle such speeds for the very short time you spend at max engine RPM, but I don't think one would like 40K for any amount of time, which is where the problem with that one generator comes in.  This is why I posted a question here to begin with, to find out what kind of power curve the generator from Northern Tools shows so I could see if there was a way to make it work.   Obviously, if it has to be able to spin up to 40K it isn't going to work out, nor is it going to if it won't make an appreciable amount of power below 3500RPM.

I also don't see where I have no reserve capacity built in if the generator can make half or better of the power needed to run the motor.  I don't have a modern truck with 120 amps of electronics needing power.  The most my truck pulls is 70 amps at 12 volts with the electric fan on full out.  That means 840 watts, plus the 2220 watts a 3HP motor would require means I'd have about 3060 watts required, give or take.  That means I'd be loading the generator up to half its rated power output.  Even if I did need 120 amps for just the truck's operation, that's only 1440 volts for a total needed power of 3640RPM.

No matter on the above though, it's no longer an issue.  Good news is, I may be on to a better solution, found a company that sells mobile refrigeration products that operate at 12V.  Some of their compressors are designed to operate refrigerated food delivery trucks, amongst other things.  I'm rounding up information with them now on a couple of their compressors, looks like they have a couple of hermetic units designed for mobile applications that can do the job with a max input power of 168 watts.  And, it comes with a controller that allows it to run longer at a slower speed rather than run fast and cycle more, for smoother operation and a lower max power requirement.  I assume you'd accept their power requirements as accurate seeing as they make a living selling these things?  One of these compressors would eliminate most of my power load, and require that I only come up with a way to run power steering.  This one looks to be the hard one, but if I have to slap a motor on the existing pump it should just need a 1HP motor.

[JW]

I like your style Projector....

 Clearly, you have a well thought out reply there. Actualy I would compare it to something like Flux would respond.

But honestly, the idea of my alternator spinning 18k or so, scares the hell out of me.

 I was messing around with some pelter-juctions today, without heat sink's , didnt see much of a temperature differental. Refrigeration is a hot topic for the remote living section. Im going to have to spend sometime mounting heatsinks to get better results with these.

Heatpumps of anytype are interesting to me.

JW

[JW]

I was just laying in bed thinking about this 18k rpm alternator business. And something just struck me.

When I size matched v-belts between 2 pulleys at a distance. I measure 1/2 the 'perimeter' of each pully then add that x's the distance to each halfway-point of distance between the pulleys by 2. This enables me to calculate the diameter of the needed belt, to within a 'ballpark range' of +-1 inch. Generally, this equals about a 1/4 in of slide adjustment capacity, on either pulley.

If I have a 3in diameter pulley its parimeter is so many inches long. If I have a 9 inch diameter pulley its parimeter is so many inchs. Is the ratio between the pulleys, 3 to 1 when measured this way?

It was always my understanding, an auto alternator had a best gain of 1000rpm over the crankshaft speed. This works out to less than 2 to 1. But I could be wrong, just thinking.

JW

[Projector]

The easiest way to think about pulley ratios is to think of them as they are rolling.  A 9 inch pulley has a circumference of 28.2744 inches, meaning that for it to roll over once it will travel 28.2744 inches.  A 3 inch pulley has a circumference of 9.4248 inches, so it will travel 9.4248 inches in a single revolution.  If you roll them side by side, for the 3 inch pulley to travel 28.2744 inches, it will have to spin over 9.4248 x 3 inches, or 28.2744 inches.  The belt only comes into contact with the pulley over a small part, but when the 9 inch pulley spins over once it will still move the belt 28.2744 inches, and will pull the 3 inch pulley around 3 times in the same amount of time.  The only way the alternator would have a fixed RPM increase over engine speed and not a multiplicative increase is if the belt were slipping on the alternator, or if there were some sort of continuously variable transmission-like assembly between the alt and crank.  

On the generator spinning over 40K RPM, we both agree this is a problem but I don't think it's understood WHY it's a problem, and this is because while I've got a wealth of knowledge on automotive systems as they are, I've got a lot to learn about generators.  The specs on the Northern Tools generator says it needs a minimum of 3500RPM.  BASED ON THIS, I figured out the pulley size requirements that will allow an engine AT AN IDLE SPEED OF 525RPM to spin the generator at 3500RPM.  Unfortunately, this also means that as the engine has a redline of 6000RPM, that the generator will be spinning in the neighborhood of 40K RPM.  I also understand that your Ford's alternator doesn't ever spin up to 40K unless you have a stick shift, run up to about 140MPH then jam it into 1st and pop the clutch.  This would get it up to 40K RPM for about half a second, before the engine and alternator both detonate.  You probably have a 7 to 8 inch crank pulley and a 2-3 inch alt pulley, so your alt will spin at 18KRPM at redline only.  Normally your alt is going to spin at engine RPM times crank pulley diameter divided by alternator diameter, so at 2000RPM with an 8 inch crank pulley and a 2 inch alternator pulley, the alt will be spinning at 8000RPM when cruising on the highway, and 2400 RPM at an idle speed of 600 RPM.  I hope this clarifies my comments.  

That's a nice method for calculating V belt diameters, too bad there's no simple way to calculate serpentine belt diameters.  Last time I had to find the size for a custom setup it meant a lot of trips to the parts store.  Got to where they told me to just go find what I need and when I got the right one bring it back and pay for it.

[Projector]

"I like your style Projector....

 Clearly, you have a well thought out reply there. "

Heh heh.. thanks.  

Peltiers don't seem like that good a solution to anything to me as they really don't generate that cooling power, especially when you take costs into account.  There's a great many other ways to accomplish the same task for a lot less.  Still, if nobody ever messed about with stuff we'd all still be sitting around wondering if rocks were edible. 8^)

For refrigeration purposes you might look into those Danfoss compressors that I'm looking at, I've been going over their site and they have a great many sizes and efficiencies there.  Some are even rated to work directly off solar cells.  They have tons and tons of information about their compressor specs, unfortunately I'm also not a refrigerant tech so I'm not able to understand them.  Unfortunately I've not gotten a reply on the board I posted to about them, going to the horse's mouth today.

[JW]

Your doing fine, dont worry about that. Believe it or not, you may be the only one working on such a thing. That's not bad...

JW