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Author Topic: 24VDC generator UPDATE:  (Read 8423 times)
Len Silva
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« Reply #30 on: January 27, 2007, 04:47:12 PM »

Sure is a cute little bugger  Smiley
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« Reply #31 on: January 27, 2007, 04:59:59 PM »

If you want AGM batteries that are spill proof, etc (personally have 2-8D Lifeline AGM's and love them), stick with AGM batteries that are made in normal automotive sizes (like 8D, 4D, 31, 6v golf cart) so you can easily replace them anywhere in the country, and if need be can replace them with wet leaded batteries, since AGM's and wet batteries can be charged the same. 
 Good Luck, TomC
Points well taken. That's what I will hunt for. Thank you.
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« Reply #32 on: January 27, 2007, 06:37:10 PM »

One thing you could do to make the alternators easier to find is use two 12 volt alternators and hook em in series, then hook them to groups 12 volt batteries in series to get your 24 volts. The "center tap" between the two alternators must be hooked to the "center tap" between the 12 volt banks.   One alternator would have to be mounted totally insulated, because it's frame is going to be at 12 volt potential.
  I used this technique quite sucessfully to create a simple charging system for a hybrid electric vehicle running at 36 volts... three banks of 12 volt batteries in series, and three alternators, basically one alternator dedicated to each 12 volt bank (two of the alternators had to be mounted insulated in this app)
  The advantage is that each alternator takes care of it's own 12 volt battery bank independantly of what is being drawn from the overall system, thus you can tap 12 volts, 24 volts or in my case 36 volts from the system for various doodahs without a balancing problem.  And a 175 amp 12 volt alternator is probably going to be a lot easier to find...
Belt drive them, it's a no brainer...
Cheers
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« Reply #33 on: January 27, 2007, 06:55:41 PM »

Looks like a v-belt drive so belt drive should not be a problem as Stan mentioned.
Richard
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Homegrowndiesel
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« Reply #34 on: January 27, 2007, 07:06:21 PM »

Well Ray,

Glad to hear from others that think the same way.

I have the same engine and just bought a SW 4024, along with 2 used 280 amp 24 volt DC liquid cooled alternators.(Flea market at Arcadia)

Efficiency is easily measured in amount of $ used to generate useable energy, or more accurately described as converted to useable energy. 

A small amount of fuel can easily charge 20 amp to top off charge for barreries. With an AC unit 1800 or 3600 is required. DC can idle the engine to top off the batteries.  A certain amount of fuel is needed to detonate each revolution.


Your use sounds alot like mine also.

The proper plumbing routes the heat from that little diesel into the valved, Proheat, Engine loop. 33% efficiency turns into 66% during cool weather when some heat is needed. Add another 25% total efficiency because when you need potable hot water you can recover, I mean convert the otherwise waste heat into useable potable hot water. Of course use it to preheat your engine and add an air compressor to air up your bus for departure.


I chose 1200ah, This gives me 1 week of general lighting, water pumping, and potable hot water when used with the Proheat, or 2 days if the proheat - Webasto is run for cold weather, (not just for hot showers), or 6 hours of relaxing overnight sleeping with ac running.

I guess I am a glutton for punishment, But I Googled efficient alternator DC and found the 300 amp Alternator I tried. Worked good for 3 years so far but I have really cooked this thing at low rpms with limited airflow. (most efficient for power used according to the US grant sponsored report) Going Liquid cooled this time(easier to recapture, and control)  I agree, be gone the next day with on the road AC kicking and alternator recharging as we go to wherever we are headed.

I was looking for an inexpensive 24 volt alternator, but only found internally regulated intermittent duty cycle 25% rating at full listed capacity.. Not what I really needed.

Anyway, the key is the drive ratio on an inexpensive system. Set up properly, the rpm that the alternator makes power can be adjusted so as to not overload the engine. properly geared(belted) you are not overdriving(running to capacity) either unit.

Or a properly written logic that Responds with throttle control, and amp draw, voltage control to the field coils, will be the best for automated efficiency.

I have used rocks of various sizes to manually adjust my fuel consumption (hold open the throttle) and amp, as well as Air conditioning output.

Oh yea, you can also run it off of the oil you deep fry your turkey in. (just about the same amount of time passes for the amount of oil usedm (in generator) as turkey ate)

I should have run over to Bruces the other day when you came down. We have alot to talk about.

Catch you later

Bill




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Kristinsgrandpa
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« Reply #35 on: January 27, 2007, 07:08:42 PM »

Also, proper placement would eliminate axial strain on the engine bearings.

Ed
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« Reply #36 on: January 27, 2007, 07:15:59 PM »

As long as you are not using the AC component to drive something that is frequency sensitive, you can operate an 1800 rpm alternator from 1250 rpm to 2250 rpm without any problem. The AC frequency will vary with rpm, but the voltage regulator will maintain the output within about 5 percent.
I have a patent on a device that I invented and I used this exact technology. I was spinning a flywheel at the higher rpm and letting it coast down to the lower rpm while converting the AC to DC and operating a PWM inverter at 300 volts DC. I increased the ride thru of a flywheel motor generator set by about 1700%.
Richard



Well Ray,

Glad to hear from others that think the same way.

I have the same engine and just bought a SW 4024, along with 2 used 280 amp 24 volt DC liquid cooled alternators.(Flea market at Arcadia)

Efficiency is easily measured in amount of $ used to generate useable energy, or more accurately described as converted to useable energy. 

A small amount of fuel can easily charge 20 amp to top off charge for barreries. With an AC unit 1800 or 3600 is required. DC can idle the engine to top off the batteries.  A certain amount of fuel is needed to detonate each revolution.


Your use sounds alot like mine also.

The proper plumbing routes the heat from that little diesel into the valved, Proheat, Engine loop. 33% efficiency turns into 66% during cool weather when some heat is needed. Add another 25% total efficiency because when you need potable hot water you can recover, I mean convert the otherwise waste heat into useable potable hot water. Of course use it to preheat your engine and add an air compressor to air up your bus for departure.


I chose 1200ah, This gives me 1 week of general lighting, water pumping, and potable hot water when used with the Proheat, or 2 days if the proheat - Webasto is run for cold weather, (not just for hot showers), or 6 hours of relaxing overnight sleeping with ac running.

I guess I am a glutton for punishment, But I Googled efficient alternator DC and found the 300 amp Alternator I tried. Worked good for 3 years so far but I have really cooked this thing at low rpms with limited airflow. (most efficient for power used according to the US grant sponsored report) Going Liquid cooled this time(easier to recapture, and control)  I agree, be gone the next day with on the road AC kicking and alternator recharging as we go to wherever we are headed.

I was looking for an inexpensive 24 volt alternator, but only found internally regulated intermittent duty cycle 25% rating at full listed capacity.. Not what I really needed.

Anyway, the key is the drive ratio on an inexpensive system. Set up properly, the rpm that the alternator makes power can be adjusted so as to not overload the engine. properly geared(belted) you are not overdriving(running to capacity) either unit.

Or a properly written logic that Responds with throttle control, and amp draw, voltage control to the field coils, will be the best for automated efficiency.

I have used rocks of various sizes to manually adjust my fuel consumption (hold open the throttle) and amp, as well as Air conditioning output.

Oh yea, you can also run it off of the oil you deep fry your turkey in. (just about the same amount of time passes for the amount of oil usedm (in generator) as turkey ate)

I should have run over to Bruces the other day when you came down. We have alot to talk about.

Catch you later

Bill





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gr8njt
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« Reply #37 on: January 27, 2007, 07:25:36 PM »

One thing you could do to make the alternators easier to find is use two 12 volt alternators and hook em in series, then hook them to groups 12 volt batteries in series to get your 24 volts. The "center tap" between the two alternators must be hooked to the "center tap" between the 12 volt banks.   One alternator would have to be mounted totally insulated, because it's frame is going to be at 12 volt potential.   Cheers
Good idea of charging each 12V bank independently in the 24V configuration. And the answer to the drive is V-belt
You are absolutely right that there are more choices on the 12V alternator approach. This would also provide a good source of power for the small Kubota starter.

Now, you've got to explain to me further why the 2nd alternator needs to be mounted totally insulated. If BOTH identical alternators are negative ground and mounted as such, how will the frame of the 2nd alternator be a 12 volt potential?
Is it because of the center tap connecting the NEG and POS posts?
If both (1st & 2nd) alternator mounts are insulated, would that make it the safest approach? Thanks.
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****1982 MCI-9 Crusader-II Bus Conversion****
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« Reply #38 on: January 27, 2007, 07:39:36 PM »

Well Ray,
Glad to hear from others that think the same way.
I should have run over to Bruces the other day when you came down. We have alot to talk about.
Catch you later
Bill,
I appreciate your input and I may have to pick your brains the next time I'm down at Bruce's.
I'm already in too deep that the only way out is success.
Ray
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****1982 MCI-9 Crusader-II Bus Conversion****
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« Reply #39 on: January 27, 2007, 09:10:08 PM »

Ray, one alternator has to be isolated because it's frame is at +12 volt potential with respect to ground.
Here's a circuit:

The alternators are hooked to the batteries with dedicated wires to avoid voltage sensing problems
during charging.
Cheers
Gary
« Last Edit: January 27, 2007, 09:17:11 PM by boogiethecat » Logged

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« Reply #40 on: January 28, 2007, 05:47:59 AM »

As long as you are not using the AC component to drive something that is frequency sensitive, you can operate an 1800 rpm alternator from 1250 rpm to 2250 rpm without any problem. The AC frequency will vary with rpm, but the voltage regulator will maintain the output within about 5 percent.
I am a "Home to Campground" kind of busnut and along the way when NOT plugged in, ALL my 110V-AC use will be through a Pure Sine Wave Inverter (eg: Xantrex SW4024) fed by a FAT battery bank, so all my sensitive electronic equipments will be humming happy.
 
And like Bill (Homegrowndiesel) said in his previous post: The key to this kind of project is "proper drive ratio".
I could be wrong but I understand this as: use the right size pulley/belt combination for correct/optimum rpm to the alternator.
Example. If the Kubota runs at oprimum  2000 rpm and the alternator runs optimally at 4-6000 rpm, then I am assuming that a 1:2 or 1:3 pulley rato will extract the optimum performance/s from both equipments.

Gary, thanks for the explanation on the 12 volt potential with a dual 12V alternator set-up.
« Last Edit: January 28, 2007, 06:58:13 AM by gr8njt » Logged

****1982 MCI-9 Crusader-II Bus Conversion****
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Homegrowndiesel
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« Reply #41 on: January 28, 2007, 08:54:16 AM »

Yes Ray
You got it, The hard part is the fine tuning on sizes of pulley ratios so as not to bog the engine down.
It is easy to run it wide open and make max power.

The problem comes when you have bulk charged your batteries, and you now want to run in economy mode (just off idle) to top off the batteries. The regulator is only calling for minimal field current and not drawing alot of power from the engine. When you turn on a large AC load (microwave, Hair dryer, etc) the regulator responds and stalls the engine, as the off idle power setting of the engine cannot handle the inrush current load.

The fix is to set the pulley ratio with a compromise. Each alternator has an RPM-AMP output curve. Match up the alternator RPM where it puts out, say for this engine 20 amps, now set the engine rpm at 1000-1200.  Now when the microwave gets used the battery gets used as the buffer, the engine still purrs away charging just as you had set it to do. If you find you need to speed up the charge or handle a larger load you can increase the RPM.

Electrically, with a solenoid, or manually with a throttle lever you can now controll how many amps the alternator is capable of putting out without overloading the engine.

Oh yea 1 more thing, I would go for the serpentine belt. Half the drag of a V belt. I found with the pulley setup I have (Not optimum dual V belts and large pulleys) the drad would not allow the engine to start when cold without loosening the belts.

I really like the idea of the 4 pole direct drive alternator with a bridge rectifier, Polar Power makes my favorite. I just find it hard to drop the 8 grand.

That engine you bought has a wide RPM range, I believe up to 3200 rpm, but makes awsome torque @1800 as well as minimum fuel use.

Go for the large frame oversized alternator, you wont have to worry about a backup as it will run forever not pushed to capacity as the smaller cheaper ones.

Good luck with your choices.

Bill







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« Reply #42 on: January 28, 2007, 09:24:11 AM »

Another point-if you are running two alternators, mount them opposite of each other using to belts.  Then the tension from each alternator will cancel out each other to eliminate side thrusting.  But, I know on Kubotas made for belt drive, there outer bearing is bigger to compensate.

Powertech is making a stand by APU for trucks now.  It is a 2 cylinder Kubota or Caterpillar of 10 hp running at 2400rpm running a brushless 5000watt (derated to 5500 watt) 120v AC alternator.  Slick unit, only weighs 370lb (Including the Tundra 14,000btu A/C unit under the bed). 

My point- I just don't understand the reasoning for the systems you are designing.  You are relying exclusively on the inverter to create your primary source of AC power when away from the power pole.  You are going to have to run an alternator anyway no matter which way you go.  So for redundancy, run a 120v AC alternator since you will already have the big inverter that has the battery charging built into it.  Then you'll have two sources of AC power incase one quites.  You now have a 12v alternator on the engine and the small engine, but only one source for AC power.  With my idea, you will have an 12v alternator on the big engine (or 24v) and you could also have a small 12v alternator on the puttputt.  I just believe in redundancy.  To make the point, I have two 12v alternators on my bus (although I have the little 12v alternator disconnected on the gen since it was fighting with the inverter/charger), 120v generator and an inverter, three roof top A/C's with heat strips, two water heaters, two water pumps, two reefers, three heating systems (electric, propane, engine coolant driven).  Just my way- I KNOW you'll do it your way no matter what.  Good Luck, TomC
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« Reply #43 on: January 28, 2007, 12:36:08 PM »

My point- I just don't understand the reasoning for the systems you are designing.  You are relying exclusively on the inverter to create your primary source of AC power when away from the power pole.  You are going to have to run an alternator anyway no matter which way you go.  Good Luck, TomC

Right now, my bus is wired so that the important appliances of convenience (LCD TV, DVD player, Microwave, residential refrigerator) are powered VIA a small modified sine Trace inverter/charger feeding off from a small bank of 24v house batteries. These house batteries are wired so that they are charged by the MCI's hefty 24v alternator (at the same time as the bus batteries) when running/travelling. The two banks are separated/connected by an "Isolator"

I want to improve my present renewable energy source/system by:
1) Increase the size of the house battery bank to at least 400-600Ah separated by an "isolator" from the bus 24V battery.
........Harness the excess DC energy produced by the stout MCI's alternator and save it into a larger house bank.
........This provides a lot of free AmpHours at the end of the days travel.
2) Upgrade to a pure sine wave 4k inverter/charger and charger to be used ONLY when hooked-up at a camp-ground.
........This inverter will be more than sufficient for all my 110AC needs from a fully charged 400-600Ah "house battery bank" when I get to a Walmart parking lot or a rest area after a whole day of driving.
.........The present modified sine Trace interter/charger that I now have will be the "back-up" inverter.
3) Develop a "Fast DC Charging" system for a 400-600Ah house battery bank
 .........Used only IF and only when the house bank is depleted down to 80% so as NOT to annoy the Walmart security guard or idle-free rest areas during the night.
..........Such system should be housed in a noise reduction, vibration reduced enclosure

The peace, quiet and luxury of indulgence without the generator noise at the Walmart parking lot or any rest area is music to my ears. That's the reason for the system I am designing.

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****1982 MCI-9 Crusader-II Bus Conversion****
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« Reply #44 on: January 28, 2007, 01:01:31 PM »

My point- I just don't understand the reasoning for the systems you are designing.  You are relying exclusively on the inverter to create your primary source of AC power when away from the power pole.  You are going to have to run an alternator anyway no matter which way you go.  Good Luck, TomC

Right now, my bus is wired so that the
important appliances of convenience (LCD TV, DVD player, Microwave, residential refrigerator) are powered VIA a small modified sine Trace inverter/charger feeding off from a small bank of 24v house batteries. These house batteries are wired so that they are charged by the MCI's hefty 24v alternator (at the same time as the bus batteries) when running/travelling. The two banks are separated/connected by an "Isolator"

I want to improve my present renewable energy source/system by:
1) Increase the size of the house battery bank to at least 400-600Ah separated by an "isolator" from the bus 24V battery.
........Harness the excess DC energy produced by the stout MCI's alternator and save it into a larger house bank.
........This provides a lot of free AmpHours at the end of the days travel.
2) Upgrade to a pure sine wave 4k inverter/charger and charger to be used ONLY when hooked-up at a camp-ground.
........This inverter will be more than sufficient for all my 110AC needs from a fully charged 400-600Ah "house battery bank" when I get to a Walmart parking lot or a rest area after a whole day of driving.
.........The present modified sine Trace interter/charger that I now have will be the "back-up" inverter.
3) Develop a "Fast DC Charging" system for a 400-600Ah house battery bank
 .........Used only IF and only when
the house bank is depleted down to 80% so as NOT to annoy the Walmart security guard or idle-free rest areas during the night..
.........Such system should be housed in a noise reduction, vibration reduced enclosure

The peace, quiet and luxury of indulgence without the generator noise at the Walmart parking lot or any rest area is music to my ears. That's the reason for the system I am designing.



important appliances of convenience (LCD TV, DVD player, Microwave, residential refrigerator)

Gee. you do not run any air conditioning? In most of my 150,000 miles of travel in a conversion, the A/C was the most important appliance. Without it, all the others were of little benefit when I could not get comfortable. Travelling throughout most areas in the summer, the A/C run 24/7 for days on end.

the house bank is depleted down to 80% so as NOT to annoy the Walmart security guard or idle-free rest areas during the night..

If your batteries are only depleted 70 0r 80%, you will not be able to use a "Fast DC Charging" system without boiling your batteries. Even when the batteries are depleted to 50%, it is hard to maintain a fast charge with out boiiling them.

A well designed genset installation, properly quietened will meet all your requirements listed. I have never had a WalMart guard or idle free rest area guard question the operation of my quiet genset.
Richard

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