Micro CoGen.

I would encourage you to look at serpentine pulleys, often called micro groove.  The initial cost is more than cheap aluminum Vee pulleys, butthat they will pay for themselves if you use the system a lot in fuel savings alone. Not to mention they last forever.

I got mine at Utterpower.com. Great quality and fast service.  http://www.utterpower.com/products/pulley/

On the motor, if your gen set still works, I would sell it whole and buy a 13-14 hp engine with a non tampered shaft. it's my fear you will spend more time and money getting a pulley for that tampered shaft than what you would spend on a proper engine.

Thanks to all

Quote from: Ronmar on October 18, 2012, 10:32:16 PM
That is an interesting idea Lloyd.  For that matter, PW is PW and you could use a single channel charge controller.  A sensor looking at the field drive of an alternator could sense the duty cycle of the PWM driving the alternator and could drive a throttle servo that actuates the engine governed speed control lever.  A PWM servo may even be an off the shelf item, but there would be no delay between throttle and field control, so the linkage to the servo would have to be setup so the engine power curve is always ahead of the alternator load.  But you might be able to make it span a larger RPM range more easilly like the honda EU sets do, from high idle to full rpm based on load...  You might have difficulty configuring it for short transient loads, unless you can program a delay into the controller...  Interesting idea...

VW, you basically control amperage with voltage and I guess vis versa.  When charging a battery, the greater the alternator voltage in relation to the battery voltage, the greater the current flow into the battery.  So a typical auto alternator control looks at the battery voltage and adjusts the field to deliver a particular output voltage at the battery.  If the battery is discharged, it's voltage will be low and the controller will boost output to deliver the current necessary to maintain it's regulated voltage.  As the battery becomes charged, this becomes easier and easier for the alternator to accomplish so the field decreases as state of charge increases, untill the alternator is delivering just a trickle of current to maintain it's commanded voltage and float the battery at full charge.  Switch on the headlights the alternator sees the voltage drop from the applied load and boosts field and current output to maintain voltage.  The extra current this delivers powers the load while still floating the battery at full charge...  The electrical system dosn't monitor current, but it delivers varying ammounts of it to maintain a set voltage. 

A controller that senses current could vary the voltage output of the alternator to deliver a particular current. 

A programmable controller basically has several voltages it can switch between depending upon the need.  A high voltage to bulk charge a really dead battery and get the charge process started.  A slightly lower voltage for absorption charging which delivers current for the middle/majority of a charge cycle at a more efficient and less harmfull level for the battery. Once the battery approaches full charge, then it switches to a lower regulated voltage for floating the cells at full charge.  This is known as 3 stage charging.  There are other methods as well. A fancy controller may also have a very high voltage for cell equalization and mixing the electrolyte...

Do you already have inverter? Reason I ask is BOB has written a great paper on converting that ALT to 24 volts.

The advantage is fuel efficiency and course the cabling can be a lot smaller.

Just an idea.

Thnaks, that helps. 

Quote from: Mad_Labs on October 19, 2012, 07:36:56 AM
I realized I didn't quite answer your question, how do control BOTH volts and amps.

Actually, you can't control them seperately, they are ALWAYS tied together. Let's take a battery at 50% charge for an example. You start the engine and engage the alt. The controller/alt will try to raise the voltage to 14.4V. But it can't because the battery is so discharged. So the controller runs the alt as hard as it can, or if a smart controller, as hard as is safe for the alt. The alt continues to dump as much as it can and the battery voltage starts to rise. When it reaches 14.4V, the controller starts to back off the PWM on the field coil and the amps start to drop. When the amps drop low enough (how low depends on the size of the battery bank) the charge is complete. In my case with my controller, it then politely shuts the engine off. 

So, amps and volts are always inextricably tied together and adjusting the field coil PWM duty controls both at the same time.

HTH and doesn't make it more confusing. 

Jonathan

I thought about it, but I'm not sure exactly how they limit voltage and current, kinda new to power generation. I get that they are PWM the excitation current, not sure how you can control voltage and current independently.

Can you help ?

Quote from: Mad_Labs on October 18, 2012, 09:05:23 AM
If you are using a uC to control the RPM, why not just make your own field controller? Then it can behave however you like. That's what I do, mine can read volts, output amps and battery temp.. I am working on a new one that will also keep track of fuel volume consumed. I will eventually add rpm control as well, but that is more complex than field control and adds a new dimension to the field controller.

Jonathan

I have see the pololu 30amp sensor.  I'm using an arduinio clone that is made to be inbedded, The ardunio is a great device, easy to program and work with.

Quote from: scottpeterd on October 18, 2012, 01:55:34 AM

I have to say I've been very happy with the Sterling regulator. I'm using the PDAR with the 555, and I'm very satisfied with the results.  A lot cheaper than the Balmar.

As to the current sensor, have you seen the Pololu 30A sensor ( http://www.hacktronics.com/Sensors/Current-Sensor-30-Amp/flypage.tpl.html ?  It may be too small for your application, but they work very well with Arduino's and other pico-boards.

Pete

So I have been thinking. Tell me how this would work.

I have my system as described above. Except I've decided that I need a tach input so i know exactly how fast the engine is spinning. This will also keep my stepper motor in calibration.

My little genverter is humming along at 2500 rpm engine speed, when suddenly the fridge desides to kick on.

My microproccesser detects it because it's monitoring the amps drawn by the inverter.

it then

1. Tells the engine to increase RPM to the speed corresponding to the amps draw as mapped in my above post.
2. Cuts the connection to the 12v excitation source. The inverter is now drawing 100% from the 100AH 24 volt battery pack.
3. Waits until engine reaches desired rpm.
4  reconnects excitation source.

This what I fear now, is the surge caused by the compressor starting will be almost over by the time the motor gets going and the ALT starts producing again.

So the amp draw will drop. And the motor will have reve'd up for no reason, wasting fuel.

Just trying to think of a smart way to do this. i also have the ability to PWM, so i could reduce the cycle on the excitation circuit. But I fear it may confuse the Voltage reg if I do that.

Now I just think I need to build the voltage reg in with my motor speed controller.

I can figure out to program it to do what I want, just need help figuring out what is the ideal solution.

You have a good idea, I just not sure how I can incorporate it in my design. I will do more research.

Quote from: Ronmar on October 16, 2012, 07:04:54 PM
With the engine controller monitoring the current output, that might work out.  With the batteries in there to buffer the loading of the alternator, the current draw should increase before the voltage drops so far that it triggers a massive response from the voltage regulator to increase alternator output/engine load...  But without some control/delay of the voltage reg on the alternator, it still might outpace engine capacity...

Sounds like an interesting project...

Thanks for the replies. They are much appreciated.

Ronmar, I share your fear , but i believe my algorithm will be able to deal with it.

My plan is to build the complete unit without the rpm controller.

I will then set the engine speed to 2500 rpm and load the inverter until the engine rpm starts to drop. Then taking note of that load in amps, I will multiply it by 80%. I will repeat this measurement at several rpms, more than likely every 200 rpm. This will allow me to build a 2D map based on amps consumed and engine rpm. At each rpm the motor will run at a 80% load. if the load is greater, then it will instantly go to the appropriate rpm  for the amp load detected.

This way i hope to always be running at 80% throttle, no matter what rpm. ( unless the load is less at the lowest rpm) I believe this will work because the governor on the engine controls engine speed, not throttle.

This should give me the best fuel economy and also give me a 20% reserve on engine power, plus the 100ah 24 volt battery pack. also remember the engine speed controller will be asking for more engine rpm as soon as it detects an increase in amp draw.

I think it will work, but this is why I wanted to ask. This thread has already vastly improved my design and been a great help.

If doesn't work then I will try to incorporate your idea.

EDITED to clarify my idea.

Thanks. tell me if I have this right. The 3500 rpm would be the min speed?



So with a 1.43 ratio. and varying the speed with load based on amps.

               Engine speed         Alt Shaft speed

Low load    2500 rpm                       3575 rpm

Med load     3000 rpm                      4290 rpm

Max load     3600 rpm                       5148 rpm


According to my Math, if the Alt is 70% efficient and the inverter is 90%, I should be able to run a continuous 2500 watts 120 AC

So I should need about 110 amps at 28 volts from the 110-55.

So my last question is can I get 110 amps at ALT shaft 5148 rpm ?

Thanks Bob. I was hoping you would help me.

I pretty sure my pulley is 2.3, after looking at what is offered. That gives me a max ALT shaft speed of about 6500RPM. Or I could buy a larger 2. 9 pulley and give my self a little more torque at the shaft. Then my maximum shaft speed would only be about 5200 rpm.

What RPM range I'm I looking at for the 555 running 28 volts?  I'm guessing 2500 ALT shaft RPM and up.

So would think the 1.43 ratio or 1.8 ratio would be better?

Was wanting to build a Alternator powered Inverter set up.


Goal- to provide 3000 watts emergency backup power and semi portable power to run power tools etc.  This will also be a test mule for propane engine controls. Want to develop a portable power source that gets great fuel efficiency.

Parts-

Engine- 212cc Honda clone  rated at 7hp (Will convert to propane, more than likely will knock it down to 5.5 to 6 hp)

ALT. 4800 series LN, 200amp, 14 volt.

Battery- 27d deepcycle 12 volt 100AH. Battery is only in the system to to provide uninterrupted power  and to help meet the demand of a surge.

Inverter- none yet need about 3000 watts ( fridge, microwave, TV, LED lights, Laptop)

Drive will be serpentine belt. 4.2 inch utterpower pulley on motor and approx 2.5 inch pulley on the alt. I can't remember the exact size, but it maybe as small as 2.3 or so. Anyway my ratio should end up be 1.7-to 1.80, somewhere in that range.

Question i have the 14 volt 200 amp LN 4800 series J mount ( sorry can't remember exact model, it's in FL now and I'm in GA).

I was wondering If i might be better off to spend the $150 or so and get the 110-555 and another battery go with a 24 volt system, Like Bob has ingenuously and graciously described in his white paper.  The extra cost would about double my project budget. ( another battery, New alt, balmar reg)

My original plan was to use a stepper motor and microprocessor to control the engines governor speed. So that it would run slow when load was low, and then speed up when load was higher. I was also hoping that I could open the governor up quick enough to avoid the engine from stalling or straining under load.

The hold up for me going to the 110-555 and 24 volt setup is is the Balmer regulator. I think it's possible that I maybe able to mimic some of it's functions with a microprocessor , kind of build my own. Problem is if I start experimenting with $150 alternators and fry them i could have bought the balmar. Is there a cheaper regulator?  would not any external regulator work, or I'm I missing something?Also another deepcycle battery makes the unit heavier and harder to move.